[From the U.S. Government Printing Office, www.gpo.gov]

                                                             FY 1992 FINAL PRODUCT Task 18
                                                                        Wave Energy Regimes








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                                                              7
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                          Design Wave Information for Chesapeake Bay
                                 and Major Tributaries in Virginia





                                                  by

                                       David R. Basco, Ph.D., P.E.
                                            and Cheol S. Shin






                                            Report No. 93-1
                                             December 1.993
              THE COASTALENGINEERING INSTITUTE

                               Departmentof Civil Engineerin,g
                                  Norfolk, Virginia 23529-0242

                                            OLD DOMINION UNIVERSITY






                         (Design Wave, Information for Chesapeake Bay
                                  and Major Tributaries in Virginia





                                                    by


                                        David R. Basco, Ph.D., P.E.
                                             and Cheol S. Shin


                                        Coastal Engineering Program
                               Civil and Environmental Engineering Department
                                          Old Dominion University
                                          Norfolk, Virginia 23529








                           This project was funded, in part, by the Virginia Department
                     %  of Environmental Quality's Coastal Resources Management
                        Program through Grant No. NA270ZO312-01 of the National
                        Oceanic and Atmospheric Administration, Office of Ocean and
                        Coastal Resource Management, under the Coastal Zone
                        Management Act of 1972 as amended.

                        This"project was also funded, in part, by the Virginia Department
                        of Conservation and Recreation, Division of Soil and Water
                        Conservation through contract No. C199-50311-93-5.




     'C%




                                              December, 1993
             6W-J11










             SUAD4ARY


                 Virginia has over 5,000 miles of Chesapeake Bay shoreline. Excessive water levels and
             accompanying wave action during storms causes shoreline erosion at many locations. The
             Shoreline Programs Section of the Department of Conservation and Recreation is responsible for
             giving advice to private property owners around the Bay as to alternatives available for shoreline
             stabilization. The economic design of each stabilization alternative (e.g. rock revetment, marsh
             vegetation, etc.) depends upon both the wave energy at the site and the value of the property,
             structures, investments, etc. to be protected.
                 Much of the property around the Bay is of relatively moderate value (farmland, single family
             dwellings, etc.). To provide for the minimum level of protection, moderate design wind speeds
             have been chosen for this study. From a historic wind data analysis for the Norfolk International
             Airport (1958-1973, 1979-1990) and the Patuxent Naval Air Station (1945-1983), a design wind
             speed of 35 mph was selected. This wind speed has about a 50 percent probability of exceedance
             in any one year and a duration of at least 6 hours.
                 Wave information is then hindcast using the simplified wind-generated, wave-growth
             formulas within the Automated Coastal Engineering System (ACES, 1992) as developed by the
             Coastal Engineering Research Center of the Corps of Engineers. These methods are essentially
             those described in the Shore Protectional. Manual (1984) but updated to include the latest field
             data for calibration. The end product is twelve wave information maps showing iso-wave height
             contours (spectral, significant wave height) and associated wave periods (peak spectral period)
             for the Chesapeake Bay and its major tributaries in Virginia. The contours depict the largest
             waves at each location that could result from all possible wind directions (fetch distances and
             averaged water depths) that reach that location.
                 The results near the entrance to the Bay do not include ocean storm and swell waves which
             propagate into this region. Further refinement of these submaps (6, 7, 8, and 9) is recommended
             through use of a two-dimensional, wave spectrum transformation model. The limited amount of
             funding available precluded the use of these wave models for this project.
                 The design wave information as presented on the submaps of this report will be used by the
             Shoreline Programs Section of the Department of Conservation and Recreation to improve the
             accuracy and consistency of their shoreline erosion control advice. They will also aid in the
             implementation of management measures governing shoreline erosion control expected to be
             imposed by Section 6217 of the Coastal Zone Act Reauthorization Amendments of 1990. These
             maps are not recommended for general design use for all coastal engineering problems around
             the Bay.


                                                             i










            ACKNOWLIEDGFIvIENTS


                The authors wish to acknowledge the help of students in CE 482/582, Introduction to Coastal
            Engineering, during the spring 1993 semester at Old Dominion University for their initial try
            at sub-map development.
             . The contract was administrated by the Old Dominion University Research Foundation under
            Project No. ODURF 534251 between I Dec. 1992 and 31 Dec. 1993. Partial funding under
            Grant No. NA270ZO312-01 was provided by the Office of Ocean and Coastal Resource
            Management within   the NOAA. This project was also funded in part by the Division of Soil and
            Water Conservation of Virginia's Department of Conservation and Recreation (DCR) through
            contract No. C199-50311-93-5. The financial support of these organizations is appreciated'.
                Mr. Carlton Lee Hill, Chief Shoreline Engineer was the project monitor for the DCR and
            assisted by Mr. Joe Baumer. The authors wish to thank these gentlemen for their help and advice
            during the project and for their diligent review of this final report. We also appreciate the
            comments and suggestions for improvement of this report as provided by Mr. Scott Hardaway
            of the Virginia Institute of Marine Science.
                The maps were drawn by Ms. Debbie Miller, Publications and Graphics Department, Old
            Dominion University. The meticulous efforts of Ms. Miller are greaffully acknowledged.










                                                 TABLE OF CONTENTS

                                                                                                          Page

            SUMMARY
            PREFACE
            TABLE OF CONTENTS
            LIST OF FIGURES                                                                                v
            LIST OF TABLES                                                                                 vii



            1.0 INTRODUCTION                                                                                I
                   1.1     Background                                                                       I
                   1 * 2   Objectives                                                                       2.
                   1.3     Work Tasks                                                                       2
                   1.4     Limitations                                                                      2

            2.0 WIND-WAVE HINDCAST MODELS                                                                   3
                   2.1     Types                                                                            3
                   2.2     ACES 1.07                                                                        3
                   2.3     Limitations                                                                      5

            3.0 WIND DATA AND ANALYSIS                                                                      6

                   3.1     Time and Spacial Variations of Wind Speeds                                       6
                           3. 1. 1 Airport Reported Wind Speeds                                             6
                           3.1.2 Spacial Variation of Wind Data                                             6
                   3.2     Norfolk International Airport Data                                               9
                           3.2.1 Wind Duration Analysis                                                     9
                           3.2.2 Exceedance Frequency Distributions                                        10
                   3.3     Patuxent Naval Air Station                                                      18
                   3.4     Relation to Major Storms (1956-1978)                                            25
                   3.5     Selection of Design Wind Speed                                                  29
                   3.6     Wind Duration                                                                   30

            4.0 BATHYMETRIC MAPS, TIDAL RANGES AND MEAN WATER DEPTHS,                                      31
                   4.1     Bathymetric Maps                                                                31
                   4.2     Tidal Ranges                                                                    31
                   4.3     Storm Surge                                                                     31.
                   4.4     Mean Water Depths                                                               35
                   4.5     Submaps for Display of Results                                                  35

            5.0 TEST CASE DEVELOPMENT - SUBMAP No.8                                                        38
                   5.1     Grid Scales and Application of ACES 1.07                                        38
                   5.2     Restricted Fetch Versus Open Water Fetch Results                                38
                   5.3     Variable Water Depth Results                                                    38
                   5.4     Composite Wave Height Maps                                                      40









                                                                                                        Page

                   5.5    Conclusions                                                                     40

            6.0 DEVELOPMENT OF WAVE INFORMATION MAPS                                                      43

                   6.1    Discussion                                                                      43
                   6.2    The Final Product                                                               43
                   6.3    Limitations                                                                     43

            7.0 CONCLUSIONS AND RECOMMENDATIONS                                                           45

                   7.1    Conclusions                                                                     45
                   7.2    Recommendations                                                                 45

            REFERENCES                                                                                    46

            APPENDIX                                                                                      48











































                                                            iv










                                                   LIST OF FIGURES

                                                                                                           Page


            Figure 1      Restricted Fetch Geometry Data.                                                    5
            Figure 2      Restricted Fetch Conventions.                                                      5
            Figure 3      The Relationship Between the Fastest Mile Wind Speed and the One                   7
                          Hour Average Wind Speed.
            Figure 4      Chesapeake Bay and Wind Observation Sites.                                         8
            Figure 5      Frictional Velocity Contour (m/sec) and Mean Wind Direction Vector                 9
                          Plot from FNOC Wind-Stress Fields and 3GWAM Model Simulations,
                          October 31, 1991 (from Jensen et al., 1993). The Rectangular Box
                          Area Represents the Spatial Extent of the Chesapeake Bay.
            Figure 6      The Histogram of the Wind Speed Versus Duration, Norfolk. (1958-1973)             11
                          (Wind Speed in 4.5 - 17.9 MPH range)
            Figure 7      The Histogram of the Wind Speed Versus Duration, Norfolk. (1958-1973)             12
                          (Wind Speed in 17.9 - 26.8 MPH Range)
            Figure 8      The Histogram of the Wind Speed Versus Duration, Norfolk. (1958-1973)             13
                          (Wind Speed in 26.8 - 35.8 MPH and Greater Range)
            Figure 9      Number of-Storm Events Versus Wind Speed Under Various Durations,                 14
                          Norfolk (1958-1973).
            Figure 10     Number of Storm Events Versus Wind Speed Under Various Durations,                 15
                          Norfolk (1979-1990).
            Figure 11     Number of Storm Events Versus Wind Speed, Norfolk (1958-1973).                    16
                             (Winds from North, East, South,- and West Directions)
            Figure 12     Number of Storm Events Versus Wind Speed, Norfolk (1979-1990).                    17
                             (Winds from North, East, South, and West Directions)
            Figure 13     Number of Storm Events Versus Wind Speed, Norfolk (1958-1973). (Winds             19
                          from North-West, North-East, South-East, and South-West Directions)
            Figure 14     Number of Storm Events Versus Wind Speed, Norfolk (1979-1990). (Winds             20
                          from North-West, North-East, South-East, and South-West Directions)
            Figure 15     Number of Storm Events Versus Wind Speed Under Various Durations,                 22
                          Patuxent (1945-1983).
            Figure 16     Number of Storm Events Versus Wind Speed, Patuxent (1945-1983).                   23
                             (Winds from North, East, South, and West Directions)
            Figure i7     Number of Storm Events Versus Wind Speed, Patuxent (1945-1983). (Winds            24
                          from North-West, North-East, South-East, and South-West Directions)
            Figure 18     The Historical Record of Fastest Mile Wind Speed, Virginia Beach                  28
                         .(1956-1978).



                                                            v









                                                                                                           Page


            Figure 19     The Historical Record of Storm Surge, Virginia Beach (1956-1978).                 32
            Figure 20     The Histogram of Storm Surge, Virginia Beach (1956-1978).                         33
            Figure 21     Definition Sketch for Water Depth.                                                34
            Figure 22     Numbered Submaps for Chesapeake Bay and Adjacent Water Bodies.                    36
            Figure 23     Grid System for Submap No.8                                                       39
            Figure 24     The Wave Information Map for Submap No. 8 Showing Iso-Wave Height                 41
                          Contours With Wave Periods in Parentheses.
            Figure 25     The Relationship Between H.,, and TP for U,,,=35 mph.,                            42

































                                                             vi










                                                   LIST OF TABLES

                                                                                                           Page


           Table 1        Variable Wind Speed Range Versus Wind, Durations Selected for This Study.         10
           Table 2        Number of Storm Events per Year for Various Wind Speeds and Direction,            21
                          (a) NIA(1958-1973) (b) NIA(1979-1990).
           Table 3        Number of Storm Events per Year for Various Wind Speeds and Direction,            25
                          Patuxent (1945-1983).
           Table 4        Summary of Major Storms at Virginia Beach, Virginia, 1956-1978 (from              26
                          Senate Document No.4, 1979).
           Table 5        The Average Mean Tidal Range for Each Submap.                                     34
           Table 6        Submap Coordinate System.                                                         37

































                                                            vii










             1.0 INTRODUCTION


             1.1    Background
                 The Shoreline Programs Section of the Department of Conservation and Recreation needs
             consistently derived design wave information when providing advice for shore protection
             alternatives for over 5,000 miles of Chesapeake Bay shoreline. To accurately describe the wave
             climate within the Chesapeake Bay, two different techniques can be employed. One is wave gaging
             and the other is wave hindcasting. Although a network of wave gages     0 might eventually provide
             a good data source, the expense involved would make it economically prohibitive. A viable
             alternative to wave gaging is to hindcast the wave climate using historical wind data.
                 A variety of techniques are presently available to estimate water wave information from wind
             data. These methods are essentially two-dimensional, numerical models requiring computer
             solution or simple charts and formulas. The simplified, wind-generated, wave growth formulas
             within the Automated Coastal Engineering System (ACES, 1992) as developed by the Coastal
             Engineering Research Center of the Corps of Engineers was utilized as the wave hindcasting
             method in this project. The shallow-water formulations of ACES are based partly upon the fetch-
             limited, deep-water forms but do not encompass duration effects..The methods described in ACES
             are essentially those in Vincent (1984), the Shore Protection Manual (SPM, 1984), and Smith
             (1991), but updated to included the latest field data for calibration of the semi-theoretical, wave
             growth formulas.
                 Long term wind data from both the Norfolk International Airport (NIA) and the Patuxent
             Naval Air Station (PNAS) were obtained and statistically analyzed for the selection of a design
             wind speed. From the various storm probability curves, directional design wind speed and wind
             duration were obtained. Also, the analyses of tide and storm surge data were carried out for
             modification of the local water depth. A map of the entire Chesapeake Bay by the Virginia Institute
             of Marine Science (VIMS, 1977) was utilized for the bathymetric calculations and the geometries
             of water bodies although the analysis was confined to Virginia waters.
                 As the final product, twelve wave information maps were developed showing both iso-wave
             height contours (spectral significant wave height, H..) at one-half foot intervals and wave periods
             (peak period, Tp) covering all the water areas of the Chesapeake Bay and its major tributaries in
             Virginia. The local wave height shown is the largest that can be developed from all fetch directions
             but restricted to wind speeds with a fifty-percent exceedance probability level in any one year.



                   Wave data is available at a few selected locations and for limited time periods as collected
             by Dr. John Boon of the Virginia Institute of Marine Science.

                                                              1









              1.2    Objectives
                  The goal of this project was to divide the Chesapeake Bay and tributary rivers into wave
              energy regimes based on the wave heights and periods predicted to be generated by a storm of
              a given exceedance probability. The results of this project is a tool to provide consistent
              shoreline management advice to the citizens and communities around the Bay. The wave energy
              maps developed in this study provide a source of accurate, scientifically determined wave
              characteristics (heights and periods) for use in the design of coastal structures for the shoreline
              of Virginia.


              1.3    Work Tasks
                  Task No.1 included two major subtasks. One developed the coastal design philosophy for
              which the wave energy maps are applicable and determined the exceedance probability for wind
              speed that matched the design philosophy. The second subtask developed the methodology to
              determine the wave energy which included: summaries of wind statistics from regional airports;
              determination of appropriate design wind speeds; determination of dominant and non-dominant
              fetch directions; calculation of average water depths for given fetches   and finally the calculation
              of wave characteristics using the wind-generated, wave hindcasting model.
                  Task No.2 developed the organizational structure, numbering system and map scales to be
              used to display the predicted wave energy regimes.
                  Task No. 3 developed one wave energy map for a limited area as a test case to validate the
              previously developed methodology.
                  Task No.4 developed wave energy maps for the Chesapeake Bay and tributary rivers in the
              Commonwealth of Virginia.


              1.4    Limitations
                  The wave information maps developed in this study do not consider nearshore wave
              transformation processes such as shoaling, refraction and wave breaking processes in surf zones.
              Therefore, the information provided can be considered as boundary conditions foruse in a
              nearshore wave transformation model. The iso-wave height contours shown on the maps are not
              those predicted from one storm with a 50 percent exceedance probability but are synthesized
              from all possible storm directions at the 50 percent level.
                  Ocean swell waves entering through the Chesapeake Bay entrance are not considered in this
              study.


                                                                2










              2.0 WIND-WAVE HINDCAST MODELS


              2.1    Types
                 Three basically different methods are available to hindcast wind-waves in coastal and bay
              waters. One approach (Hasselmann et al., 1976) requires large, main-frame computers to solve
              the two-dimensional, wave propagation and transformation equations (growth, spread, decay,
              interaction) for the directional, energy density spectrum. Parameterization of the directional
              spectrum shape reduces the computational effort so that a second approach that also uses a two-
              dimensional grid, (Holthuijsen et al., 1989) can be efficiently developed for the PC/workstation
              environment. The MIKE 21 NSW model as developed at the Danish Hydraulic Institute,
              Horsholm is an example of the latter approach. This model recently (September, 1993) has been
              installed within the Computing Laboratory of - the Civil and Environmental Engineering
              Department at Old Dominion University.
                  The third approach further reduces the spectral shapes into a common family that together
              with field data have been converted into formulas and nomographs for wind-wave hindcasting
              purposes. Wave characteristics (height and period) are determined from three wind parameters
              (speed, duration and fetch distance) in deep water and have been modified to include depth-
              limiting effects (i.e., dissipation) for shallow water. These formulas are essentially one-
              dimensional estimates for wave characteristics along a dominant fetch direction and directional
              spreading of wave energy is implicitly included in the formulations. The wave-hindcast formulas
              as specified in the SPM (1984) and as incorporated and refined within the ACES (Version 1.07)
              software package are employed for this project. The water waves are characterized by the
              spectral, significant wave height, H.. and the peak spectral period, TP.


              2.2    ACES 1.07
                  The methodologies represented in the latest formulation (Version 1.07) of ACES provide
              quick and simple estimates for wave growth over open-water and restricted fetches in deep and
              shallow water. Also, improved methods (over those given in the SPM, 1984) are included for
              adjusting the observed winds to those required by wave growth formulas. Wind-waves grow as
              a result of a flux of momentum and energy from the air above the waves into the wave field.
              The frictional effects due to the presence of the water and the land surface distort the wind field
              thus, wind speed and direction become dependent upon elevation above the mean surface,
              roughness of the surface, air-sea temperature difference, and horizontal temperature gradients.


                                                              3








              For this project, the elevations have been corrected to the standard, 10 ni reference level and
              all temperature corrections are taken at the default values as specified by ACES (1.07).
                  All wave conditions generated assume constant water depths over the storm duration,
              therefore, changes in the water elevation caused by -the tides during each storm event are
              neglected. The wave growth formulations which follow are separated into four categories. Both
              deep- and shallow-water forms for both simple open water fetches and complex, limiting
              geometries designated as restricted fetch conditions are considered.
                  In open water, wave generation is limited by the dimensions of the meteorological event
              under investigation and fetch widths are of the same order of magnitude as the fetch length. The
              formulas for wave growth under open water fetch conditions do not include fetch width or shape
              effects. The more limiting or complex geometries of water bodies such as lakes, rivers, bays,
              and reservoirs have a significant impact on wind-wave generation.
                . The restricted fetch methodology applies the concept of wave development in off-wind
              directions and considers the shape of the basin. Radial fetch lengths and angles measured from
              the point of interest are used to describe the geometry of the basin. Figure 1 illustrates the
              relevant geometric data required for the restricted fetch approach. The conventions used for
              specifying wind direction and fetch geometry are illustrated in Figure 2.






                                                                     North
                                 _A*I  Point of Interest
                        19-


                                                                                 a
                                                         Point of !nterest
                                      Radial F,@tcries

                                                                                                        Fe tc h,
              Wind
                                                                          L
                                                North
                                                                                                        Fetch2
                                                                                             Fetch
                                                               W'nd


                                                                   Waves                Fetc h.




              Figure 1 Restricted Fetch Geometry Data.              Figure 2 Restricted Fetch Conventions
                                      1P








                                                            4









            The approach wind direction, ot as well as the first radial fetch angle, 01 and the radial fetch
            increment, A@ are specified in a clockwise direction from north at the point of interest where,
            wave growth prediction is required.
                Hindcasting procedures are as follows for the restricted fetch method.
                    1. select a point of interest
                    2.  define the longest fetch length and direction from all possible direction
                    3.  input the wind direction from the longest fetch direction
                    4.  compute mean water depth along the longestfetch by the weighted-average method
                    5.  measure radialfetch lengths and angles to describe the geometry of the basin
                    6.  input all data into ACES.


            2.3    Liniftations
                The ma or assumptions and limitations regarding the use of the simplified ACES (1.07)
                        i
            model include;
                       energy./rom the presence of other existing wave trains (e.g. ocean swell)
                        is neglected,
                       relatively short fetch geometry (F :5 75 miles),

                       relatively constant wind speed and direction,

                       wind prescribed at the 10 meter elevation,

                       neutral stability condition,
                       fixed value of drag coefficient,

                       nearshore wave transformations are not considered,
                       depth-induced wave breaking and surf zone process are not defined.















                                                           5










             3.0 WIND DATA AND ANALYSIS



             3.1    Thne and Spacial Variation of Wind Speeds
             3.1.1 Airport Reported Wind Speeds
                 Generally, the airport reported wind speeds are the fastest mile wind speed. The fastest mile
             wind speed, because of its short duration, should not be used to determine the wind speed for
             wave generation. Therefore, the fastest mile wind speeds must be converted to the one-hour
             average wind speed using methodology outlined in the Shore Protection Manual (SPM, 1984).
             Figure 3 shows the relationship between the fastest mile wind speed and the one-hour average.
             wind speed with a regression line and an equation as determined by the SPM                   1984)
             methodology-


             3.1.2 Spacial Variation of Wind Data
                 Figure 4 shows the location of two, long term meteorological sites: Norfolk International
             Airport (NIA) Norfolk, Virginia for representation of the lower Chesapeake Bay wind field and
             the Patuxent Naval Air Station (PNAS) Patuxent, Maryland for the upper Chesapeake Bay wind
             field. PNAS is located on the western shore of the Bay at the mouth of the Patuxent River. The
             Norfolk Airport is close to the Chesapeake Bay entrance as shown in Figure 4. Also, a very
             limited amount of wind data was obtained from Wallops Island, Virginia but this site was not
             considered as a wind source due to insufficient length of data.
                 ACES assumes a constant wind speed and duration over the water body. Because of the size
             and length of the Chesapeake Bay, this assumption may be of concern. The rectangular box area
             in Figure 5 represents the boundaries of the Chesapeake Bay and its major tributaries as
             superimposed over the wind velocity vectors for the October 31, 1991 (Halloween Northeaster)
             storm event as modelled for the'Mid-Atlantic Ocean (from Jensen et aL, 1993) The figure shows
             the frictional velocity contour (m/sec) and mean wind direction vector plot from the Fleet
             Numerical Oceanography Center (FNOC) wind stress fields as employed in the directional,
             discrete wave spectral model (3GWAM). From this example it can be seen that both the
             magnitudes (arrow length) and directions of the wind field remainfairly uniform within length
             scales of the Chesapeake Bay but, of course, change in magnitude and direction over length
             scales for the Atlantic Ocean. 'flierefore, the wind-wave hindcast results from ACES 1.07 for
             Chesapeake Bay should give reasonable results for storm events.




                                                             6










                     60-


                                      Regression Line,
                                      Y = 0.7576*X + 2.9655
                                      Y is one-hour average wind speed
                                      X is-fastest mile wind speed.

                  (U



                  rn
                     40-






                  bJD    -
                     30-

                  (U
                  I>
                  Cd



                     20-
                  0





                   0
                     10-.







                       0-
                         0           10          20           30          40           50           60          70           80
                                                      Fastest mile         wind speed, mph

                         Figure 3 The Relationship Between the Fastest Mile Wind Speed and the One Hour Average Wind Speed.








                                 77000'                                     76000'                               75000'










             390w,          Washington, D.C.


                                                              0











                                 Patuxent Naval Air Statio


                                                                  0



             38'00'                                S,                                                       Maryland

                                                                                                        Virginia
                                                                    co




                                                                    co




                                                                    Ib
                                        .j 0-.





                                             :J


             37000'

                                                        V..
                                                                        Norfolk Inte
                                                                                    mational Airport


          Figure 4   Chesapeake Bay and Wind Observation Sites.

                                                                 8








                      43
                                                                                       7 7




                                                                          ........ . .
                      42




                      41




                      40



                      39



                      38-



                      37
                                         Cq                        7-1

                      36




                      35-
                         -76      -75       -74      -@3       -@2       -71      -70      -69
                                                       Longitude

            Fi gure 5 Frictional Velocity Contour and Mean Wind. Direction Vector Plot from FNOC Wind
                     Stress Fields and 3GWAM Model Simulations, Oct. 31, 1991 (Jensen et al., 1993).
                    The Rectangular Box Area Represents the Spatial Extent of the Chesapeake Bay.



            3.2    Norfolk International Airport Data
            3.2.1 Wind Duration Analysis
                A total of thirty-two years of wind data observed at the NIA was obtained from the National
            Climate Data Center (NCDC) with fifteen years of summarized data from October 15, 1958
            through August 23, 1973; five years of data from August 24, 1973 through December 31, 1978,
            and twelve years of hourly digitized wind observations from January 1, 1979 through December
            31, 1990. The digitized wind data from 1979 through 1990 were analyzed for the directional
            storm probability curves.


                                                           9









                Figures 6, 7, and 8 show duration histograms for various ranges of wind speed during 1958
            through 1973. It is apparent from these figures that the sustained wind duration diminishes with
            increased wind speeds. For this study, three possible lengths of storm events considered were
            6 hour, 12 hour, and the variable duration model as given in Table 1.


            Table 1 Variable Wind Speed Range Versus Wind Durations Selected for This Study

                    Wind Speed Range (mph)                             Duration (hour)

                             < 8.9                                        24

                         9.0- 17.9                                         15

                        18.0-26.9                                          9

                        27.0-35.9                                          6

                             > 36.0                                        3


            3.2.2 Exceedance Frequency Distributions
                The number of storm events per year was calculated from the analyses of the probability of
            exceedance. Figures 9 and 10 show storm probability curves for these three storm durations
            during 1958-1973 (15 years) and 1979-1990 (12 years), respectively. From Figures 9 and 10 it
            was concluded that

                        variable storm duration gives more representative results,
                        both Figures 9 and 10 show consistent trends over a twenty-seven year span,
                        the 100 percent exceedance probability storm wind speed equals 33 mph, and
                        the 50 percent exceedance probability storm wind speed equals 36 mph.
                 Figures 11 and 12 show storm probability curves for the four main compass directions
            (North, East, South, and West) for both 1958-1973 and 1979-1990 periods, respectively.
            Directional wind speeds were obtained from the directional probability analyses. From these
            analyses, it was concluded that
                       winds from the North and West dominate,

                       both time periods shows similar trends,
                       the 100 percent probability storm wind speed equals 2 7 mph for the North,direction,

                        and

                       the 50 percent probability storm -wind speed equals 31 mph for the North direction.


                                                            10





                      5000-

                                                                                              Wind Speed Range
                      4500-
                                                                                                      4.5 - 8.9 MPH
                                                                                            ------    9.8 - 17.9 MPH
                      4000   - ----------------



                    rn 3500-


                    (U
                    >
                      3000-


                    0
                      2500-



                      2000-
                    z

                      1500-



                      1000-                         -----------------

                                                                         --------------------------------


                         500-



                                                                                                                   ----------------
                            0-
                              0         3          6         9         12         15        18         21         24        27         30
                                                             Consecutive Hour, hr

                              Figure 6 The Histogram of the Wind Speed Versus Duration, Norfolk (1958-1973).
                                                 (Wind Speed in 4.5 - 17.9 MPH Range)






                           600-

                                                                                                              Wind Speed Range
                           500-                                                                                         17.9           26.8 MPH




                           400-




                       4-4
                       0
                           300-



                       z   200-.



                           100-




                               0                                        1 r-r' II I-r I I I I I I I I I I I I   I -T-r-r-r7-T
                                  0           3            6           9           12           15          18           21           24          27           30
                                                                       Consecutive flour, hr

                                  Figure 7 The Histogram of the Wind Speed Versus Duration, Norfolk (1958-1973).
                                                           (Wind Speed in 17.9 - 26.8 MPH Range)






                       50-

                           -                                                                Wind     Speed Range.
                       45-
                           -                                                                       26.8 - 35.8 MPH
                           -                                                             ------              > 35.8 MPH
                       40-



                    M  35-



                       30-

                    4-4
                    0
                    ;-4 25-
                    (U

                       20-
                    z





                       10-



                        5  -----------------



                        0
                           0          3         6          9         12         15        18         21         24        27         30
                                                          Consecutive flour, hr

                           Figure 8 The Histogram of the Wind Speed Versus Duration, Norfolk (1958-1973).
                                             (Wind Speed in. 26.8 - 35.8 MPH and Greater Range)





                                 40                                                                                                         1 1 till

                                                                                                                                    Vati4bld           Puratioij
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                                                                                                                             i.?    Coh9flaht iDuralioh                       12h
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                                                                                        I              I   Ifill                            I I till                              I  I I    I
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                                                                       Ill"l,                  I   I   I   Itill             I           I I I till                I      I                 I
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                                 30                                                                                          1      1    1  1 1   till             I      I   I I    I fit

                                                                                                            I  :It           I           I  I I   till             I      I   I   I  I 1 11
                                                                                                                I I          I           I  1 .1  till             I      I   I   I  I III
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                                                                                        I                         I          I      I    1  1.1   till             I      I   I   I  I III





                                               --L--J--L-L-J-LLLL              - - - - -L--J--L-L-J-L                                     -L -J-L L LL   - - - - - L--J--L-L.J-LLL
                                                   1      1   1   1  1 1 111            1      1   1   1   11                                  1 till              I

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                                                                         I I I          I      I   I   I   Ifill
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                                                   L              L J -L- L L L -----   L     J    L   L J -L L L. L -----   L--J--L          -J-L-LLL--                     -L-     -LLL
                                 10   -------      :              :  : 11 :::                  11  11  :   :11  :111,        11     11   11 :  :  11 11111,                  V@        16: :
                                                   I      I   I   I  I I [it            I      I   I   I   II  III           I      I    I  I  I  I III                       1@,    it  it
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                                                                                                                             i      i    i  i  F-f+ 1                     i   i 1 1    1-M
                                     0.1                                    1                                   10                                   100                                 1000
                                                                                   Number              of     Storms           per       Year
                                                                                                                                                                 @4

                                                                                                                                                       L
                                                                                                                                                                   L     I
                                                                                                                                                                   4
                                                                                                                                                                   I ,
                                                                                                                                                                   L
                                                                                                                                            @111111 fit








                                       Figure 9 Number of Storm Events Versus Wind Speed under Various Durations, Norfolk. (1958-1973)







                   40-

                                                                    o o o    CoMthhtl Dura@tioh@6
                                                                             Cohgtlaht', Dura;tioh    1211


                                                     -'--J--L-L-J-LLLL ----- L---J--L-L-J-LLLL ----- L--.J--L-L-i.-LLL
                   30---









                       ------- L--J--L-LJ-LLLL -----  L--J--L-LJ-LLLL ----- --J   LJ-LLLL - - - - -L---J--L-LJ-LLL
                   20

                ca


                                                                                    r

                                                                                  I I  I -t'j Nq   I  I I I III



                              I  f  I I II III


                              L--J--L-L-J-LLLL -----  L---J--L-L-J-LLLL -----
                   10  -------









                    0-

                                                                   10                  100                   1000
                                                Number      of Storms     per   Year
                                                             14  1
                                                              Z




















                      Figure 10 Number of Storm Events Versus Wind Speed under Various Durations, Norfolk. (1979-1990)







                         40


                                                                                                                     North
                              -- - - - -    I           +                                     -1- -1      JAtj_"+ jE"t - -
                                                                                                I     i   113--9 w3-9 ISPuth         I       I
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                                                                                                                           A   0



                           0
                             0.1                                          1                                           10
                                                                   Number         of    Storms        per    Year
                              Figure I I Number of Storm Events Versus Wind Speed,      Norfolk (1958-1973).
                                              (North, East, South, and West Directions)








                             50-


                                                      I I I   fill           I    I   I I 1 1111             1     1   1          1 kNorth         I   I  I I  I  I
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                                                                                                                       C3 I



                                                                                                              IN,                     IN
                                                                                                                   L,' I I 1 1 14  1                           11 1
                             10              L -I- L LU U L                  L -I- L LU U L                  L -I- L-,,Ll     I U L--                  L LI-J U
                                             I    I   I   I I I III          I    I   I   I  II III          I     I   I  1 -1'41 if     3"11 d-@@*L I       I III
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                                             1                                                                                                  0
                                             I    I   I   I I fill           I    I   I   I  II III          I     I   I  I I  fill                I I'l     I III
                                             I    I   I   I I fill           I    I   I   I  II III          I     I   I  I I  fill           I "-I    I I   I III
                                                              Jill
                                0            i    I   i   i i 1111
                                 0.01                             0.1                                                             10                              100
                                                                            Number           of Storms           per Year
                                  Figure 12 Number of Storm Events Versus Wind Speed, Norfolk (1979-1990).
                                                      (North, East, South, and West Directions)








                Figures 13 and 14 show storm probability curves for four sub-compass directions" (North-
            West, North-East, South-East, and South-West) for both 1958 - 1973 and 1979 - 1990 periods,
            respectively. From these analyses, it was concluded that :
                       winds from the North-East and North-West dominate,
                       the 100 percent probability storm wind speed equals 28 mph for the North-East
                       direction, and
                       the 50 percent probability storm wind speed'equals 31 mph for the North -East

                       direction.
                Table 2 shows the number of storm events per year with directional wind speed for both the
            1958-1973 and 1979-1990 analysis periods.


            3.3    Patuxent Naval Air Station
                A total of 39 years of pre-analyzed wind data were obtained from the Chesapeake Bay
            Shoreline Erosion Study Report (1990). It was ass   umed that three possible lengths of storm
            events were 6 hour, 12 hour, and the variable storm duration from Table 1.
                Figure 15 presents the storm probability curves for three durations during 1945 - 1983.
            From this analysis, it was concluded that :
                       variable duration is more realistic,

                       the 100 percent probability storm wind speed equals 36 mph, and
                       the 50 percent probability storm wind speed equals 40 mph.
                Figure 16 displays storm probability curves for four main compass directions (North, East,
            South, and West) for the 1945 - 1983 period. From this analysis, it was concluded that
                    ï¿½ winds from the North and East dominate,

                    ï¿½ the 100 percent probability storm wind speed equals 22 mph for the North direction,

                       and
                    ï¿½ the 50 percent probability storm wind speed equals 24 mph for the North direction.
                Figure 17 presents storm probability curves for the four sub-compass directions (North-
            West, North-East, South-East, and South-West) for the 1945-1983 period. From this analysis,
            it was concluded that



                   For this report, we have employed an alternate spelling of northwest, northeast, etc. to
            emphasize that we are considering winds within the entire quadrant from the North-West, North-
            East, etc., directions.

                                                          18







                           40-


                                                                                                                    il*** North-Ifeqtl                     I  I I
                                                                                                         I   I  I  II Ai         North-INaElt I            I  I I
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                       rd                                                                                                                                       I
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                             0-
                              .0.1                                         1                                         10                                         100
                                                                          Number          of     Storms         per Year
                                                                    T























                                 Figure 13 Number of Storm Events Versus Wind Speed, Norfolk (1958-1973).
                                             (North-West, North-East, South-East, and South-West Directions)






                                50-


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                                10                 L -I- L LLA U L                     L -I- L LU U L                       L -I- L L 1@1 @U L                               L LIJ U




                                                   I     I   I   I  I I III            I      I   I   I I  I  III           I      I    I  I  I  I  III           I      I I I rl        it
                                   0                                                     ____T    I __F_T_T_I I                                                   I      I
                                    0.01                                  0.1                                                                        10                                    100
                                                                                      Number             of Storms                per      Year
                                                                                                                                                                       C,    I   I
                                                                                                                                                                                    I
                                                                                                                                                                                 I  I
                                                                                                                                                                  I          IL I-


                                      Figure 14      Number of Storm Events Versus Wind Speed, Norfolk (1979-1990).
                                                   .(North-West, North-East, South-East, and South-West Directions)











             Table 2 Number of Storm Events per Year for Various Wind Speeds and Directions for the
                       Norfolk International Aizport Data Set.


             a) NIA (1958 - 1973)
                (Data in this table has been truncated during analysis by the NCDC.)


                 MPH North             East       South       West      N-W        N-E        S-E        S-W

                 4.47       32.5       12.2       33.9        15.48     37.2       67.8       33.2       79.64
                 8.95    1  24.7        5.2       15.9        9.95      25.8       45.0       12.5    1  50.88

                13.42       23.6        1.8        8.3        8.26      23.6       32.4        5.3       38.93

                1790         6.5                   1.2        1.77       5.9        7.7                   9.44
                2 .37    1   2.0                                                    2.0                   1.97

                26.84





             b) NIA (1979 - 1990)
                (Data in this table was analyzed as part of this study and was not truncated.)


                 MPH        North      East       South       West       N-W        N-E        S-E        S-W

                   4.47     46.13      15.64      48.60       23.71     33.44      59.31      28.13      63.84

                   8.95     34.51       6.82      26.50       14.74     21.88      39.38      12.09      40.16

                 13.42      29.84       2.92      16.30       10.60     18.62      29.26       5.48      27.31

                 17.90       9.72       0.54       4.40       3.36       6.24       9.19       0.80       6.90

                 22.371      3.70       0.12       1.60       1.32       2.12       3.54       0.23       1.85
                 26.84       1.32       0.07       0.40       0.47       0.50       1.46       0.07       0.53

                 31.32       0.54       0.06       0.09       .0.19      0.14       0.52       0.03       0.20

                 35.79       0.12.      0.02                                        0.18
              1  40.27   1         1           1                                    0.10



                                                              21





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                              0
                               0.01                    0.1                         1                     10                      100                     1000
                                                                     Number          of    SLorms        per     Year
                                Figure 15 Number of Storm Events Versus Wind Speed under Various Durations, Patuxent. (1945-1983)








                            40


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                                         0.01                             0.1                                 1                               10
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                                                                         Number of Storms per Year
                                 Figure 16 Number of Storm Events Versus Wind Speed, Patuxent (1945-1983).
                                                  (North, East, South, and West Directions)








                        60


                                                                                                     It It  North-'qe:gt I I
                                                                             I1 11       1   1    1 A" "I   Nortb-FAasit 1 1      1  1
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                       20----                                                                     L LIJ            *L
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                                    L -I- L LU U L            L -I- L LU U L             L -I- L LI    I LJ L           I- ci@   1 A LJ



                         0  1                                                                i    i    H 11         if        i  Ifill
                         0.01                        0.1                         1                         10                        100
                                                              Number       of Storms          per    Year
                           Figure 17 Number of Storm Events Versus Wind Speed, Patuxent (1945-1983).
                                     (North-West, North-East, South-East, and South-West Directions)









                    ï¿½ winds ftom the North-West and South-East dominate at this location,
                    ï¿½the 100 percent probability storm wind speed equals 34 mph for the North-West
                     direction, and
                    ï¿½the 50 percent probability storm wind speed equals 36 mph for the North-West

                     direction
                Generally, the wind speeds at the PNAS are slightly stronger than at the NIA because the
            wind blows along the Patuxent River from the mountain ridge to the lower PNAS which is
            located at the mouth of the Patuxent River. Another possible reason is PNAS is located at a
            higher latitude. Table 3 summarizes the results of the number of storm events per year for
            various directional wind speeds at the PNAS.


            Table 3 Number of Storm Events per Year for Various Wind Speeds and Direction,
                     Patuxent (1945 - 1983).


                MPH       North    East      South      West      N-W        N-E       S-E        S-W

                10         11.20     3.60       9.60       7.64      55.10      21.80     27.40      39.39
                15         -5.30     1.02       2.60       3.27      42.40     9.70       10.40      15.45
                20         1.60      0.25       0.50       0.96      19.10     2.60       2.30       2.97

                25         0.60      0.12       0.06       0.26      9.40      0.70       0.33       0.51

                30         0.15      0.03       0.01       0.05      2.60      0.20       0.24       0.06
                35         0.01                            0.01      0.80      0.08       0.16       -0.03

                40                                                   0.20                 0.08       0.03

                45                                                   0.10
            L--iO-



            3.4     Relation to Major Storms (1956-1978)
               . In the 1970's, three study reports documented major storms along the Virginia coast.
            Ho et al., 1976 reported on storm tidal frequencies and this information was combined with
            wind speeds and durations by Pore and Richardson (1977) as Chapter 15 in a special report by
            the Virginia Institute of Marine Science (VIMS) as compiled and edited by Goldsmith et al.,
            1977. These study reports became the basis for a 1979 report by the Coastal Erosion Abatement


                                                           25








           Table 4 Summary of Major Storms at Virginia Beach, Virginia 1956 - 1978. (from Senate
                    Document No.4, 1979)

                Storm          Date        Storm Surge     Wind Speed    Wind Speed      Direction
             Description          -           (feet)        (knot)         (mph)
                             01/11/1956       3.4             33             38            N-E
                             04/11/1956       4.3             62             71             N
                             11/03/1956'      2.0             29             33            N-E
                             02/28/1957       2.4             33             38            N-E
                             03/08/1957       2.2             27             31            N-E
                             11/01/1957       2.7             28             32            N-E
                             01/25/1958       2.3             44             50             E
                             02/01/1958       .2.2            30             34             w
                             03/19/1958       .2.2            21             24            N-E
                             03/27/1958       2.6             20             23             N
                             12/11/1958       2.1             27             31            N-E
                             12/29/1958       2.3             38             43             E
                             04/12/1959       2.5             45             51            N-E
                             12/19/1959       2.1             29             33             N
                             01/31/1960       3.0             42             48            N-E
                             02/13/1960       2.3             49             56            N-E
                             03/03/1960       2.4             52             59             E
                             12/12/1960       2.0             40             46             w
                             01/16/1961       2.0             13             15             w
                             02/08/1961       2.4             27             31            N-E
                             03/22/1961       2.2             33             38             E
                             11/28/1961       2.0             23             26            N-W
                             01/28/1962       2.2             37             42            N-E
              Ash Wed.       03/07/1962       5.6             41             47            N-E
                             03/22/1962       2.4             20             23             N
                             11/03/1962       2.5             33             38             N
                             11/26/1962       3.3             41             47             N
                             02/08/1963       2.3             30             34            N-E
                             11/06/1963       2.4             38             43             E
                             01/04/1964       2.0             28             32             w
                             01/12/1964       2.6             42             48             E
                             02/12/1964       2.0             32             36             E
                Cleo         09/01/1964       1.0             42             48            ESE
                Dora         09/13/1964       u               61             70            'N-E
                Gladys       09/23/1964       2.3             44             50             N
                Isabell      10/16/1964       2.6             50             57            N-E
                             01/16/1965       3.9             35             40            N-E
                             01/22/1965       3.0             36             41             E@I


                                                       26










                                                  Table 4    Continued

                                01/29/1966        3.6              37               42              E
                  Alma          06/14/1966        2.3              31               .35            N-E
                                12/24/1966        1.0              40               46              N
                                02/07/1967        2.6              33,              38             N-E
                                12/12/1967        2.0              30               34              E
                                12/29/1967        2.0              31               35              W
                  Doria         09/16/1967        3.4              55               63              N
                                01/14/1968        2.3              33               38              E
                                02/08/1968        2.6              30               34             N-E
                  Gladys        10/20/1968        1.3              46               53             N-E
                                11/10/1968        4.3              34               39              N
                                11/12/1968        2.6              47               54             N-E
                                03/02/1969        5.9              40               46              N
                                11/02/1969        2.6              36               41             N-E
                                11/10/1970        2.6              22               25             S-E
                                12/16/1970        2.0              31               35              E
                                03/27/1971        2.8              45               51             N-E
                                04/06/1971        4.0              44               50             N-E
                                .10/19/1972        -               34               39              N
                                02/11/1973        3.5              44               50              N
                                03/21/1973        3.1              28               32              N
                                03/02/1975        2.2              22               25             SSE
                                10/14/1977        2.6              29               33             N-E

                                                                                                    T '0
                                10/30/1977        2.3              24               27             N-jr,
                                04/28/1978        4.6              39               45             N-E

             Commission to the Governor and General Assembly of Virginia called Senate Document No.4
             (1979). Table 4 is the summary from Senate Document No.4, 1979 for the 23 year period 1956-,
             1978 that included both tropical storms (named hurricanes) and extratropical storm (northeaster)
             events. Unfortunately, the criteria to define a "storm" event (i.e. storm surge level or threshold
             wind speed) were not specified.
                 The location and elevation of the wind gauge are unknown (Richardson, 1993, personal
             communication) and it was learned that the reported wind speeds are the fastest mile wind speed.
             Because of its short duration, the fastest mile wind speed must first be converted to a one hour
             average wind speed using the SPM (1984) methodology as summarized in Figure 3.
                 The wind speeds tabulated for the sixty-two major storms listed in Table 4 were converted
             to one hour averages and plotted in Figure 18. The mean was 33.4 mph with a standard
             deviation of ï¿½ 8.3 mph at the 95 percent confidence level. As seen in Figure 9 for the Norfolk
             Airport over the same time period, this average wind speed is at the 100 percent probability


                                                            27






                      70.0


                                                                                  MEAN = 33.4 mph
                                                                                  STANDARD DEVIATION               8.34    mph
                      60.0







                                  - - - - - - - - - - - - --




                                                                                                                                     ><

                      40.0                                                                                                           z


                  P-4                                                                                             MEAN'              z
                                                                                                                                     LLI
           00         30.0                                                                                                           LL-
                                                                                                                                     z





                      20.0


                                  - - - - - - - - - - - - - - - - - - - - - - - - -



                      10.0



                        0.0                                  r-T                                                  T-
                           1955                 1960                 1965                 1970                  1975                 1980
                                                                              YEAR


                             Figure 18 The Historical Record of Fastest Mile Wind Speeds, Virginia Beach (1956-1978).









             level (one storm per year) in any one year. A similar result is evident in Figure 10 for the 1979-
             1990 analysis period. Thus the averaged, one hour wind speed for 62 major storms over a 23
             year period has a 100 percent chance of occurrence each year and is about 33 mph.


             3.5    Selection of Design Wind Speed
                 The economic design of shoreline stabilization alternatives (e.g. a rock revetment, vegetated
             marshes) depends upon (1) the wave energy at the site (2) the water level at the site and (3)
             the value of the property, structure, investments, etc. to be protected. The coastal engineering
             design philosophy adopted for this study is simply that the benefits resulting from storm damage
             protection are roughly equivalent to the costs for shore protection in any one year. And, since
             much of the property value for the 5,000 mile shoreline of Virginia around the Bay is of
             relatively moderate value, this translates into a relatively moderate wave energy level to provide
             for the minimum level of protection. Site specific locations where shoreline erosion threatens
             high value property (marinas, roads, major buildings, infrastructures, etc.) are not considered
             as applicable for the wave information reported herein. Special oceanographic engineering
             analyses of the design wave conditions are required for these cases.
                 From the historic wind data analyses for both the Norfolk and Patuxent locations, the 100
             and 50 percent chance probability storm winds speeds are about 30 and 35 mph, respectively for
             winds of all directions. However, the relatively narrow tributary estuaries are generally aligned
             along the South-East (or North-West) direction for longest fetch considerations. At the same 100
             and 50 percent probability levels, wind speeds   are about 20 and 25 mph, respectively from the
             South-East direction.
                 These wind speeds were tested for Submap No.8 (see Section 4) to determine the relative
             difference in hindcast wave heights for the 30 and 35 mph conditions. It was found that for
             northern winds aligned along the entire Bay, the additional 5 mph wind speed increased the wave
             height by one foot or less. Other directions produce less than one-half foot increase in wave
             heights for the extra 5 mph wind speed.
                 All the above mentioned results were presented and discussed at a meeting with the
             Shoreline Programs Office. At this meeting (8 July, 1993) the design wind speed of 35 mph was
             selected for use to hindcast wave information for the Bay and all the major tributaries. This wind
             speed has about a 50 percent probability of exceedance in any one year or a 2 year recurrence
             interval. This design wind speed is compatible with the average wind speed occurring during 62
             major storms over a 23 year period.


                                                             29








                 The 35 mph design wind speed is. used for winds blowing from all directions along all
             possible fetches in the Bay and major tributaries. However, a 25 mph design wind speed has
             been employed for the South-East direction along the axis of the relatively narrow major
             tributaries when this direction is being used in the hindcast procedure.


             3.6     Wind Duration
                 The shallow-water, wave growth formulations of ACES are based partly upon the fetch-
             limited deepwater forms and do not encompass duration effects. Consequently, it is assumed that
             all waves are fetch-limited in size and that wind durations are sufficient so as to not to limit

             wave growth.
                 Histograms of number of events versus consecutive hour durations are presented in Figures
             6, 7, and 8 for various wind speeds and were used to derive Table 1 as previously discussed.
             A six hour duration storm is consistent with wind speeds in the 35 mph range. About 40, six
             hour storms with speeds in the 27-36 mph range occurred over the 16 year period (1958-1973).
             Hence it is conservative to assume that six hour duration events can occur with a 50 percent
             probability each year.
                 Longer fetch distances require longer duration storm events to reach fully arisen seas. The
             wave growth formulations in ACES are said to give reasonable results for fetch distances under
             75 miles. Although ACES shallow-water formulations do not encompass duration effects, the
             shallow-water forcasting curves in SPM were utilized to estimate the minimum durations. From
             these results, it was concluded that a six hour duration is sufficient for fully arisen sea conditions
             for fetches less than 75 miles'. Therefore for some areas of the lower Chesapeake Bay where
             fetch distances exceed 100 miles, longer than 6 hour duration events are probably needed. Or
             conversely, a 6 hour duration means that the waves are possibly duration-limited in this region.
             As seen in Figure 8, consecutive hour winds blowing longer than 6 hours are rare. Hence, the
             assumption that all waves are fetch-limited for this study simply means that the wave heights
             reported for the lower Bay are conservative, namely larger in size than if duration-limited
             growth formulas are applied.









                                                               30









             4.0 BATHYMEETRIC MAPS, TIDAL RANGES, AND MEAN WATER DEPTHS


             4.1     Bathymetric AUps
                 The bathymetric chart    of the Chesapeake Bay as developed by the Virginia Institute of
             Marine Science (VIMS, 1977) was used for the bathymetric determination. The scale of this map
             is I  : 224,700. Bathymetry of this chart is based on depths from National Ocean Survey
             Sounding Sheets and contoured to Mean Low Water (MLW) datum. Land forms are also adopted
             from National Ocean Survey Charts. It was assumed that the land forms and the depth contours
             have not changed appreciably since 1977.


             4.2     Tidal Ranges
                 An estimation of the Mean Tidal Range (MTR) is essential for the calculation of a local
             mean water depth because the bathymetric chart is contoured to Mean Low Water QvILW)
             datum. Therefore, one half of the MTR is added to the local water depth. Tidal information was
             obtained from a VIMS report (Boon et al., 1978). For the boundary between different tidal
             stations, linear interpolation techniques were employed to achieve a smooth transition of the
             MTR. Table 5 presents the MTR for each submap (see Section 5 for submap locations).


             4.3     Storm Surge
                 During each storm event, the wind stress field on the water surface will also create an
             increase in local water level, i.e. the storm surge. The statistical distribution of the directional
             wind speed and resulting hindcast wave field is not identical to the storm surge probabilities
             although the two factors (waves and water levels) are related.
                 Table 4 of the 62 major storms between 1956 and 1978 also includes measured, maximum
             storm. surge for Virginia Beach, Virginia. These values are plotted in Figure 19 which shows
             that the mean storm surge was 2.6 feet with a 0.94 foot standard deviation at the 95 percent
             confidence level. A histogram of these storm surge events is plotted as Figure 20. The greatest
             number of storms (23) were in the 2.0-2.5 feet class interval.
                 A formal, statistical analysis of extratropical, storm surge heights for the five primary tide
             stations on the Bay can be found in Boon et al., 1978 (Figure 7.7, p. 107). For a 2.5 feet surge
             the annual exceedance frequency varied over the Chesapeake Bay. It is at the 0.65 level for
             Hampton Roads (Sewells Point), drops to only 0.05 at Solomons Island and then increases again
             to 0.25 at the Baltimore tide gauge. For ease in analysis, it was decided to use a uniform 2.5



                                                              31








            7.0
                                            MEAN = 2.60 ft
                                            STANDARD DEVIATION 0.94 ft

            6.0





            5.0

          rX4     - - - - - - - - - - - - - - - - - - - - - - - - -

          PQ 4.0


                                                                        Ld

                                                                        z
            3.0                                                         LIJ
          W4                                                  MEAN      U

                                                                        LA
          U)                                                            z
            2.0                                                         0


                                                                        U-)


            1.0


                  - - - - - - - - - - - - - - - - - - - - - - - - -





              1955        1960       1965        1970       1975        19,80
                                          YEAR

                Figure 19 The Historical Records of Storm Surge, Virginia Beach (1956-1978).







                      25







                      20-



                  F-4
                  z


                      15-

                  @Z4     -
                  0




                      10-








                       0                        1 FIFT-T-T-,-T7@,       III III--T-TI 11
                         0.0    0.5     1.0     1.5    2.0     2.5     3.0    3.5     4.0     4.5     5.0    5.5     8.0     6.5
                                                CLASS INTERVALS OF STORM SURGES (FEET)
                          Figure 20 The Histogram of Storm Surge, Virginia Beach (1956-1978).








             Table 5 The Average, Mean Tidal Range for Each Submap.


                       Submap No.                                  Mean Tidal Range, R (feet)

                              1                                               R = 2.3 -

                                                                  Potomac River            R = 1.5
                              2                                 Rappahannock River          R      2.1

                              3                                               R = 1.7

                              4                                               R = 2.8

                              5                                               R = 2.2

                              6                                               R = 2.5

                              7                                               R = 2.6
                              8                           York River and Mobjack Bay              R     2.5
                                                            Piankatank RiverArea                R      1.2

                              9                                               R = 1.9

                              10                                              R = 1.4

                              11                                              R = 1.6

                              12                                              R       1.6












                                                                                              S=2.S(ft)
                                                                                           I Z*=MTR/2
                                                                                                                  MLW



                                                            h
                                                                               'jMLW         d(x)
                          MTR a Mean TTid
                          MLW a Mean Low We
                          S a Storm Surge Height
                                                         - - - - - - - - - -                 - - - - - -
                          d (x) -z Local Water Depth





            Figure 21 Definition Sketch for Water Dep              th.


                                                                     34









             feet storm surge for all mean water depth calculations over the entire Bay and tributaries. This
             storm surge level can be considered as arising from a moderate storm event with a similar
             probability of exceedance as that for the wind speeds.


             4.4    Mean Water Depths
                 The mean water depth is defined as the summation of the weighted-averaged water depth
             below MLW along the wind fetch, plus half of the mean tidal range, plus the storm surge height.
             Weighted-averaged water depths along each dominant fetch direction are found by summing the
             products of each local depth times its individual fetch length and dividing the total by the fetch.
             length in that direction. This is the most time consuming aspect of the entire study. Figure 21
             is a definition sketch for the vertical elevation. The mean water depth, @i for ACES application
             is defined as
                                                &Lw + ZO + 2.5 , z* = MTR12                           (1)


             4.5    Submaps for Display of Results
                 The bathymetric chart of the Chesapeake Bay by VIMS (1977) at a scale 1         224,700 (one
             inch equals 3.5465 miles) was utilized as the basis for developing a series of submaps of wave
             information. Twelve submaps were established to cover the Chesapeake Bay and the major
             tributaries. Each submap is on 8.5 inch by 11 inch paper with half-inch margins so that each
             submap, will be 7.5 inch by 10.0 inch. Figure 22 shows submaps numbering (No. 1 - 12) of
             Chesapeake Bay and adjacent area. Map numbering begins with No.1 covering the headwater
             of the Potomac River at Washington, D.C. and ends at No. 12 which covers the entrance region"
             of this same river. Table 6 is the submap coordinate system in which coordinates of the top Oeft,
             right) and bottom (left, right) for each submap to the nearest degree, minute, and second in
             latitude and longitude are presented. Submap No.8 was selected as the test case to study the
             entire methodology for wave information development as discussed in the following section of
             this report.












                                                            35











                             77000'                                7600                            75000'
                                                                       0'












                        Washington, D.C.
           3
            90
              00'





                                                      0



                                   _E2






                                                 N
                                     04@
                                         0
          38000'                                                                               Maryland
                                        r   S,          0
                                                                                           Virginia


                                     4
                                        00


                                                        8   lb

                                     57
                  IAI











          37000'
                                                         Z

                                                      ZZLI


        Figure 22 Numbered Submaps for Chesapeake Bay and Adjacent Water Bodies.
                                                          36








              Table 6 Submap Coordinate System.

                Submap No.           TOP Left         Top Right       Bottom Left Bottom Right                Remarks
                           La.     380 55' 37"      380 55' 37"       380 32' 30"       380 32' 30"        Scale

                           Lo.     770 25' 47"      760 45' 56"       770 25' 47"       760 45' 56"        1:224,700
                   2       La.     380  32'  30"    380   32'  30"    380  09'  01"     380   09' 01"
                                   770  25'  47"    760   45'  56"    770  25'  47"     760   451 56"      1 inch

                           La.     380 09' 01"      380 09' 01"       370  45' 59"      370   4515911      3.5465 mile.
                   3
                           Lo.     770  25' 47"     760   45' 56"     770  25' 47"      760 45' 56"

                           La.     370  45'  59"    370   45' 59"     370  23'  03"     370   23' 03       La = latitude
                   4
                           Lo.     770  25' 47"     760   45' 56-     770 25' 47-       760   4515611      Lo=longitude

                           La.     370  27'  23     370   27' .23     370  04'  05"     370   04' 05"
                   5
                           Lo.     770  25' -47"    760   45' 56"     770  25' 47"      760 45' 56"
                   6       La.     370  14'  16"    370   .14' 16"    360  50' 48"      360   501 48"      *Use Top and
                           Lo.     760 51' 43"      760   11' 54"     760  51' 43"      760   1115411      Left Scale

                           La.     370  14'  16"    370   14'  16"    360 50' 48"       360   5014811      on the Map.
                   7
                           Lo.     760  17'.36"     750   37'  36"    760  17'  36"     750   37' 36"

                           La.     370  35' 24"     370   35'  24"    370  12'  12"     370   12' 12
                   8
                           Lo.     760  51' 43"     760   11' 54"     760  51'  43"     760   11' 54"

                           La.     370  35' 24"     370   35'  24"    370  12'  12"     370   12' 12"
                   9
                           Lo.     760  17' 36"     750   37' 36"     760  17' 36"      750   37' 36"

                           La.     370  58' 20"     370   58'  20"    370  35'  24"     370   35' 24"
                   10
                           Lo.     760  51' 43"     760   11' 54"     760  51' 43"      76"   11' 54"

                           La.     370  58'  20"    370   58'  20"    370  35'  24"     370   35' 24"

                           Lo.     760  17'  36"    750   37'  36"    760  17'  36"     750   37' 36"

                           La.     380  17'  15"    380   17'  15".   370  54'  001,    370   54' 00"
                   12    -
                           Lo.     760 51' 43"      760   11' 54"     760  51' 43"      760   11' 54"







                                                                     37









             5.0 TEST CASE DEVELOPN[ENT - SUBMAP NO.8


             5.1     Grid Scales and Application of ACES 1.07
                 Submap No.8 was selected to use as the test case. Figure 23 shows the boundaries of this
             map and the grid employed to make wave hindcasts at each node on the grid. A grid scale of
             one centimeter by one centimeter (1 cm M 1.4186 mile in actual) was used for the relatively
             broad Bay area. However, for the narrow York River area, finer grid sizes were employed.
             Approximately one hundred grid points were selected to estimate fetch information, mean water
             depth, and wave information. Design wind speed of 35 mph with 6 hour duration was employed
             based upon the storm probability analysis. However, for South-East winds over the York River
             a wind speed of 25 mph was employed because it has the same design exceedance probability.
             A storm surge height of 2.5 feet was used. Also, a MTR of 2.5 feet was used for the York
             River and Mobjack Bay area, and a MTR of 1.2 feet was used for the Bay and the Piankatank
             River area. In order to apply the ACES wave hindcast model, the selection of the fetch condition
             (open or restricted fetch) and the determination of the mean water depth are essential. These are
             discussed in the following sections.


             5.2    Restricted Fetch Versus Open-Water Fetch Results
                 In open water, wave generation is limited by the dimensions of the meteorological event
             under investigation and fetch widths are of the same order of magnitude as the fetch length. The
             restricted fetch methodology applies the concept of wave development in off-wind directions and
             considers the shape of the basin.
                 Tests at several nodes in Submap No.8 were conducted using both the open-water and
             restricted fetch modes of wave hindcasting in ACES 1.07. Open-water conditions produced
             larger wave heights than restricted fetch condition: on the order of 0. 1 to 1. 0 foot for the test
             nodes. However, the open-water fetch condition is not suitable because open-water conditions
             with fetch width equal or greater than fetch lengths are generally not found in the Chesapeake
             Bay for the-dominant fetch distances involved.


             5.3     Variable Water Depth Results
                 ACES 1.07 requires constant water depth along the fetch distance. Therefore, a weighted-
             averaged method is employed to calculate the representative, mean water depth. Weighted-
             averaged water depths along each dominant fetch direction are found by summing the products



                                                             38





                                                                                                                                                             Loomiss                                                                                                  L8

                                                          CA
                                                                                                                                                                             W//*, >            StUf5 0- -10e
                                                                                                                              100                                                                                                fin ray Point
                                                                                                                                                     coadh,
                                                                                                                                                                       01 9%
                                                                                                                                                                                      1@              ?
                            -37 0'                             0, Ct                                                                                                             :7-7o L- =r,,
                                           a                                                                                                                                                          t.


                                                                                      A
                                                                                 Polo                                                                                                                                 WU cr


                                                                                                                                                                                                                          wt                                 ITI


                                                                                            cr


                                                                                                  Cr
                                                                                                                                                                                        z          W."",                                                     rn
                                                                                                                                                                                      73:
                                                                                                                                                                                            L



                                                                                                                                                               I      ILI
                                                                             Fo"                                                                                                                              r,       ,Orn
                                                               Almho Cr
                                                                                                                                        .?dA
                                                               .4-

                                                                               f
                                                                    0          f                                                                                                                       CK
                           -37020'                                                                                                                                                              BA r
                                                   Wallet Pond            Op                                                                                                                                             Ipw
                                                                                   Q                                                                                   M, Sells       I
                                                                             Quee                                                                  @addws


                                                                                                    4e                                                                 N-k
                                                                             Jon" Pond
                                                               Williamsburg                                                                                                   VI.           a
                                                        Submap 8
                                                                                                                                                                                                 S-f5
                                                                                                                                                   Ito














                                York River and Mobjack Bay                                                                                        1@30'                                                      7;020'

                          Figure 23 Grid System for Submap No.8









             of each local depth times its individual fetch length and dividing the total by the fetch length in
             that direction. Tests at several nodes in Submap No.8 were conducted using both (1) the
             averaged-depth over the dominant fetch direction, and (2) the averaged-depth over all the radial
             fetch distances. The restricted-fetch method using averaged-depth over the dominant fetch
             distances produced slightly higher wave heights than when the depths are averaged over all the
             radial fetch distances. For this project, the averaged-depth over the dominant fetch direction was
             selected. This is the suggested method in the ACES 1.07 documentation, requires far less work
             and produces slightly more conservative, yet realistic results.


             5.4    Composite Wave Height Map
                 The wind direction is assumed to be identical with the longest fetch direction. Therefore,
             wave heights at the points of interest are the maximum possible from all directions under the
             design wind speed.
                 Figure 24 shows a wave information map with iso-wave height contours (spectral significant
             wave height, H.J at one-half foot intervals covering all the water areas on Submap No. 8. Wave
             periods (peak spectral periods, TP) associated with these wave heights appear below the wave
             heights in parenthesis. Figure 25 presents a relationship between the spectral significant. wave
             height and wave spectral peak period under the design wind speed, U", = 35 mph. This
             relationship was obtained from the wave heights and wave periods using ACES at all grid points
             in Submap No.8.


             5.5    Conclusions
                 In general, the wave hindcasting results for Submap No.8 are reasonable because major
             changes in wave height are hindcasted fairly well. A coarser sub-grid could have been employed
             for the broad Bay area but the finer sub-grid is still needed for the narrow York River area.
                 It was concluded that the restricted-fetch method using a weighted-averaged water depth over
             the dominant fetch direction provides the most reasonable wave information for enclosed bays,
             estuaries and river areas. These methods were applied to all other submap regions.










                                                             40










                                                                                                                                     LockOOCI

                                                                                                                                                                                     55
                                                                                                                                                                   P&* cr


                                                   CA

                                                                                                                              GSct% pt                                                     St ray Pdm



                                                                                                                                                                                   so
                                                   110,Jd*V G'                                                          14                                Cobbs Cr                 (45)
                          -3    030'


                                                                                                                                                                                                                  nj
                                                                CX    Polo                                                                                                                                (52)    to
                                                                                                                                                                                   Sims Cr



                                          W                                                                                                                                                                       rn


             41-                                                       T                                                                                                                                          ;FN
                                                                               ebw Cr                                                                                                                             rn

                                                                                                                                            4%*
                                                                                        "gel,
                                                        somv C(   Fe rnyWy                                                                                                  cc
                                                            0    S4                                   6                                                      MOBJACK
                                                                                                                                            %C*
                             37*20'                                                                                                                              BA Y

                                              W&Wr Pow

                                                                                                                                               SOem River                                                 6.6
                                                                                                                           saddIG" t4ec@'                                                                 15.2)


                                                                        Pond                                                                Nec*
                                                                                                                                                            I      % 00
                                                      WHIlamsburg                                                                                            0                                     0
                                                                                                                                                  jenkho 140-1                                    10)                 7.0
                                                                                                                                                         5.0
                                                 Submap 8                                        46'                                                    (4.51
                              York River and Mobjack Bay                                                        Yorklown 76                                                 76*20'
                         Figure 24 The Wave Information Map for Submap No-8 Showing Iso-Wave height Contours With Wave Periods in Parentheses.











                                      rn  5-

                                     E--4



                                      0

















                                     CO










                                                0                     1                    2                    3                     4                     5                    0                     7
                                                                                                  Significant Wave Height, Hmo (ft)
                                                Figure 25 The Relationship Between H. and TP for Uw = 35 mph.










            6.0 DEVELOPMENT OF WAVE INFORMATION MAPS



            6.1    Discussion
                Each submap was treated in detail, since errors on one could alter the results for adjacent
            areas. All submaps were combined on one large layout to insure that all wave heights were
            consistent from region to region on each submap. The submaps show iso-wave height contours
            at one-half foot intervals with wave periods covering all the water area with the fifty percent
            exceedance probability wind speed in any one year. Wave heights less than one foot are not
            shown. Wave height contours were obtained by linear interpolation among each adjacent node.
            Also, wave periods associated with each wave height were obtained from the statistical results
            of ACES output for the Submap No. 8 as shown in Figure 25. Submap No. 8 included all possible
            conditions encountered and the results shown in Figure 25 were also spot-checked for wave
            period throughout the study.


            6.2    The Final Product
                All final wave information maps with submap numbering are included as the Appendix for
            this report. Map numbering begins with No. 1 covering the headwaters of the Potomac River at
            Washington, D.C. and ends at No. 12 which covers the entrance region of this same estuary.


            6.3    Limitations
                The ACES hindcast model is a simplified, wave generation model that assumes a constant,
            weighted-average water depth over the entire wind field region'. Because water depth is a key
            independent variable for wave transformation over two-dimensional bathymetry, this assumption
            is a primary limitation of the ACES methodology. Variable water depths permit the     waves to
            shoal and refract and these transformations must be empirically incorporated within the
            calibration coefficients of the wave formulas employed. Wave energy spreading is also not
            explicitedly controlled by the user of the ACES model.
                Near the shoreline, wave breaking and energy loss further complicates the process.
            Therefore the wave height contours presented should not be used at the shoreline. Surf zone
            energy loss models must be used in this region. These models must include shoaling, refraction,
            wave breaking energy loss, and wave induced set up on the local water levels.
                In the center of the Bay near the lower end where fetch distance is greater than 75 miles,
            the height contours become aligned with the dominant fetch direction because wave height


                                                          43








             becomes controlled by mean water depth, not increasing fetch distance. This illustrates the point
             that the contours depict the largest waves at each location that could result from all possible wind
             directions. At some locations shorter fetch distances over deeper water produce bigger waves
             than that from. the longest fetch direction.
                 Wave heights (and periods) in Submaps No. 6, 7, 8, and 9 do not include waves from distant
             .storms which enter the Bay from the Atlantic Ocean. Recent wave data measurements by Dr.
             John Boon at the Virginia Institute of Marine Science in the lower Bay at Thimble Shoal Light
             (Submap No.7) have shown double Peaked energy density spectrums. Higher frequency energy
             associated with storm waves comes from the north and lower frequency energy associated with
             swell waves comes from the Bay entrance. This study only considers the storm wave component
             in the energy density spectrum and the associated spectral significant wave height and peak
             spectral period.


































                                                             44









             7.0 CONCLUSIONS AND RECONDIENDATIONS



             7.1    Conclusions
                 Much of the 5,000 mile shoreline of Virginia around the Bay consists of relatively moderate
             property value (farmland, single family dwellings, etc.) and this translates into relatively
             moderate wave energy levels for the design of coastal shore protection alternatives. From the
             historic wind data analysis, the design wind speed of 35 mph was selected which has about a 50
             percent probability of exceedance in any one year. These can be considered for design to provide
             minimum property protection.
                 Submaps No. 1 through No. 12 in the Appendix present iso-wave height contours and
             associated wave periods for the Chesapeake Bay and its major tributaries in Virginia. Maximum
             wave heights were 8 feet with periods about 5.8 seconds and are found near the middle of both
             the upper and lower reaches of the Bay. Wave heights decrease along the tributary rivers. Wave
             heights less than one foot are not shown.
                 The design wave information presented on these twelve maps are considered to resonably
             reflect the results expected for the design wind conditions.


             7.2    Recommendations
                 These results are recommended for use in providing consistent, wave information climates
             for shoreline property owners around the Bay.
                 Results shown on submaps near the entrance to Chesapeake Bay (6,7,8, and 9) do not
             include ocean waves propagating into the Bay. It is recommended that a second phase of this
             study be initiated using the parametric, spectral wind-wave model MIKE 21 NSW that is
             presently installed in the Computing Laboratory of the CE Department at ODU. This two-
             dimensional model can study how ocean wind-waves from coastal storms and ocean swell waves
             propagate into the Bay. The combined results can then be incorporated into an updated version
             of Submaps 6,7,8, and 9. for the entrance region of the Bay.
                 The spectral wind-wave model MIKE 21 NSW can also be used to make site specific,
             nearshore wave transformation studies (shoaling, refraction, etc.), including energy losses due
             to surf zone wave breaking. Boundary conditions for fine-grid, two-dimensional models can be
             the results of this study or generated separately from a large grid model of the entire Bay that
             is presently under development.
                 Finally, it is recommended that for locations where shoreline erosion threatens high value


                                                           45








            property such as public infrastructure (roads, pipelines, transmission lines, etc.) or private
            property (major buildings, marinas, etc.) that site specific, coastal engineering studies be
            conducted to determine the appropriate probability level for the design wind speeds. Higher
            value property will suffer larger damages during storm events so that it may be economically
            feasible to consider rarer storms with stronger winds for these situations. Thus the design wave
            information as presented on the submaps of this report are specifically for the Shoreline
            Programs Section of the Department of Conservation and Recreation of the Commonwealth of
            Virginia and are not recommended for general design use for all coastal engineering problems
            around the Bay.







































                                                           46










                                                 REFERENCES



            Automated Coastal Engineering System (ACES), US Army Corps of Engineer, CERC, Version
               1.07, Jan., 1992.
            Boon,J.D., Welch,C.S., Chen,H.S., Lukens,R.J., Fang,C.S.,and Zeigler, J.M.,"A Storm Surge
               Model Study. Volume I. Storm Surge Height-Frequency Analysis and Model Prediction for
               Chesapeake Bay", Virginia Institute of Marine Science, 1978.
            Chesapeake Bay Shoreline Erosion Study, US Army Corps of Engineers, Baltimore District,
               Norfolk District, 1990.
            Goldsmith,V., Hennigar,H.F., Gutman,A.L., and Blake,N.T., "Coastal Processes and Resulting
               Forms of Sediment Accumulations Currituck Spit, Virginia-North Carolina", Field Trip
               Guidebook, Virginia Institute of Marine Science, Gloucester Point, VA., 1977.
            Hasselmann,K., Ross,D.B., Muller,P., and Sell,W.,"A Parametric Wave Prediction Model".
               Journal of Physical Oceanography, Vol.6, pp.200-228, 1976.
            Ho,F.P., Tracey,R.J., Myers,V.A., and Foat,N.S., "Storm Tide Frequency Analysis for the
               Open Coast of Virginia, Maryland, and Delaware", NOAA Tech. Memo. NWS HYDRO-32,
               Silver Spring, Md., 1976.
            Holthuijsen,N., Booij,N., and Herbers,T.H.C.,"A Prediction Model for Stationary, Short-
              Crested Waves in Shallow Water with Ambient Currents", Coastal Engineering, Vol. 13,
              No. 1, pp. 23754, 1989.
            Jensen, R.E., and Garcia,A.W., "Wind, Wave and Water Level Assessment for the January 4,
               1992 Storm at Ocean City, Maryland", Shore and Beach, January, 1993.
            MIKE 21, Nearshore Spectral Wind-Wave Module, Release 1.2. User Guide and Reference
               Manual, Danish Hydraulic Institute, Denmark, 1992.
            Pore,N.A. and Richardson,W.S., "Storm Surges at Hampton Roads (Sewells Point), Virginia".
               in Coastal Processes and Resulting Forms of Sediment Accumulations Currituck Spit,
               Virginia-North Carolina, Field Trip Guidebook, Virginia Institute of Marine Science, VA.
               1977
            Senate Document No. 4, "Report of the Coastal Erosion Abatement Commission to the Governor
               and the General Assembly of Virginia", 1979.
            Smith,J.M. , "Wind-Wave Generation on Restricted Fetches",MP-CERC-91-21 US Army Engineer
               Waterways Experiment Station, Vicksburg, MS, 1991.
            Shore Protection Manual (SPM), US Army Engineer Waterways Experiment Station, CERC,



                                                        47









              US Government Printing Office, Washington, DC, 1984.
           Vincent,C.L.,"Deepwater Wind Wave Growth with Fetch and Duration", MP-CERC-84-13, US
              Army Engineer Waterways, Experiment Station, Vicksburg, MS, 1984.
           Virginia Institute of Marine Science (VIMS), Bathymetry of the Chesapeake Bay, 1977.(map)










































                                                     48








                                            APPENDIX





                                  WAVIE MORMATION M"S

                             FOR CBESAPEAKE BAY IN VIRGE14U









                           Wind Wave Hindcast For Sustained Wind Speed At The 50
                             Percent Exceedance Probability Level, U,, 35 mph













             Scale     1 inch   3.5465 miles
             Date      December, 1993
             Notes     1. Wave heights and periods (in parenthesis) are in general,
                         generated along the longest fetch at the point of interest.
                             H,..   Spectral significant wave height,
                              Tp    Peak spectral period,
                       2. Bathymetry from VIMS (1977) chart.
                       3. Storm surge height is 2.5 feet.







                                                   49














                                  77000'                                     76*00'                              75000'













                            Washington, D.C.
             3
              90
                 00'





                                                              0




                                           L2




                                            NI



                                            3


                                                                   CD
             38000'                                                Eh                                       Maryland

                                                                                                         Virginia


                                           A



                                                                8

                                                                    NZ













             37*00'
                                           ED                                      F71


         Numbered Submaps for C         hesapeake Bay and Adjacent Water Bodies.











                                        77020'                                       77010'
                                                                                                                   Washington, D.C.












                           38050'

                                                                                                         Alexandria










                                                                                                                          2.0
                                                                                                                          @2.7)
                                                                                                                                Bra




                                                                                                                                wa/I
                                                                                                                    Fo
                                                                                                            S       Hunt.


                                                                                                                                    Q-




                           38'40'


                                                                          Be Ont
                                                                             Say
                                                                                       Hallowin pt

                                                                     Ocwquan
                                                          CO C'        Say ) HI           2.5,1/
                                                                                         (3.1)



                                                                           3 -0
                                                                           (34       SCI* .
                                                                                                                                                  Submapl
                                                                                                                     Potomac River Near Was
                                                                         :"Madaw"O







                                          77-@O,                                               77010'                                                77000'
                                       CAbp       Shoong pt
                                                   Cr


                           38030'


                                                       3,0
                                                      (3.4)


                                                                    Liverpool Pt


                                                                     Douglas Pt
                                                         3.0                                                             me
                                                                                                                               U
                                                         (3.4)

                                                                                  A

                                                                      Smith Pt                                                       2.5
                                                                                                                                    (3.1)
                                                                        Clifton                         GO
                                                                        Beach                      10,111, .                                               ..                    , ,  :
                                                                                                                                       Mathias
                                                                                                                         25             Pt                                                         0
                                                                             (nas lot

                                                   0
                                       -4-ok.-k C,
                                                                                                                        kC(
                                                                                                                             -01, Zap  90                                   pt
                                                                                                                                                                      COV
                                                        'Bull                                                                                               3.0        PACCOW&C
                                                                                                                                                                               S
                          .38*20                                                                                                                            (3@4)
                                                        Bluff


                                            p                                                                                                                         3.5
                                                                                                                                        Baber
                                                                 0       M      A       C                                                 pt                         (3.7)


                                                                                                                           MachDdoo Cr



                                                                                                                                                                                    4.5
                                                                                                                                                  Colonial                          (4.2)
                                                                                                                                                   Beach

                                                                                                                                                     Monroe Cr


                                                             Submap 2                                                                                             Church
                                    Potomac River                             Middle Reach                                                                          pt


                           38010'











                                        77020'                                                    77010,                                                77000'


















                                                                                                                                                                                                  CA


                                                                                                                                                                                                       C11

                             38000'
                                                                                                                                                                                           20
                                                                                                                                           0                                              (27)


                                                                                                                                                                                          Z
                                                                                                                                                                                            pf         1.5
                                                                                                                                                                                                       (2.3)

                                                                                                                                                                                       "Ov C,


                                                                                                                                                                                    Tappahannock

                                                                                                                                                                                                          of








                                                                                                                                                                                                        Pisca





                             37050'
                                                                   Submap 3
                                 Rappahannock River - Upper Reach











                          77020'                              77010'                               77000'














                    37W'
























                    37030'






                                               Submap 4
                      York River,           Upper Reach at West Point











                            77020'                                        77010'                                        77"00'                                          760








                                    0

                                      0

                                                                                                                                -410
                                                                                                                                     4f11V

                                                            Kims so C,
                                                                           He,
                      37020'


                                                            0                                  2.0
                                                                                              t2
                            A,"\ OX R I V E
                                                                      Be
                                   Hopewell                              y


                                                                                                                                1:3
                                                                                                                                2



                                                                                                                                       2.
                                                                                                                                       2.7
                                                                                                                                                                       2.5
                                                                                                                                                                      (3.0)

                                                                                                                             Claremont








                      37010'




                                                          Submap 5
                           James River - Upper Reach to Hopewell













                                                               r        I
                                                                    76040'                                             76030'                       5.0                     76020'
                                                                                                                                                    (4.5)
                                            Mill cf                                                        YORKTOWN                                                  5.5
                                                                                                                                                                     (4.7)
                                                                                                                                        G     ,ck Cr
                                            Ja    stown                                                                                  cf.
                                                                                                                                                     q6
                                                                                                                                                                                6.0
                                                           2.6
                                                          (3.0)                                                                                                                (5.0)
                                                                    14-
                                                                               3.0                                                            Han Z.
                             37'10'             Cobham Bay   -    I
                                                                   Island     (3.4)


                                                                                         Ot


                                                                                                      Its-




                                                                                                                    'pCr


                                                                                                     15
                                                                                                     (3.7)
                                                                                                                      ehint pf





                                                                                                                                                                         /*
                                                                                              DaA.41@
                                                                                                                   36
                                                                                                                  (3.7)
                             37oOO'                                                                                                                             HAMPTON'


                                                                                                                                                                              6.6
                                                                                        .p    Rw
                                                                                                                                                NEWPORT.
                                                                                                                                                   NEWS,                     (4.7)


                                                                                                                                         1_4r5r
                                                                                                                                     4.0
                                                                                                                                    ('1.0)   (4.2    5.0                 4.5
                                                                                                                                                    (4.5)                (4.2)




                                                                                                               Cr                                                    r
                                                                                                                                                                                     La"syeft.
                                                                                                                                                                    D    I
                                                                                                                                                                     Arsa
                                                                                                                              91
                                                     Submap 6
                              James River - Entrance to Bay                                                                                          PORTSMOUTH












                                                                                                                                                                       Gr
                                                                                76'10'                                                                                                                                          7@


                                                                                                                                                              Riots Cr




                                         6.5
                                         (5.2)                                                                          8.0                                                                  eft


                                         37010'
                                                      TO
                                                      (5.4)                                                                                                                                  eb


                                                                                                                                                                                                          0

                                                                                                                                                               8*0
                                                                    7  5                                                                                      (5.8)
                                                                    (6.7)                                                                                              Cape Charles





                                                                                                                                                                                                                                          CAUTION
                                                                                                                                                                                                                         Does not include ocean sv



                                                                    7.6
                                         37000'                     (6.7)                     8.0                                                     A.0
                                                     7'0                                                                                             (5.8)










                                                                       Cr

                                                                                                  Lake                                                                                                                                    Submap 7
                                                                                                 Joyce..,.
                                                           to-.                                                                                                                  Atlantic Ocean Entrance to Ch












                                                                                                                                                         LockfisS GI

                                                                                                                                                                                                                 5.5
                                                                                                                                                                      of                  tj Psrk Cr             (4.7)


                                                                                                                                                                                          sturgooo
                                                                                                                                                  cwh


                                                         Of                                                                                                                                                   5.0
                                                                                                                                                      k6                                                      (4.5)
                                                                                                                                                                                  Cobbs Ct
                                                            HOCWO
                                -37 30'

                                             To                                                                                                                                                     Cr



                                                                                                                                                                                                              SAX$ Cr







                                                                                            C,

                                                                                             Hkjw C,



                                                                  -VAyflyno cr                                                                                                                        cc        m
                                                                             Ferry                              0
                                                                  .A-
                                                                      0         r                                                                                                    MOBJACK
                                -37020'                                                                                                                            6-k                    BA Y
                                                      WatlorPond                                                                  e                                  Ssw@ RFVv8f
                                                                              Quee                                                             S&dMts t4o'

                                                                              J"s Pond                                                                            Nork                          00

                                                                Willimsburg                                                                                              Jenkins N80
                                                                                                                                                                                5.0
                                                           Submap8                                                             a  YONO@wn                                       t4.5)
                                     York River and Mobjack Bay                                                                              760                                                      760,20,









                                                                            76010'                                                                   76000'                                                       Cr              75050'                                  Yl
                                                                                                                                                                                      '0
                                                                                                                                                                                   (6.0
                                                                                                                                                  75                          (
                                                                                                                      8.0                        (6'7)                         6.5
                                                                                               7.6                   (5.8)                                                    (6.2)               Occohann
                                                                                               (5.7)                                                              7.0
                                                                                                                                                                 (5.4)                Silyer
                                                                                                        8.0                                                                           Beach                                               01
                                                                                                       (5.8)
                                          37030'
                                                 6.5
                                                (6.2)


                                                                                    7 0
                                                                                   (6.43)
                                          0





                                                                                                                                                                                      jacobU9




                                                                                                                                                                                          Cr







                                                                                                                                                                      GUN


                                          37020'



                                               6.5
                                          6.6) I I
                                          (4.7 (6.2)
                                          6.01                                                           -0
                                          (6-0)
                                                                                                       (6-8)                                                   Cr
                                                                                               7.6                   (:.0
                                                                                               (5.7)                   -8)
                                                                                                                                                        Cap1bades
                                                             Submap 9
                                          Bay Lower Reach and
                                          0



















                                                       Eastern Shore                                                                                         016e














                                                                                                                                                                                                                                     .0
                                                                                         76040'                                                       76030'                                                            76020      (:.o)
                                                                                                                                                             8@                                                              \ 5.5
                                  Little Carter Cr                                                                                                                                                                             (4.7)
                                                                                                                                                      4@1
                                                                                                                                                      QF







                                                                roy
                               Lowery Pt-
                                                                                                                                                                                Great            COM/     .CO
                                                                       PA
                                                                 S491W
                                                                                                                                                                                                                  11'er


                                                                             C

                                 37050'



                                                                          2.0                                       6f                                                                                             Mill        Cr     Ingram
                                                                         (2.9)
                                                        0                                                           ry C1
                                                                                                                            Cr




                                                                                                         2.5
                                                                                                        (3.0)
                                                                                                                        3.0                  C@ -
                                                                                                                       (3.4)             6   0
                                                                                                                                             0 0                                                                                          6.5
                                                                                                    "Ift Gr                                                                                                                              (4.7)


                                                                                                          weeks C



                                 37040'

                                                                                                                                                                                                         Poplawr  eck
                                                                                                          Robinswon
                                                                                                                                                                   L&     X

































                                                                                                                                                                       Orcha   Pt                                            Uffle Bay
                                                 Submap 10                                                                 6
                                   Rappahannock River                                                                                                         5.0
                                                                                                                                                             (4.5)
                                          Entrance to Bay                                                                                                                                                                                 W1
                                                                                                                                                                                                           Mosquifto Pt













                                                                                                                                                                                                                      Crisfield
                                                                           76010'                                                               '7600

                                                                                                                                                            MD                                                                                                      Tulls

                                                                                                                     7.0
                                                                                                                    (5.4)


                                                                                                                                                   smith Is.









                                                            7  0                                                                                                                                                                                        6.0
                                                            (5,4)                                                                                                                                                                                      (6.0)

                                                5.5

                                   V37050'                                                                                                                                                                     6.0
                                                                                                                                                                                                               (5.0)


                                                                                                                                                            Tangier Is.                                                                        Gut



                                                                                                                                      70                                                        Watts Is.
                                                                                                        8.0                          (6.4)
                                                                75
                                                               (6-1)                                    (5.8



                                            6.6
                                           (1.2)                                                                                                                                             6 6                                                        k
                                                                                                                                                                                            (6.2)





                                      37040'          70                                                                         7.5
                                                      (6,4)                                                                     (5.7)

                                                                                                                                                                                                                    n9O
                                                                           Submap 11                                                                                         7.0                                    Cog
                                                                                                                                                                             6.4)
                                                                 Bay Middle Reach
                                                                                                                                                      tTa.





                                        Tangier Island and Eastern Shore                                                                                                                                                              Wachapreague












                                                                             76.
                                                                                  A'@                                               76"30,                                                 76"20'

                                                                 AG

                            0
                                                                           Op, 0 Day
                                                                                  art
                                                                                            06
                                                    p,

                                          (3.7)                                   (6.2)
                                          4.0
                                         (4.0)
                                                                                                                                                      Pt     :St. Marys
                                                                 cS   5.0           6.0                                                                         City
                                                                             6.6    (5.0)
                                                                 (4.2  .     (4.7)                                                                                                                         7.
                                                                     (46)
                          :.28   1 Or                                                                                                            C)L                                                      (5.
                             NominiCift                    Nomini
                                                             0ey                                                               05
                                                           "Bav


                                                                                               Coles
                                                                                               Nock

                                                                               G*
                                                  PRfarce C'.



                                                                                                            S.
                                                                 C-,
                                         0
                                                                                                             Sardy Pt Ned
                                                 0


                                                                                                          VMS A                                         6.0
                                                                                                                                                       (6.0)                                               6
                                                             C,                                                                                                                         Pt Lookout         (5
                                                                                               West                         Mice


                                                                                                                                Cher'  Pt
                                                                                                                                  'N
                            38000,                                                                                                                                                         (,.o
                                                                                                                                                                                              (5.0)
                                                                                                                                                                        6.5
                                                                                                                                                     River              (4.7)



                                                             Submap 1@
                                   Potomac River - Entrance to Bay





                                                                                                                            NOAA COASTAL SERVICES CTR LIBRARY



                                                                                                                            3 6668 14111912 5