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-Z TECHNICAL REPORT UM RSMAS NO. 82001 A MULTIDISCIPLINARY STUDY OF CARTAGENA BAY, COLOMBIA Part I. WATER MOTION AND RELATED PHENOMENA By JOHN D. WANG DIVISION OF OCEAN ENGINEERING ROSENSTIEL SCH60L OF MARINE AND ATMOSPHERIC SCIENCE UNIVERSITY OF MIAMI, MIAMI, FLORIDA Qc 993.83 .T4 no.82001 January 1982 A MULTIDISCIPLINARY STUDY OF CARTAGENA BAY, COLOMBIA Part 1. WATER MOTION AND RELATED PHENOMENA John D. Wang U . S . DEPARTMENT OF COMMERCE NOAA COASTAL SERVICES CENTER 2234 SOUTH HOBSON AVENUE CHARLESTON , SC 29405-2413 Division of Ocean Engineering Rosenstiel School of Marine and Atmospheric Science University of Miami, Miami, Florida C@' Q) '::::j- cm Supported by Grant No. 04-8-MOl-166 U.S. Department of Commerce NOAA, International Sea Grant Program /INN Property of CSC Library FORWARD Between 1975 and 1977 scientists at the Rosenstiel School of Marine and Atmospheric Science, University of Miami, were involved at the request of Colombian authorities in matters related to the apparent increasing degradation of the environment and resources of Cartagena Bay, especially those related to mercury and chlorinated hydrocarbon pollution. Local studies had been fragmentary and lacked the co- ordinated multidisciplinary approach needed to provide baseline data for development of a management plan for the Bay area. However, Colombian scientists, technicians and university students were dedicated and enthusiastic in wishing to protect and conserve the Bay environment and resources,, and thus were anxious to receive help and advice. Subsequently two events pointed to the need for urgent action and these were: (i) in mid-1977 the closure of the local alkali plant (source of mercury pollution) and (ii) the findings of the FAO-Swedish scientific team on the sources, nature and probable extent of con- tamination of the Bay. The International Sea Grant program became operational in 1978 and a proposal was submitted to that program for the University of Miami to assist Colombia, based on our earlier study of Cartagena Bay. The proposal entitled "Marine Resources and Environmental Sciences Training and Information Exchange Program in Colombia" was accepted for funding for a 2-year period from I November 1978 with a subsequent extension for an additional year (3 years in total). i The general objective of theproject, through a cooperative training program, was to enhance the capability of Colombian scientists and technicians to better deal with environmental and resources pro- blems in the coastal zone. The specific project objectives, on a cooperative basis were (a) to provide a short series of lectures/ seminars with'related discussion periods, on the principles of multi- disciplinary marine resourcesand environmental studies of tropical coastal areas such as Cartagena Bay, as well as by using case histories from other applicable areas; (b) to provide on-the-job training in the design, planning, execution and coordination.of field and laboratory programs to provide the data base necessary for development of management plans for the coastal environment and resources, through a broad-scale integrated study of Cartagena Bay. The first project objective was achieved with the successful holding of the training course at the Colombian Navy's Center for Oceanographic and Hydrographic Research, Cartagena, from 17-27 April 1979. The course consisted of 40 one-hour formal lectures, four each morning, followed by 3-4 hours of informal discussion each afternoon in two interchanging disciplinary groups (physical/chemical and biological). Thirty-five undergraduate students and ten faculty from seven Colombian universities and one research group attended with an'additional 20-25 persons (scientists, technicians, Naval Officers) ,..present each day. Lectures covered fields of. hydrodynamics, chemistry .of sea water and pollution, marine biology/ecology, pollution biology, marine geology and public affairs-. Some 21 instructurs were involved, 17 of them from Colombia. The second project objective was- to undertake, as a training pro- gram, a broad-scale integrated multidisciplinary study of the. environ- ment and resources of Cartagena Bay, The field work related to this study was completed in May 1981; analyses and interpretation of the data are continuing. This present report on "Water Motion and Related Phenomena" is the first to result from the overall program, . Support of the project from the International Sea Grant Program, NOAA, U.S. Department of Commerce, under Grant No. 04-8-MOl-166 is gratefully acknowledged, In addition, the financial and technical support of various groups in Colombia should be recognized in particular the Comision Colombiano de Oceanografia (CCO); Direccion General Mar:rtimay Portuaria (DIMAR); Centro de Investigaciones Oceanograficas y Hidrogrificas (CIOH); Fondo Colombiano de los Recursos Naturales Renovables (INDERENA); FundaciSn Universidad de Bogota Jorge Tadeo Lozano (Seccional del Caribe, Cartagena); Universidad de Cartagena. Sincere appreciation must be expressed to Captain de Navro (R) Josue C. Aguirre Serrano,.who was Port Captain, during the preliminary and project phases of the study, for his unfailing support and advice at all times. Williams_--- krAxw1-pal Investigator TABLE OF CONTENTS Page FOREWARD . . . . . . . . . . . . . . . . . . . . . . . . . LIST OF FIGURES . . . . . . . . . . . . . . . . . . . . . . . . . . vi LIST OF TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . ix LIST OF SYMBOLS . . . . . . . . . . . . . . . . . . . . x I . ABSTRACT . . . . . . . . . . . . . . . . . . . . . . . . . 1 2. INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . 3 3. TECHNOLOGY TRANSFER . . . . . .. . . . . . . . . . . . . . . . 7 3.1 Short Course . . .. . . . . . . . . . . . . . . 7 3.2 Salinity computation from temperature and conductivity . 8 3.3 Harmonic analysis . . .. . . . . . . . . . . . . . . . . 9 3.4 Modeling . . . . . . . . . . . . ... . . . . . . . . . . 10 4. DATA COLLECTION . . .. . . . . . . . . . . . . . . . . . . . 12 4.1 Canal del Dique . . . . . . . . . . . . . . . . . . . 12 4.2 Rainfall . . . . . . . . . . . . . . . . . . . . . . . . 14 4.3 Wind . . . . . . . . . . . . . . . . . . . . . . . . . 14 4.4 Tides . . . . . . . . ... . . . ... . . . . . . . . . . 14 4.5 Salinity - temperature - depth profiles . . . . . . . . 16 4.6 Drogues . . . . . . . . . . .. ... . . . . . . ... . . . 28 4.7 Currents . . . . . . . . . . . . ... . . . . . . . . . . 31 4.8 Turbidity . . . . . . . . . . . . . . . . . . . . . . . 34 5. ANALYSIS OF DATA ... . . . . . . . . . . . . . . . . ... . . 45 6. MODEL FORMULATION . . . ... . . . . . . . . . . . . . . . . 51 7. MODEL ADAPTATION TO CARTAGENA.BAY . . . . .. . . . . . . . . . .57 8. MODEL APPLICATION . . . . . . . . . . .. . . . . . . . . . . 60 8.1 Tidal flow . . . . . . . . . . . . . . . . . . . . . . 60 8.2 Southwesterly Winds . . . . . . . . . . . . . . . . . . 68 8.3. Northerly Winds . . . . . . . . . . . . . . . . . . . . 75 9. DISCUSSION . . . . . . ... . . . . . . . . . . . . . . . . . 83 10. CONCLUSION . . . . . . . . . . . . . . . . . . . . . . 85 ACKNOWLEDGEMENTS . . . . . . . . . . . . . ... . . . . . . . . . 87 iv Page REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . 68 APPENDIX A - Program for salinity from conductivity and temperature . . . . . . . . . . . . . . . . . 89 APPENDIX B - Program for harmonic analysis of tides . . . . . 91 APPENDIX C - Field data . . . . . . . . . . . . . . . . . . . 94 v LIST OF FIGURES Figure Page 2.1 Cartagena Bay. Defense Mapping Agency Chart COL261, Soundings in Meters . . . . . . . . . . . . . . 4.1 Canal Del Dique Discharge at Incora, Km 7. . . . . . . 13 4.2 Average Monthly Rainfall . . . . . . . . . . . . . . 15 4.3 Boca Grande Tides, Record Begins July 22, 1980 at 09:00 Hrs. . . . . . . . . . . ... . . . . . . 17 4.4 Boca Chica Tides. Record Begins September 16, 1980 at 10:30 hrs. . . . . . . . . . . . 18 4.5 Simultaneous Tidal Elevations at Boca Grande and Boca Chica . . . . . . . . . . . . . . . . . . . . 19 4.6 Hydrographic Sampling Stations in Cartagena Bay . . . . 20 4.7a. Salinity7Temperature Graphs. June 21, 1979 . . . . . .. 21 4.7b Salinity-Temperature Graphs. October 16, 1979 . . . . 22 4.7c Salinity-Temperature Graphs. May 5, 1980 . . . . . . . 23 4.7d Salinity-Temperature Graphs. October 28, 1980 . . . . 24 4.7e Salinity-Temperature Graphs. October 28, 1980 . . . . 25 .4.7f Salinity-Temperature Graphs. February 9, 1981 26 4.7g Salinity-Temperature Graphs. February 10, 1981 . . . . 27 4.8 Observed Drogue Paths . . . . . . . . . . . . . . . . . . 29 4.9 Velocity Plots (Hydrographs) at Boca Chica. October 18, 1979 . . . . . . . . . . . . . . . . . . . 32 4.10 Measured Velocities . . . . . . 33 4.11 Measured Velocities at'Punta Arenas. June 1981 . . . . 35 4.12 Measured Velocities at Punta Arenas. 20 m below Surface, July 1981 . . . . . . . . . . . . . . . ... . 36 4.13A Observed Turbidities . . . . . . . . . . . . . . . . . . 37 vi Figure Page 4.13b Observed Turbidities . . . . . . . . . . . . . . . . 38 4.13c Observed Turbidities . . . . . . . . . . . . . . . . 39 4.13d Observed Turbidities . . . . . . . . . . . . . . . . 40 4.13e Observed Turbidities . . . . . . . . . . . . . . . . 41 4.13f Observed Turbidities . . . . . . . . . . . . . . . . 42 4.13g Observed Turbidities . . . . . . . . . . . . . . . . 43 4.13h Observed Turbidities . . . . . . . . . . . . . . . . 44 6.1 Definition Sketch for Twolayer Model . . . . . . . . 54 7.1 Finite Element Grids for Cartagena Bay . . . . . . . 58 8.1a Predicted Tidal Currents in Cartagena Bay. Time = LW + 9000 sec. . . . . . . . . . . . . . . . 62 8.1b Predicted Tidal Currents in Cartagena Bay Time = LW + 18000 sec . . . . . . . . ... . . . . . . 63 8.1c Predicted Tidal Currents in Cartagena Bay Time = LW + 27000 sec . . . . . . . . . . . . . . . . 64 8.1d Predicted Tidal Currents in Cartagena Bay Time = LW + 36000 sec . . . . . . . . . . . . . . . . 65 8.le Predicted.Tidal Currents in,Cartagena Bay Time = LW + 45000 sec . . . . . . . . . . . . . . . . 66 8.2 Predicted Particle Trajectories for Tidal Forcing . . . . . . . . . . . . . . . . . . . 67 8.3a Predicted Currents in Cartagena Bay. Tide and SW Wind. Time = LW + 9000 4ec. . . . . . . . . . . 69 8.3b Predicted Currents in Cartagena Bay. Tide and SW Wind. Time = LW + 18000 sec . . . . . . . . . . . 70 8.3c Predicted Currents in Cartagena Bay. Tide and SW Wind. Time = LW + 27000 sec. 71 8.3d Predicted Currents in Cartagena Bay. Tide and SW Wind. Time = LW + 36000 see . . . . . . . . . . . 72 8.3e Predicted Currents in Cartagena Bay. Tide and SW Wind. Time = LW + 45000 sec . . . . . . . . . . . 73 vii Figure Page 8.4 Predicted Particle Trajectories for Tide with SW Wind . . . . . . . . . . . . . . . . . . . 74 8.5a Predicted Currents in Cartagena Bay. Tide and N Wind. Time LW + 9000 see . . . . . . . . . . . 76 8.5b Predicted Currents in Cartagena Bay. Tide and N.Wind. Time LW + 18000 see . . . . . . . . . . . 77 8.5c Predicted Currents in Cartagena Bay. Tide and N Wind. Time LW + 27000 see . . . . . . . . . . . 79 Predicted Currents in Cartagena Bay. Tide and N Wind. Time LW + 36000 see . . . . . . . . ... . 79 8.5e. Predicted Currents in Cartagena Bay. Tide and N Wind. Time LW + 45000 see . . . . . . . . . . . 80 .8.6 Predicted Particle Trajectories for Tide with N Wind o . . . . . . . . . . . . 81 viii LIST OF TABLES Table Page 4.1 Wind speed and direction during drogue experiments . . . . . . . . . f . . . . . * . . . . 30 1. t ix LIST OF SYMBOLS A surface area Cl chlorinity C f bottom friction coefficient C 1 interfacial friction coefficient C D surface wind drag coefficient Eij eddy viscosity coefficients f Coriolis parameter F force measures g gravity acceleration H tidal range H 1 bottom layer depth H 2 surface layer depth Ks conductivity P pressure P tidal prism q1x'qly and q2x'q2q layer discharges in x and y direction Q F freshwater discharge S salinity t temperature T temperature anomaly, Chpt. 3 T flushing time, Chpt. 5 u,v x and y velocities x U 10 wind speed 10 m above surface V F fresh water volume per tidal cycle V T total volume of top layer n i bottom, interface and surface elevation i = 0,1,2 p density -- density difference - stress term xi 1. Abstract An interdisciplinary project is undertaken with the objective of training Colombian personnel in dealing with pollution impact in coastal and estuarine waters. This goal will be approached through the transfer of technology from University of Miami in the form of formal and informal short courses and practical experience by involvement in a baseline study of Cartagena Bay. The accomplishments and findings described in this report result primarily from the hydrodynamic effort while water chemistry, biological chemistry, biology,'and geology are described in parallel reports. To introduce the Colombian trainees to coastal hydrodynamics a series of 10 lectures were presented in April 1979 at the Center for Oceanographic and Hydrographic investigations (CIOR) in Cartagena. These lectures were followed by several seminars covering the theory, data collectionsdata analysessand modeling throughout the duration of the project. A field sampling program is designed to monitor the main variables; currents, salinity-temperature, tides and turbidity on a regular basis. The collected data show that the hydrodynamic characteristics of the Bay are strongly influenced by the freshwater inflow of the Canal del Dique. During periods of significant canal discharges the Bay exhibits a two layer stratification. This stratification is of major importance in understanding and describing the flow patterns in the Bay 2 as driven by tides and wind. twolayer vertically integrated finite element model is adapted to the Bay and applied to typical tide and wind forcing con ditions., The tides-effect a slow flushing on the order of 10.days in the surface layer while minimal flushing is found in the bottom layer. The difference is thought to be due to the submerged sill.at Boca Grande.. On.the other hand, addition of wind creates significant particle displacements in both surface and bottom, though.in different directions. The model provides a possible clue to the breakdown of the stratification during the dry winter months, through a tilt of the inter'face due to barotropic wind response. Finally, new. evidence is found that the water entering from Canal del Dique,though. fresh, can dive under the Bay surface water due to its sediment load. 3 2. Introduction Located on the Caribbean coast of Colombia, S.A., the city of Cartagena and the neighboring bay plays an important role in that country's economy. During the Spanish colonization period remarkable ocean engineering projects were undertaken in an effort to protect the city of Cartagena from the attack of pirates. A submerged rock wall, over a mile long, was erected across the northern entrance to the Bay at Boca Grande, Fig. 2-1, to keep ships from entering. This wall is still in place and is an important hydrographic feature in that it limits the depth through which Bay water can exchange with the ocean to one or two meters. Inside the Bay, the water is quite deep 25-30 m except close to the shores. This characteristic along with good natural protection against large waves make the Bay an excellent harbor. The narrow inlet, Boca Chica, in the south is close to 20 m deep and serves as the navigation channel for ships entering and leaving the Port of Cartagena. Given these advantageous conditions it is not surprising that the Port has become one of the largest harbors of Columbia. A number of industrial plants that depend on the shipping facilities have developed along the east coast of the Bay. The shoreline to the north is heavily developed into residential, commercial and resort type communities. The remaining shoreline to the south and on Isla Tierra Bomba is relatively undeveloped with small villages only. Tha bay is approximately 14 km long and 6 km wide with an average depth of about 20 m, It is irregularly shaped and has several small 4 7z 0 r---------- qN- AGI All, Y 1 8 L A TIERRA BOMBA AP Ihl V" L 2762) 1-l. A.C-A.1 D- J7 C /Q C11'- H.:@. 1, o 116-1 Fig. 2.1. Cartagena Bay. Defense Mapping Agency Chart, COL261. Soundings in m. 5 embayments, the largest.of.which forms the inner harbor in the north. The Canal del Dique, which leads water from the river Magdalena in the northwest to the southeastern corner of the Bay was originally dug by the Spaniards to allow boats carrying treasure to reach Cartagena without venturing out into the Caribbean and the waiting pirates. This canal is now a significant source of freshwater and sediment which gives the Bay characteristics similar to those of an estuary. The extensive urbanization and industrial development have inflicted stresses on the Bay environment. Pollution from domestic and industrial waste is significant but to a large extent not quantified directly. One exception is mercury content3which was found to be at dangerously high levels at least in fishes during an earlier study, FAO/CCO 1978. In response to the need for better understanding of the present condition of the Bay and to train Colombian professionals in dealing with coastal and estuarine environmental problems the University of Miami with support from International Sea Grant joined together in a cooperative program with the Colombian agencies steered by the Colombian Oceanograhpic Commission (Comision Colombiano de Oceanografia, CCO), UM and CCO would work together in an interdisciplinary effort to carry out a baseline study of the physics, chemistry and biology of the Bay, with training of Colombian personnel being of primary concern. This report is one of the several resulting from this project and details the hydrodynamic aspects of the problem. The development of an understanding of the hydrodynamic transport and mixing is'an essential phase of-tbe overall effort to formulate a water quality model of the Bay. Such a model is an invaluable tool for developing an understanding of the underlying processes, for data inter- pretation, and for evaluating the-impact of management alternatives .for the.Bay and its adjacent waters. While the overall objective of this project is to determine the state of water quality in the Bay, the processes that affect it, and the rat es at which changes take place; the specific objective addressed here relates to the hydrodynamic forcing and response of the Bay. Particularly, -one would like to determine why, where and how fast a water particle moves (transport and mixing), and what the rate of exchange of water between-different areas is(flushing). .7 3. Technology Transfer As an important part of this project a series of lectures were given to introduce the concepts of coastal hydrodynamics applied to estuaries and bays. These formal lectures were presented in April 1979 to an audience of approximately 50 students of Colombian Universities and navy personnel. The lectures were supplemented by subsequent open discussions of the lecture material. Through active participation in field measurement exercises and data analysis, further practical training was given to the staff of CIOH (Centro de Investigaciones Oceanograficas e Hydrograficas). This training was amplified by informal lectures on numerical methods and modeling given extemporaneously throughout the duration of the project. A brief description of the above mentioned activities are now presented. 3.1 Short Course A total of 10 lectures were given in cooperation with the CIOH staff. The lectures presented the rationale for studying coastal hydrodynamics and a qualitative description of the commonly encountered phenomena such as, tides, wind driven currents, dispersion ,,stratification, data collection, data analysis and modeling. Additional lectures presented the background information on Cartagena Bay and previous work. As progress was made in the research activities subsequent informal lectures on data analysis, data interpretation, numerical analysis and modeling were presented. 8 Summaries in Spanish of the formal short course lectures will be ..given in a separate publication. 3.2 -Salinity Computation from Temperature and Conductivity The CI OH equipment for measuring water mass characteristics consists of a Kahlsico instrument which measures conductivity and temperaturefrom a probe.. Although it is possible to obtain the salinity by using appropriate graphs it is more efficient to computerize the conversion for large. quantities of data. Weyl (1964) derived this empirical formula log Ks = 0.57627 + 0,892 log Cq'(0/00) @ 10 -4 T 188.3 + 0,55 T + 0,0107 T 2 2 CP'(.Q/oo) (0.1-45 - 0.002 T + 0,002T (3.1) where K specific conductance in millimhos per cm s T 25 t t temperature in Celcius The chldrinity Ck is converted to salinity by the expression, (Cox 1965): S O/oo 1.8065 Ckotoo Equation (3,1).i.s rearranged. f(CZ) 8920 log CZ (0/oo) + AT C9, (0/oo) T[88.3 + 0.55 T + 0.0107 T 2 4 10 [log K 0.576271 0 (.3.2) s 9 where A = 0.145 - 0.002 T + 0.002 T2 This equation (3.2) is solved for Ck by using a Newton-Raphson iteration. The derivative of (3.2) is f'(CZ) = 8920 1 1 - + AT (3.3) ZnlO CZ(O/oo) The procedure for finding the chlorinity then consists of 1. Obtain initial estimate of Ck = K /3 2. Compute f(CX) from (3.2) 3. Compute f'(Ck) from (3.3) 4. Compute new estimate of chlorinity Ck = Ck f(Ck) fl(CO The iteration is restarted at step 2 until a sufficiently accurate estimate is achieved usually in less than 10 iterations. The listing of a FORTRAN program which carries out the above pro- cedure on any standard computer is presented in Appendix A. 3.3 Harmonic Analysis Although small in range the tides may play an important role in the circulation of Cartagena Bay due to their persistence. In order to pre- dict or hindcast the tides at a location, e.g. for the purpose of specifying boundary conditions for a model, it is necessary to have the appropriate tidal harmonic constants. The technique briefly reviewed here for obtaining the harmonic constants from a measured time series is described in more detail by Dronkers (1964). 10 Let the measured time series be given by . The predictor to be used is where is the sampling interval and are the astronomical tike periods for which the harmonic constants, and , are desired. The harmonic constants are determined using the least squares method such that is minimized. This is achieved when These equations are solved simultaneously for the A's and B's. The FORTRAN listing of a program that performs a least squares harmonic analysis is contained in Applendix B. 3.4 Modeling The use of models is essential for the analysis of circulation in a complicated water body such as Cartagena Bay. The models can be a significant aid in interpreting field measurements and are invaluable tools for predicting purposes. A set of numberical finite element models are available and could be adapted to the Bay. These include a vertically integrated hydro- dynamic model Wang (1978), a two layer 2-D vertically integrated hydro- dynamic model Wang (1975) and a 2-D vertically integrated dispersion model Leimkuhler et. al. (1975). The transfer of these models to the staff of CIOH was hampered by lack of a suitable computer at the Naval Academy and also disrupted by the transfer of personnel since the people with a background in oceanography usually are career officers, Nevertheless a number of informal lectures were presented to Tn. Medina, Tn. Urbano and Mr. Pagliardiniof CIOH. These lectures covered numerical techniques, mainly finite difference methods, and the formulation of hydrodynamic model equations. In September 1981 Tn. Medina spent one week in Miami learning to use the two-layer model for Cartagena Bay and to produce a user's manual. 12 4. Data Collection Information on a number of. parameters governing the flow or deline- ating the flow response in Cartagena Bay was collected. In order to include seasonal effects an attempt was made to carry out the*fie.ld work on a quarterly basis and.over a duration of 2 years so that the repeatability of observations also could be established. The first sampling period took place in June and July of 1979 and the last in May of 1981. After initial coordination and supervision the field effort was carried out by CIOH staff and copies of the.raw data transmitted to University of Miami for further analysis. ..4.1 Canal del Digue This man-made canal which connects the River Magdalena with Cartagena Bay plays several important roles in the water quality of the Bay. It is the major source of freshwater and probably.also of non-marine sediment to the Bay, Due to very shallow depth (1 to 2 m) at places only minimal boat. traffic takes place in the lower most reach of the canal, consideration is being given to deepen the canal for deeper draft vessels. The discharge in the canal is primarily governed by the rainfall -in the River Magdalena's catchment areas. The discharge rates for the years 1975-1978 as inferred from measured stages are shown in Fig. 4.1. It is estimated that approximately 1/5 of the flow at Incora reaches the Bay*- No records Are available after 1978. M3/s 1100 1000 900 800 700 FJ 600 500 400 300 200.. 100 J FM A Mi J ASO ND J F M AM J J AS ON D J F M A MJ J A S 0 ND'i F@i7M'7JIA SaO'N @ P- p i D 75 76 77 78 Figure4.1. Canal del Dique discharge at Incora, Km 7. 1975-78 14 Along with the canal fresh water a large amount of sediment is brought into the Bay. The transport rates vary with flow rate but may reach 3 close to.3000 kg/s during peak periods, About 22000 m /year of sediment enters the Bay as bed load and it is estimated that the total load is approximately 330000 m3/year. If all the sediment was spread evenly over the bottom this would roughly correspond to an accumulation of 4 mm/year. In reality an unknown quantity of sediment is probably exported from the Bay to the adjacent ocean. 4.2 Rainfall The average monthly rainfall measured over 31 years at Crespo airport, Cartagena and over 14 years at El Banco, Magdalena provins are shown.in Fig. 4.2. 4.3 Wind The winds in the areashow a distinct.seasonal p attern with a strong sustained wind out of the north during.winter and lighter more variable winds generally.out of the south-southwest the rest of the year. Some sea breeze effect is al'so noticeable. @4.4 Tides Tidal elevations were recorded at Isla Tierra Bomba near Boca Grande and at the.pilot house dock at Fort San Jose near Boca Chica, The tide gauges were Stevens Type F water level recorders. This gauge operates on the float system and records the elevations on a graph paper.. Attempts were made to measure.tidal elevations at the two stations ..simultaneously and over a month long duration. However, due to various cm/mth 40 El Banco (Magdalena) (14 years) 30 Ln 20 10 Crespo, Cartagena (31 years) J F M A M i J A S 0 N D Figure4.2. Average montbly rainfall I 16 malfunctions this was not possible. Useful data were obtained from the Boca Grande gauge for the period .09:00, July 22, 1980 to 21:00 August 19, 1980. The Boca Chica gauge produced data from 10:30 September 16, 1980 to 10:30 October 13, 1980. Figures 4.3 and'4.4 show plots of parts of the data. Unfortunately, no overlap was obtained during this period. Short periods of overlapping data were obtained during October 1980. The longest uninterrupted period is shown in Fig. 4.5. Attempts to obtain.tidal data from the Bay interior were unsuccessful because of difficulties with.gauge operation and servicing. The mean tide range in the Bay is about 20 cm, while the mean diurnal range is 33 cm. 4.5 Salinity-Temperdture-Depth Profile Profiles of conductivity salinity and temperature were measured against depthon a quarterly basis. A Beckman RS5-3 portable instrument and a Kahlsico instrument were used. Although, the Beckman is a far superior instrument which gives direct salinity readout the Kah1sico had to be used when the Beckman was unavailable. Due to the small tidal range-and motion it was found that profiles taken during'high water slack and low water slack were undistinguishable. Each sampling period covered the 12 stations shown in Fig. 4.6. The raw data are tabulated in Appendix C and plotted in Figs. 4.7ato 4.79. Due to lack of proper.callbration or instrument inaccuracy several OA- W 0.2- 0 6 0 1 2 4 7 0.4- w 0+- 9 10 11 12 1@ 14 1@ 1@ 17 1@ 0.4- W 0.2- 0-1 19 20 21 22 23 24 25 i7 TIME (DAYS) BOCA GRANDE Fig. 4.3. Boca Grande tides, record begins July 22, 1980 at 09:00 Hrs. 0.4- W 0.2- 0 0 2'. 3 4 5 7 8 9 .0.4- W 0.2- 01 10 12 1@ 14 15 16 17 18 0.4- W 0.2- C3 P 0- 18 19 20 21 22 23 24 25 26 27 TIME (DAYS) BOCA CHICA Fig. 4.4. Boca Chica tides. Record begins September 16, 1980 at 10:30 hrs. 0.6- OA- BOCA CHICA BOCA GRANDE 0.2- 01 0 24 48 72 96 TIME (HOURS) Fig. 4.5. Simultaneous tidal elevations at Boca Grande and Boca Chica. 20 CARTAGENA N 500 0 2000 M OOC@NDE ION 1AZZIM OM1 C@ VIKiMMOS ISLA TIERRA DOMOA 11L.TOWICADDRA @ @ BOCA ICA M2 CANAL DEL DIOUE Conductivity -Temperature -Salinity Profiles Salinity -Temperature -Velocity Profiles Tide Gage Station MI-M2 Recording Current Meter Station Fig. 4.6. Hydrographic sampling stations in Cartagena Bay 21 STATION 01 STATION 02 STATION 03 0800 0823 0900 SALINITY SALINITY SALINITY agog 3000 3000 REDO 10-00 3600 9200 8060 $600 Cl. 0 x is ilk. CL Q. (L w w w 0 ton victo gicto sioc, 36.00 29.00 Sao* 15.00 noo sa.00 TEMPERATURE TEMPERATURE TEMPERATURE STATION 04 STATION 05 STATION 06 0915 0945 1000 SALINITY SALINITY SALINITY 22.00 loop Woo 2200 $000 Hoo MG, soloo, 841.00 0- 0 is. xto CL w w w so sioc, &;.Do 26.00 Igloo .00 Woo tioa 3;.00 TEMPERATURE TEMPERATURE TEMPERATURE STATION 07 STATION 7A STATION 08 STATION 09 1020 1035 1103 1125 SALINITY SALINITY SALINITY SALINITY 1200 30.00 3600 2100 $600 stoo its 00 so 00 as Do 2200 3000 4*00 0 0- x xis. Xis- x is a. a. CL w w ui -0 so. of 00 tDoo 33@0 as-00 **.Do 3&.00 2000 29.00 33.00 as*oo [email protected] 33.00 TEMPERATURE TEMPERATURE TEMPERATURE TEMPERATURE STATION 10 STATION 11 STATION 12 1145 1200 1220 SALINITY SALINITY SALINITY froo 3000 541,00 2200 8000 3*00 12.00 ".Go go 00 0 xIs. Is CL CL w a so fico fv@,00 a go 9$00 2900 25.00 81,00 ticioa00 TEMPERATURE TEMPERATURE TEMPERATURE Fig. 4.7a. Salinity-temperature graphs. June 21, 1979 22 STATION 01 STATION 02 STATION 03 0900 0910 0929 SALINITY SALINITY SALINITY 2200 3000 sea* 2200 1000 as** 1200 1000 $too 0. 0 0 X CL IL tL w w so 20. ts.00 B5,00 tioo *1@00 39.00 24.00 to'60 zi.00 2 00 TEMPERATURE. TEMPERATURE TEMPERATURE STATION 04 STATION 05 STATION 06 0944 1002 1013 SALINITY SALINITY SALINITY Uob 2200 5000 $400 2800 40.00 56.00 a. 0 is w w so so go, 16:00 2@00 "Do- SO 00 19.00 13.00 29.00 2;00 23,06 TEMPERATURE TEMPERATURE TEMPERATURE, STATION 07 STATION 08 STATION 09 STATION 1032 1050 1108 SALINITY SALINITY SALINITY SALINITY 2200 Hoo $Goo 1200 Bobo ago* 1200 *000 3800 at 00 80106 $too 0. 0- 0. 0. It. Is. x is. CL CL 0. w w w w 0 0 a 0 so 2- .01.0 .100 06 21;'OD 15.00 0500 t;.00 53.00 a$" me." S;.60 TEMPERATURE TEMPERATURE TEMPERATURE TEMPERATURE STATION 10 STATION 11 STATION 12 1125 1139 1145 SALINITY SALINITY SALINITY et 00 3000 Be C* 2200 so wbe 00 11200 50100 34.00 0. 0- 0 XG. CL CL w Uj 0 so so to 00 to 00 3300 1500 2@0. 1 00 2600 goo* 8;.90 TEMPERATURE TEMPERATURE TEMPERATURE Fig. 4.7b. Salinity-temperature graphs. October 16, 1979. DEPTH (M) F4 Cd lp0 0 DEPTH (M) C z DEPTH (M) 14 G z 0 a 0. Ic DEPTH (M) 8 DEPTH (M) z DEPTH I M) 0 a 0 co rt -4 rn 0 9 9 In V m m m DEPTH (M) 8 LE 0 pt s 4 cu -C rt x M 0 m tl 0 M 0 DEPTH (M) z DEPTH (M) m OQ 3@ 00 M 0 40 5 -4 P4 mic r A c z DEPTH W 00 9 10 OD 24 STA TION 01 STATION.02 STATION 03 0859 0911 0925 SALINITY SALINITY SALINITY a 030.00 56.00 MOO MOO 10.00 39.00 t 0 0- 0, Is- 15- Is CL IL a. w w 0 30 30-r- 3500 26.00 to.00 t 26.00 53.00 MOO to 00 TEMPERATURE TEMPERATURE, TEMPERATURE STATION 04 STATION 05 STATION 06 0940 0957 1009 SALINITY SALINITY SALINITY 2200 30,00 3800 to 050.00 39.00 so.00 so 100 Be 00 @x Is- X15 =16 0 0 IL IL w w so so- 5,00 240 58.00 15.00 19.00 ".00 atca to.00 33.00 TEMPERATURE TEMPERATURE TEMPERATURE STATION 09 STATION 07 STATION 08 1019 1030 1044 SALINITY SALINITY SALINITY it 00 Up 54i0o at 0 $0.80 114.00 22.00 30.00 3800 0_7 X15- x X Is. I Is. 0. (L CL w w w 0 so 0 30 a 11960 33.00 '25'.00 33,00 ts.00 ttoo 5.00 TEMPERATURE TEMPERATURE TEMPERATURE STATION 10 STATION 11 STATION 12 1056 1111 112T S@ALINITY SALINITY SALINITY 22.00 30.00 36.00 2200 30.00 MOO 22.00 30.00 38.00 0 a S is is Is. IL w CL w w so so so .5.00 19.00 3s.00 2500 ttbo 3300 tooo 99.00 3 .00 TEMPERATURE TEMPERATURE TEMPERATURE Fig. 4.7d. Salinity-temperature graph Is, October 28, 1980. .0 .25 STATION 01 STATION 02 STATION 03 1410 1420 1431 SALINITY SALINITY SALINITY 1111.00 30.00 30,00 22.00 10.00 36.00 R1.00 10.00 3640 0. 0- 0. OX to- x is- x is- CL CL IL w w w $01 Sol, $01 Ii.90 26'.00 53'.00 Ii.00 aoo $3.00 to!00 10'.00 S"o TEMPERATURE TEMPERATURE TEMPERATURE STATION 04 STATION 05 STATION 06 1438 1450 1500 SALINITY SALINITY SALINITY 28.00 3Q00 119.00 22.00 30.00 54.00 22.00 90.00 IS-09 0. 0-. 0- x If- is- X I$- I w CL L CL w us 0 ti@oo 29"00 115,00 111.00 10.00 33.00 15.00 otoo $3.00 TEMPERATURE TEMPERATURE TEMPERATURE STATION 07 STATION 08 STATION 09 1512 1525 1540 SALINITY SALINITY SALINITY 92.00 40.00 "Ac Sam 20.00 46.00 21,00 10.00. 08.00 0- 0. Is- to- Be- IL w w 0 Sol so 301 25@00 19.00 1111.06 ROOD 29"..00 33.00 25,100 Ii.00 SS@Do TEMPERATURE TEMPERATURE TEMPERATURE STATION 10 STATION 11 STATION 12 1555 1608 1620 SALINITY SALINITY SALINITY 22.00 30-00 Woo 11.00 110.00 116.00 22.00 30.00 3111100 0- 0- 15- X to. to- CL tL w w 101 Sol. 801 21,00 20.00 43.00 26.00 10.00 33.00 13,00 29.00 53.00 TEMPERATURE TEMPERATURE TEMPERATURE Fig. 4.7e. Salinity-temperature graphs. October 28, 1980. 26 STATION 01 STATION 02 STATION 03 1424 1435 1450 SALINITY SALINITY SALINITY 22.00 $000 341,00 noo 1000 5900 22.00 50.00 36.00 0. 0- 0- X to- x is- XIs- CL IL LU w w so 30- ..00 2900 83.00 go.00 2900 13.00 2500 29,00 3300 TEMPERATURE TEMPERATURE TEMPERATURE STATION 04 STATION 05 STATION 06 1500 1515 1524 SALINITY SALINITY SALINITY 22LOO 3000 3800 at 00 3000 30,00 2200 soloo Bass 0- 0- 0- X Is- x W X Is- 9L IL LLJ w so 30 so 2500 1900 $300 noo 2900 3 .00 25.00 29'.00 53.00 TEMPERATURE TEMPERATURE TEMPERATURE STATION 07 STATION 08 STATION 09 1531 1540 1550 SALINITY SALINITY SALINITY 1200 30.00 110,00 22.00 3000 3000 2200 30.00 316.00 0- 0. 0- xIS- X Is- CL 4L w w w 30 30 1 so 2500 21100 33.00 15.00 2900 3300 22.00 29.00 3300 TEMPERATURE TEMPERATURE. TEMPERATURE STATION 10 STATION 11 STATION 12 1600 1609 1618 SALINITY SALINITY SALINITY 22.00 Moo 5000 22.00 30.00 asoo 22.00 30.00 36.00 0- 0. 0- is- xis- Is- F- CL IL IL w w w 0 301 __`1 30 so 2600 2600 33.00 2500 2900 3 .00 25.90 2900 33.00 TEMPERATURE TEMPERATURE TEMPERATURE Fig. 4.7f. Salinity-temperature graphs. February 9, 1981. 27 STATION 17 STATION 08 STATION 07 1225 1235 1250 SALINITY SALINITY SALINITY 22.00 3000 30.00 22.00 $0.00 50.00 24.00 3000 8&00 0 0- 0- 15. is- 1B_ w w to 101 $a[ eizo [email protected] 381.00 twoo [email protected] 3 1.00 45.00 Ito* 53.00 TEMPERATURE TEMPERATURE TEMPERATURE STATION 13 STATION 14 STATION 15 1311 1320 1259 SALINITY SALINITY SALINITY 22.00 5000 ".00 21.00 50.00 16.00 29.00 8000 $0,00 0- 0- a- x is. w w Ii.00 2@00 s '00 tioo fioo 4 .00 ti.00 to'.** 83.00 TEMPERATURE TEMPERATURE TEMPERATURE STATION 16 1211 SALINITY 12.00 30.00 moo J w to:00 Riao 33.00 TEMPERATURE Fig. 4.7g. Salinity-temperature graphs. February 10, 1981. 28 readings of salinity were 377. or above. Since laboratory analysis of water samples taken for the chemical analysis did not show'such hi:gh value the plotted data are corrected to yield similar maximum salinity values. The correction was made by making the maximum salinity in a pro- file equal to the maximum value found in the laboratory and subtracting the difference from each of the values in that profile. The absolute value for salinity in a profile.is therefore subject to some inaccuracy, however the relative variation of values within the profile should be reasonably accurate. 4.6 Drogues A number of drogue studies were carried out in June and July 1979. One study consisted of the deployment and tracking of three drogues placed at different depths. The drogue.s were made by joining two square pieces of,plywood at a right angle to form a cross. Weighted and tied with a string to a surface buoy the drogue is assumed to follow the path of the .surrounding water particles. Tracking of the drogues was accomplished by shooting sextant angle from a boat to fix points on land. The observed drogue paths are shown in Fig. 4.8. Since considerable inaccuracy is inherent in this positioning system the relative drogue motion is more significant than the absolute motion. The'wind during the measurements is listed in Table 4.1. The drogue experiments were.carried out under the charge of Ricardo Parra Suarez of CIOH. 29 CARTAGENA N wo 0 BOCA GRANDE ION ,;@ 114F, MMOO. ISLA TIERRA 9014111A 4 lp CLAICTRWICADORA BOCA *SURFACE BUOY - 8 motors BUOY o IS meters BUOY CANAL DEL DIOUE Fig. 4.8. Observed drogue paths. 30 Wind Wind Date Time Direction Speed km/hr Date Time Direction Sp'e-ed km/hi June 0900 SW 5 July 09:00 Calm 22 10:20 Sw 7.5 3 10:00 W 3 11:15 SW 6. 10:30 S 3 14:10 Sw 8 11:00 Calm 15:0.6 $W 9 12:30 Sw 7 15:33 NW 8 12:45 NW 3 NW 10 13:00 NW 10 15:00 Calm 21 10:00 Calm 11:05 Sw 10 12:10 SW 10 4 11:07 Sw 10 Sw 12 12:42 Sw 5 .14:45 Calm 15:53 N 10 25 10:30 Calm 10:55 Calm 12:00 Calm 13:20 NW 10 14:15 NW 10 15:35 NW 10 26 09:20 Calm 10:00 Calm 11:00 St 3 11:45 Calm 12:00 NW .8 14:35 NW 10 28 11:15 W 7 13:45 W 7 15-:00 W 6 15:20 W 6 Table 4.1. Wind speed and direction during drogue experiments. 31 4.7 Currents Current velocities were measured at a number of locations shown in Fig. 4.6. Two modes of operation were employed. One consisted of using a portable electromagnetic current meter (Marsh-McBirney) from an anchored boat. The direct read out feature of this system is an advantage. Also, the ability to carry out vertical profiling and to choose sampling stations irrespective of ship traffic is of importance. The major drawback of using this mode of operation are the relatively short continuous sampling periods and the susceptibility to interference by surface gravity waves that rock the boat. This latter effect, in fact, made it impossible to obtain good data at Boca Grande since waves always seem to be significantly present there. Figure 4.9 shows the measured velocities at Boca Chica, D of Fig. 4.6, and Fig. 4.10 shows velocities near Cano de Loro, C of Fig. 4.6. In a second mode of operation a moored recording current meter was used to obtain a longer time record less subjected to interference from surface waves. The current meter used is a Sea Trak Savonius rotor in- strument produced by Hydroproducts. It was installed in the narrowest section of the Bay in front of Punta Arenas using a taut mooring system with a subsurface buoy, see Fig. 4.6. The meter was first placed at approximately 20 m below MSL for 14 days, then moved to 4 m below surface for another 28 days and finally back down to 26 m. During this latter installation an Inter-Ocean current meter was placed simultaneously at 4 m. Unfortunately, the Inter-Ocean system never recorded any useful data. N 0630 N 0700 1139 1430 0900 0930 1300 1130 1400 0800 0900 12oo 1330 1400 1-230 1330 1-500 9m COP 3 m 500 10 .15 cm/s a Velocities in time at fixed depth 2 2 0 7* 13 13 9 5 4 0800 4 1200 2 3 b. Velocities in vertical at fixed time 9 :UU@ @O9 3 O@ 1200 1 1 330 9 _ @4@ _@80. @1200 FIG. 4.9. Velocity plots (hydrographs) at Boca Chica. October 18, 1979. 33 14:00 13:30 0. 7:26 0 14:30 151,50 8-00 8:30 SURFACE 15:30 14:30 B-00 6:30 13-00 7:26 15:00 8:30 3m 9:00 6:30 15-30 16:00 6:30 15:00 13-00.*- 0 20 m 14:00 9:oo 13,30 8:00 7:26 CANO DEL LORO OCT. 209 1979 14*00 .0 7:26 r 15'3 8.0 @830 160/0 a 30 14:0@0 @9- 00 Fig. 4.10. Measured Velocities. 34 In the first deployment at 20 m depth, the Sea Trak current meter malfunctioned and no velocities wererecorded., However, the following deployments were apparently more successful providing more than 20 days of dat4 at 4 m depth starting June 4, 1981, Fig. 4.11, 15 days of data at 20m depth starting July 8, 1981, Fig. 4.12 and about 2 days of data at 20 m depth near Boca Chica starting July 23, 1981. At Boca Chica the current meter stopped working on the third day. The conductivity and pressure monitoring sy�tems.were malfunctioning during all the observations. It was intended that during the deployment of the recording meter weekly profiles would be taken with the portable current meter and S.T.D. meter in order to compare the measurements and to develop a-picture of the verticalstructure. These profiles were not made. 4.8 Turbidity The turbidity of water samples collected at approximately 40 chemistry stations were-determined using a laboratory nephelometer made by Hach. The measurements were-carried out for July and October 1980, and January and May 1981. The results obtained from surface and-bottom samples are shown in Figs. 4.13 a-h. The measurements were done mainly to provide a qualitative picture of the turbidity distribution.and possible sink.or source areas.. Hence, no:attempts were made to relate turbidity units with actual contents of solids. N 10 CM/S Velocity N-S Component 5 0 6 12 Is 24 3d 36 42 48 hours -5 S w 10 CM/S 5 0 V4 VUV 12 V 'S .0 36 48 hours -5L E Velocity E-W Component Fig. 4.11. Measured velocities at Punta Arenas. June 1981. U 1@ k4l N 5 cm/s A 0 1 V v IV I v v -5 - Velocity N-S Component S W 5 cm/s A 0 IV I IV I I -5 L E Velocity E-W Component 2Ft 0- 0 6 12 18 24 30 36 42 48 hours Tide Fig. 4.12. Measured velocities,at Punta Arenas. 20 m below surface. July 1981. The predicted tide at Cartagena is also shown. 37 CARTAGENA SURFACE TURBIDITY (JTU) N July 1980 Md 1.9 SOD 0 xWon 1:7 MOCA GRANDE ION 1:2 1:4 2:6 3.6 1.6 4:2 .7 3:2 2:0 Discharge VIRING011 from TIKMA mom" Vikingos 3:2 7.7 1; 5:3 1ELMYRIMADORA 2.9 80CA 2:2 3:0 3:6 2:3 2:3 2.0 3:0 2:2 2:0 2:3 2.6 ..4:2 3:6 3:4 CANAL DEL MQUE 4.6 6.5 Fig-4.13a. Observed Turbidities 38 CARTAGENA BOTTOM TURBIDITY (JTU) 3 N July 1980 0.8 1.6 0 2=M 5:2 BOCA GRANDE ION 0:9 1:3 1:8 4.4 1:3 'ft:tm 2: 4 3:4 6:6 2:2 C@ VWjNoOS MA TIERRA 9"A 3.2 2:6 1:2 V LW-T10`ICAD,*A 4.2 0.6 3. BOCA ICA 0:5 1.: 8 2.9 1.2 1:7 0: 7 1: 9 2; 5.0 1:3 1:1 2.1 CANAL DEL DIOUE 3:0 6 Fig. 4.13b. observed Turbidities 39 CARTAGENA SURFACE TURBIDITY (JTU) OCT. 80 .38 N f .58 .55 500 0 .38 '1'4t "AI12 .41 .37 to" .35 .30 *--_z .24 .42 .4 .24 .78 1.62 -13@14 _.am ISLA TIERRA Ill"A 9 ..39 1.08 1.86 ELIETWOrADORA NOCA ICA 1.62 .55 .41 .28 .78 1.44 .17 31 4.35 2.10 4.38 .78 2.07 .38 159.0 .60 12 8-mAL DEL DIME .90 .90 Fig. 4.13c. Observed Turbidities, 40 CARTAGENA BOTTOM TURBIDITY PTU) OCT. 80 .17 N 15.0 500 o 2000 on .20 BOCA GRANDE .18 .17 ION .24 .22 *.30 .16 qftr--4 .15 .3 5.70 d= .28 .18 .24 VWNWS JUA TIERM SOMMA 9 .31 .43 07 ELECTRWCADORA BOCA .15 .21 97.80 .22 f> 19 .08 .17 .38 .84 .42 .16 .39 .30 CANA& DEL DIOUE 2.7 .34 Fig. 4.13d. Observed Turbidities. 41 CAltr"CMA SURFACE TURBIDITY (JTU) January 26-30, 1931 N 4.5 5. wo o 3.7 BOCA 61JAmot 5.5 6.8 6. 2. 5.5 VWASM ISLA 7?ER*A mom" 3.5 3.7 5.9 2.1 tucToorrAvom 6,5 BOCA $CA 1.3 2.8 1.7 5.3 3. 3. 5.8 76. 3,6 3.8 CAN" DEL DIME 5.5 3.6 Fig. 4.13e. Observed Turbidities. 42 CARTAGENA BOTT911 TUrBIDITY (JTIJ) January 26-30, 1981 N 7. 4.5 500 0 2000m BOCA GRANDE 2.7 2.5 ]ON 31. 7.1 p 7.7 2.8 4.2 5.8 3. ISLA TIERRA sommA 4.5 9 95. 6. 5.2 ELECTRWICADDRA BOCA ICA 2.4 2.8 2.3 1.9 2.2 2.5 2.5 3.3 8.1 66. 3.1 5.2 6.3 CANAL DEL DIOUE Fig. 4.13f. Observed Turbidities. 43 CARTAGENA SURFACE TURBIDITY (JTU) May 4-8, 1981 5. 5.4 N f 4,1 Zino 3.0 3.8 80CA GRANDE 1.6 3.5 ION 2.2 3.1 izp,019. 1.5 "-%V* 3.3 4.3 3.7 6.8 5.5 4,2 1@@ VWAPOWS MA nvutA MOKM 3.8 3.6 5.4 5.3 ELS:TftvrAOWA 5.4 **CA 6.6 4.2 7.7 3.2 9.9 3.8 4, 3.6 5.8 21. 4.4 430. 4, 4.2 83. CANAL DZL. 370. Diout 2.1 3.5 Fig. 4,13g. Observed Turbidities. 44 BOTTOM TURBIDITY (JTU) may 4-8, 1981 N t ..3 2.5 1.5 wo 0 OOCA GRANVE 1,7 2.3 1004 1.3 2.2 w 2.9 4.6 2.6 7.3 2.4 ISLA YlEx4A 00146A 3. 6.0 VwAlmos 5. ELWTWSCADOPA @7 7.5 3.1 BOCA )CA 2.8 4. 4.0 2. 15. 2.2 1.2 55. 3.3 3.3 4X 4.2 4.1 5.3 OE(. Fig. 4.13h. Observed Turbidities. 45 5. Analysis of Data The most striking feature of the data which is of importance to the hydrodynamics of Cartagena Bay must be attributed to the vertical stratification. The exclusive cause of the stratification is due to the Canal del Dique inflow since other runoff and sewage disposal (about 1.2 m3/sec) are comparably small. Since stratification is a function of freshwater inflow and energy available for mixing, mainly from tides, it is useful to compare the freshwater inflow volume during a tidal cycle with the tidal prism. A typical inflow rate from Canal del Dique is QF = 100 m 3Is during the wet season. During one tidal cycle corresponding to 45000 sec this translates 6 3 into a volume of VF = 4.5 10 m . The tidal prism, which is the volume of water entering the bay from the ocean during flood, can be approxi- mately determined if the bay surface area and tidal harmonic constants are known. The surface area of the Bay is meagured as 82.6 - 10 6 m2. Because of the relatively small size of the gay-compared to the tidal wave length, the water surface inside the Bay can with good approximation be assumed horizontal. Then, the tidal prism is simply the surface area 6 6 3 multiplied by the tidal range, P = A.H = 82.6 10 . 0.2 = 16.5 - 10 m Since P is only 4 times VF it is clear that the water in the Bay will be strongly stratified. Of course there are other times of the year when VF is very small and we would then expect to have a partially stratified or well-mixed situation. This qualitative analysis is well borne out by the measurements of salinity and temperature. 46 The effect of the stratification is clearly observed in the plot of drogue tracks, Fig. 4,8 which shows that the velocity in the surface layer is quite different from the velocity near bottom in both direction and magnitude. A stably stratified water body requires energy to mix it up, other- wize it tends to reduce mixing compared to homogeneous water. This is of particular importance for Cartagena Bay which only has one narrow opening, Boca Chica deep enough to effect exchange with the ocean, while Boca Grande is only 1.5 to 2 m deep. It is therefore expected that the deeper denser layer of water in the Bay will exchange only very slowly. Some reprieve is obtained during winter months, the dry and windy season, when vertical mixing can take place. Based on the measured salinity-temperature profiles, the Bay may be considered as a first approximation as a two layer system. The -surface layer contains a significant amount of freshwater and has an increasing salinity with increasing depth below surface. At a certain depth the salinity becomes almost constant and this portion is denoted the bottom layer. It is apparent that the thickness and characteristics of the surface depend strongly on the Canal del Dique inflows. However, attempts to correlate these parameters failed because it was impossible to obtain the canal flow data from HIMAT, (Instituto Colombiano de Hidrologia, Meteorologia y Adecuacion de Tierras) for the period of our field work. The discharge rates for previous years shown in Fig. 4.1 are highly variable and do not allow a reasonable extrapolation to be made. The ST 47 profiles seem to show a typical surface layer depth of about 8 m, which is fairly constant throughout the Bay. A rough estimate of flushing time for the top layer can be made using an average freshwater inflow rate and the volume of freshwater in the Bay. Flushing time is here defined as an average time for ex- changing all the water particles inside the Bay with ocean water. A reasonable average salinity value for the surface layer is taken as 31 ppt. Assuming the ambient ocean salinity to be 36 ppt the volume of freshwater in the Bay 36-31 VF 36 , VT where VT is the total volume of the top layer, 6 6 3 VT 82,6 - 10 . 8 = 661.- 10 m ThenVF = 92 106 m3 and the flushing time T = V F/ QF = 920000 sec = 11 days, The flushing time in the bottom layer cannot be estimated in this manner and a guess can only be made that under stratified conditions the bottom layer exchanges very slowly, on the order of months. The interior current meter measurements were to be used for more quantitative estimates of exchange rates and for verifying a numerical model, A detailed analysis of the current meter data might provide more quantitative estimates of long term residual currents. However, a complete digitization of the data is a tremendous job iqhich is beyond the scope of 48 of this project. only short periods have been plotted for analysis and model verification. Figure 4.11 shows the N-S and E-W current components measured 4 m below surface over two days at Punta Arenas, station Ml. A mixed tide is apparently discernible although other signals are quite strong in the N-S current. A typical tidal velocity amplitude in this direction is 6 cm/s. In the E-W component the tidal signal is very weak, however this is in a direction perpendicular to shore and therefore not surprising. Figure 4.12 shows the N-S and E-W current components measured 20 m below surface at Punta Arenas. Little visual correlation can be found between the velocities and the tide also shown in the Fig.4.17.. The large amplitude non-tidal current oscillatiorsare possible due to meteorologically forced surges and internal waves. The time scale of these fluctuations is 2-3 hrs. An estimate of the period of an internal seiche can be obtained assuming the speed of the internal wave to be c = Ap_ H 1H2 . H and P 6 (H 1+H 2) 1 H are the bottom and surface layer depths respectively. In our case we 2 may take H, = 20 m and H2 = 8 m. The density difference between the two layers is primarily governed by the salinity difference which we take as 3 36.5 - 31.0 = 5.5 ppt resulting in Ap = 4.5 kg/m . With the characteristic values we obtain c .5 m/s. As characteristic dimensions for the Bay we choose the length L 14000 m and the width of Punta Arenas W = 2500 m. The corresponding seiche periods are T, = 15.6 hrs and 2.8 hrs. When a complete analysis of the current meter recordings is made, the importance of internal seiches will be better understood. 49 Turbidity data were collected in order to identify source areas and possibly to develop a qualitative idea of water motion and mixing characteristics. The Canal del Dique discharge is a large known source of suspended solids. At times, an extensive turbid plume can be observed on the surface in the southern part of the Bay. At other times, a very small turbid zone exists with an extremely sharp boundary to the ambient water, This has led us to believe that suspended solids occasionally make the canal discharge heavy enough to make it sink, Whether it actually becomes a dense bottom current or it spreads out at some depth below surface cannot be determined from the sparse data available. When sufficient sediment has settled down the plume would become lighter and start rising. In fact "pockets" of lower salinity water have been found at the surface within 2 to 3 km northeast of the canal mouth, which supports this theory. A much more detailed study, than possible in this project, of this particular. problem could yield valuable information on the dynamic interaction between the canal discharge and the bay water. This information, in turn, could lead to a better understanding of the ecological impact of the canal and its effect on the general stratification of the Bay. The recorded bottom and surface turbidities show a rapid decrease in turbidity away from the Canal del Dique. Two other source areas appear to be located on the east coast of the Bay and the Boca Grande area, No clear picture can be discerned from the data, possibly due to the fact that the water samples for each chemistry cruise were collected over a total period of 4-5 days. To be useful as a tracer, turbidity would probably have to be sampled daily over a period of 10-20 days. 50 Finally, the hypothesis that at times the Canal del Dique discharge may actually sink below the surface due to its suspended solid load has been made and partially substantiated withturbidity and salinity measure- ments. This phenomenon and the correlation between freshwater discharge and Bay stratification characteristics are interesting and important problems warranting further investigation. The data collected as part of this project should be useful as a basis for comparison in future studies and to evaluate long term changes in the Bay. In summary, the field data show that the inflow from Canal del Dique causes the Bay to stratify into a two-layer type situation. Under these conditions, which can be expected to persist from March-April to November- December every year the water exchange rate in the surface layer is en- hanced due to baroclinic circulation and a reasonable flushing time estimate is 11 days. During this period very little exchange takes place in the bottom, which is estimated to have a flushing time of the order of months. In the winter months the Bay destratifies and although the flushing time may be greater than 11 days because of lack of density currents the well-mixed conditions allow significant vertical mixing to take place. The strong northerly winds during this period can provide the necessary energy input to effect mixing and to generate horizontal advection. 51 6. Model Formulation Cartagena is one of the most important Colombian sea ports. The city itself has an interesting history going back to the initial colonization of the Spaniards, and is a popular seaside resort that attracts tourists from many places. A very diverse industry, taking advantage of the excellent port facilities, has also grown out especially along the eastern shoreline of the Bay. It is apparent that both tourist and other industries will expand considerably in the future and that the impact of future developments on the water quality in Cartagena Bay need to be considered in the regional plans. The present investigation is partially addressed towards this problem and one of the objectives is to develop a model that can describe the existing processes in the Bay as well as evaluate the effect of various changes in the controlling input parameters. In 1974 Schaus developed a vertically averaged finite difference model of the Bay and considered the effect on circulation from various hypo- thetical modifications to the physical boundaries of the Bay. In view of our present knowledge with regard to the stratification of the Bay the work of Schaus is of little value in describing the actual dynamics of the water motion in the Bay. A model describing the dynamics of a two layered water body has been developed by Wang and Connor (1975). This model is a reasonable approxi- mation when a water body consists of two layers of fairly uniform but different densities. Although the surface layer in Cartagena Bay is not very uniform in density a two layer model may provide a first approximation 52 explaining the salient features of the stratified flow problem, The velocity profiles taken at Boca Chica seem to indicate a twolayer structure while other profiles show more of a continuous shear dis- tribution. These current measurements are subject to considerable uncertainty, as previously mentioned, because of wave action. The model is based on the equations of motions integrated vertically within each layer. The interface is assumed to be a material surface through which momentum can be transferred and across which the pressure is continuous. Any exchange of mass between layers must be parameterized externally. Since vertical accelerations can be expected to be negligible compared with gravity, the hydrostatic approximation is also introduced. Finally the Boussinesq approximation Is applied so that density variations are only included when multiplied by gravity. The equations then become forlayer 1, (bottom): for layer 2, (top): 53 q2x,t + q(qU2 q2x) Px + (u2q2y) ly @ fq 2y - (F 2p - F2xxq),x q1 + F 2yx,y + -@:-2q4T 2x - Tlx + qP2qn2,x qPlqnl,xq) 2 q2y,t + q(v2 q2xq),x + (qv 2q2yq)"qY fq 2x + F2xy,x (F 2p -F2yy) I'qy + 0qLq@T 2y - Tqly + qp2qn2,y - qplqnl,y qP2 where, see also Fig. 6.1 H = layer thickness qqx9qq qy = discharge in x and y directions U'qv = x and y velocities f = Coriolis parameter = 2 qQ sin = radian frequency of earth rotation = latitude F XqXI-F qYXFqyqy = internal stresses qP = pressure T T = x and y shear stresses qp = pressure TqI = surface elevation a comma denotes partial differentiation with respect to the following subscript(s) and the specific pressure force measures are 0q1 2 4q1 Ap0q, 2 4q1 F + gH +6q- 4q- H + 7q--P H 8qlp 2q1 220q9 Plo 8q1 P8ql4qo 8q1 8q1 54 q2y z 912 q-zx H2 H1 FIG. 6.1. Definition Sketch for Twolayer Model 55 The surface stress due to wind is determined from 2 T2 = Pair CD 10 where U 10 is the wind speed 10 m above the surface. The drag coefficient CD can be calculated from the empirical formula CD =(1.1 + 0.0536 - U10 ) - 10-3U10 in m/s Finally the internal stress terms which arise due to averaging over turbulent time scales and the vertical integration are parameterized using an eddy viscosity formulation. aq., 3q F E ( 3 + -@x1 1,2 xixy ij ax1 1 .3 with subscripts denoting x (1) and y(2) direction. The boundary condition for the problem consist of specified flow perpendicular to the boundary or surface elevations. The complexity of the equations require a numerical technique in order to obtain a solution. The finite element method has been chosen here because it allows conformity with a complicated geometry using relatively few grid points. 56 1 2 1 AP2 2 1 F2p gH2 + -f g P20 H2+P20 p2H 2 The pressures at the interface and bottom are P, = P2 + P20gH 2 PO = P2 + P 209H2 + plOgHl Bottom shear stress is parameterized as T qly Ox C (q 2 + q 2 1/2 Plo f lx ly H12 2 2 1/2 q Toy C (qlx + q 2il Plo f ly H12 where the friction coefficient is taken as the standard Darcy Weisbach factor multiplied by 8. The interfacial shear stresses are related to the square of the velocity difference of the two layers Tlx 2 2 1/2 _- = C fu u + (v v u Plo 1 1 2 1 2 2 1 T C {(u 2+ (v 21 1/2 (V T10 1 1 2 1 2 2 1 where C 1 is an interfacial shear stress coefficient. The magnitude of C is not well-known except that it depends on the density difference between layers and that its order of magnitude is close to that of Cf* 57 7. Model Adaptation to Cartagena Bay The main model modifications, compared to earlier applications in Massachusetts Bay, consist of incorporating the capability of using different boundary conditions in top and bottom layers and the possibility of excluding elements in the bottom layer grid where the total water depth is so small that a dense bottom does not exist. The first change is necessary to treat the Boca Grande entrance properly, since here the top layer has free exchange with the ocean while the bottom layer essentially is bounded by land in the form of a sub- merged plateau. The second modification allows a better approximation of the actual bathymetry and especially the shallow water near the edges of the Bay. The finite element grids consisting of linear trianglesfor top and bottom layers are shown in Fig . 7-1 . The intiial depth of the surface layer is taken as 6 m throughout. Although the real depth at Boca Grande is only a few meters, the depth of the top layer in the model is controlled by the interface position. The error incurred thereby should be small since the velocities in this area are fairly small, The effect of the submerged barrier is approxi- mately simulated by using an increased friction factor of 0.0035 and 0.0030 in the row of elements closest to the toundary. In the remaining area a constant friction factor of 0.0025 which approximately corresponds to a Manning coefficient of 0,025 in 17 m of water is used. 58 48 Is 43 4 as 2 2 0 6 12 24 Bottom Layer 6 38 55 5 IT 6 94 1 4 2 4 8 20 56 2 7 7"- 54 19". 71 24 55 V TO Surface Layer Fig. 7.1. Finite element grids for Cartagena Bay. 59 The Canal del Dique discharge is accommodated as a point source of strength 75 m3Is located at the mouth of the Canal. The finite element grid employed consists of 101 elements and 71 nodes with an average node distance of between 700 to 1000 m. The grid is a com- promise between a desire to resolve all important bathymetric or geometric features and efficiency of computation. The time step used for the com- putations is 50 sec while the courant condition using a distance of 1000 and � depth of 28 m is 1000/vr9-.81-28 = 60 sec. Computation of one time step on � UNIVAC 1100 system takes approximately 1.5 sec CPU and 40 K words of memory. 60 8. Model Applications Three model simulations are executed of the typical forcing con- ditions in order to compare with field data and to determine transport characteristics for situations where data are not available. 8.1 Tidal Flow The most consistent forcing of the Bay is provided by the astro- nomical tides. In order to simulate tidal currents appropriate boundary conditions must be prescribed. A mean tidal amplitude of 0.12 m is applied to the surface of the open boundaries. The tidal curve is assumed to be a sinusoid with a period of 45000 sec. Since the measured tides do not provide enough resolution to determine whether phase lags less than about 30 min exist two tests are made in the model. In the first run it is assumed that the tides at Boca Grande and Boca Chica are in perfect phase. For the second run Boca Chica is assumed to lag behind Boca Grande by 30 min. The results are only moderately sensitive to such variations and all the runs described in this report incorporate the 30 min lag. Similarly, a constant discharge of 75 m3Is is included as a simple source at the location of the mouth of Canal del Dique in all the simulated runs. The boundary conditions in the bottom layer consist of prescribed normal flow equal to zero at Boca Grande and a sinusoidally oscillating interface at Boca Chica. The amplitude for this oscillation is arrived at by scaling the surface amplitude by the relative depth equal to bottom 61 layer depth divided by total depth or 9/15 - 0.12 = 0.07 m. The inter- face is assumed in perfect phase with the surface at this locations. The model is stated from "cold", i.e. horizontal surface and inter- face with zero velocity everywhere, and allowed to dissipate this initial condition during the first 18000 sec. The result of the tidal simulation in which an interface shear coefficient of 0.003 is used are shown in Figs, 8.1a to 8.1e. Comparing with the current meter results in the Punta Arenas area, the model predicts somewhat smaller speed magnitudes, probably partly due to the use of a mean tidal range of 0.24 m. However, the model also shows fluctuations within a tidal period similar to those found in the observations. It appears that an internal seiche mode is excited by the tides. The hypothetical trajectories of particles in top or bottom layers are computed from the model results and shown in' Fig,. 8.2 which cover a 2.5 day period. These trajectories verify the previous findings that exchange in the bottom layer are very slow, while flushing in the top layer is of the order of 10 to 20 days with somewhat longer times applying to the southern part of the Bay, Perhaps the biggest surprise is found in the trajectory of the particle in the top layer just to the southeast of the Boca Chica opening, which shows a net motion away from the ocean. All the other particles in the top layer move towards the ocean as would be expected due to the constant freshwater inflow, A possible explanation could be that due to the topography, which in this 62 0.3 X -2-2 Bottom Layer Speed in cm/s -2.6 Surface Layer Fig. 8.1a. Predicted tidal currents in Cartagena Bay. Time = LW + 9000 sec. 63 6 'All > A Bottom Layer Speed in cm/s -2.3 Y .2-'. -.3.0 -3.6 6'r 1.4 Surface Layer Fig. 8.1b. Predicted tidal currents in Cartagena Bay Time P LW + 18000 sec. 64 -4. L C; e, -7.4 C@ E, -VI 3.2 4\ -2.3 e- X -2-7 q. Z- O-T-' Bottom Layer Speed in cm/s 4, 7 I.Z- m Layer Surface Layer Fig. 8.1c. Predicted tidal currents in Cartagena Bay Time = LW + 27000 sec. 65 6. tF V-0 Nr 0,4 Bottom Layer Speed in cm/s j.0 0.3 0A 4.7 0 0.7 AA O.S 4 JO@@ Surface Layer Fig. 8.1d. Predicted tidal currents in Cartagena Bay. Time - LW + 36000 sec. 66 4--J 05 -7 J -7.2 -3.8 4 6-q 0.3 +--3.3 Bottom Layer Speed in cm/s @2.4 DA .2.9 4.7 R-P L 4-e- S* r D-9 IY Surface Layer Fig. 8.1e, Predicted tidal currents in Cartagena Bay. Time LW + 45000 sec. 67 lee Bottom Layer Surface Layer Fig. 8.2 Predicted particle trajectories for tidal forcing. 68 area is complicated by islands, an embayment and several channels,a local eddy occurs in the residual currents. More field data should be collected to verify this phenomenon. 8.2 Southwesterly Winds During most of the year, when the Bay is stratified, the winds are moderate and variable. At times, a sea breeze is noticeable. The most dominant wind direction seems to be from the southwest. In order to evaluate the effect of such winds the model is forced by a wind of 5 m/s (= 10 ka) from due SW.Tidal flow and freshwater inflow of 75 m 3/s are included as before. The wind drag coefficient C D = (1.1 + 0.0536-5.0)103 2 0.001368, and the wind stress is 0.00004 N/m The computed velocity fields are shown in Figs, 8.3 a-8..3e. The most conspicuous differences compared to the pure tidal flow case are best demonstrated by the particle trajectories over 2.5 days shown in Fig. 8.4. . There is an obvious southerly migration of particles in the bottom layer, while the surface trajectories tend to follow the wind. It should be noted that no attempts were made to adjust the ocean boundary conditions to account for wind effects. The model is started from "cold" and run for 60000 sec, and in plotting the particle trajectories it is assumed that the velocity field computed during the latter 45000 sec repeat continuously. Although, such an assumption cannot be expected to be fully correct, the trend indicated by the trajectories should at least represent the water motion during the initial period of wind forcing. In the future it would be interesting 69 ct 19.A 0. 'A .10 v "1 0 Bottom Layer Speed in cm/s 10 < 14 14 'If %, '19 Al. Surface Layer v ej, Fig. 8.3a. Predicted currents in Cartagena Bay. Tide and SW wind. Time = LW + 9000 sec. 70 ci .3., qi@ lp. t4 cl, Bottom Layer Speed in cm/s .............. ..... . . @4 c;6 v r4 in c; V Z Surface Layer Fig. 8.3b. Predicted currents in Cartagena Bay. Tide and SW wind. Time = LW + 18000 sec. 71 .-3-0 Al c2 JD .6 Q .0.7 Bottom Layer - ------------ Speed in cm/s .0.8 A 6 A 03 0.2 C.0 v 0'0 Surface Layer Fig. 8.3c. Predicted currents in Cartagena Bay. Tide and SW wind. a-'r, om Layer Surface Layer Tivie LW + 27000 sec. 72 r, 6' Z' 9-a C." e4 Bottom Layer Speed in cm/s -2 -C Y >A > >!@ V/ a %@V Surface Layer Fig. 8.3d. Predicted currents in Cartagena Bay. Tide and SW wind. Time LW + 36000 sec. 73 0 - a r--+s r-+ 11 6 6'0 A - X 4 Bottom Layer Speed in cm/s .14V jb .1 c; 0.0 < q 4.8 0 VO iu N@* Surface Layer Fig. 8.3e. Predicted currents in Cartagena Bay. Tide and SW wind. Time = LW + 45000 sec. 74 Bottom Layer Surface Layer Fig. 8.4. Predicted particle trajector@es for tide with SW wind. 75 to compare these results with those obtained by running the model over a longer period. The particle trajectories tend to follow the wind cirection, how- ever, the velocity is somewhat smaller than those obtained with the drogues. This is possibly due to the oversimplification committed in the model in assuming the surface layer to be vertically homogeneous. To resolve the near surface wind driven currents it appears that at least a 3-layer model would be necessary. 8.3 Northerly Wind Strong winds out of the north persist during part of the winter months. During this period the stratification tends to break down because minimal freshwater inflow arrives to the Bay. The two layer model is therefore not applicable to describe the currents under these conditions, however, it may provide some information on the mechanisms instigating the destratification process, A wind of 20 kn from the north is applied in the model, which is again started from "cold". The tides are included as previously de- scribed. The computed velocity f ields are shown in Figs, 8.5a to 8.5e. Significant differences are found in both layers compared to the pure tidal situation, which is particularly evident in the particle trajectories shown in Fig.. 8.6. Due to the wind stress the surface adjusts with an upward slope in the downwind direction as the water is piled up against the southern boundary. This surface slope 76 '4.0 'J'e -2-4 :b -S.4 Bottom Layer Speed in cm/s- 9, r 1.0 7 0-0 Surface Layer Fig. 8.5a. Predicted currents in Cartagena Bay. Tide and N wind- Time = LW + 9000 sec. 77 Z.0 j.v .0 2,5 pw@ el .0 .2.2 -3.V .1.0 -2.4 Bottom Layer 0. Speed in emls ,e Vic "A \>,), .0 Surface Layer Fig, 8.5b. Predicted currents in Cartagena Bay. Tide and N wind. Time = LW + 18000 see. 78 -4.7 L A 'J.2 t .2-e -A.4 -2.2 -2-6 _-6-2 0.2 Bottom Layer 4 --- JO.0 Speed in cm/s 44 .0.6 IN 41% 9, r 9' C; < 7 7 Surface Layer X @O \-26 If2l'\ "-4 1@ D. Fig. 8.5c.. Predicted currents in Cartagena Bay. Tide and N wind. Time = LW + 27000 sec. 79 @A -6. t lb ,L .2-6 .2.1 P @Jqp -,3.8 -2.9 .6 .2-1 -3.0 Bottom Layer Speed in cm/s < s, r C-C- V Surface Layer .-C S-"r Fig. 8.5d. Predicted currents in Cartagena Bay. Tide and wind. Time = LW + 36000 sec. 80 -3-2 A- lb -2.6 J.5 4.6 Y -3.0 3.0 7. Bottom Layer Np Speed in cm/s 0.0, Surface Layer Fig. 8.5e. Predicted currents in Cartagena Bay. Tide and N wind. Time = LW,+ 45000 sec. 81 Bottom Layer I Surface Layer Fig. 8.6. Predicted particle trajectories for tide with N. wind. k, 82 is accompanied by the usual opposite interface slope as dictated by simple hydrostatics. When using an interfacial shear coefficient C, = 0.003 the interface reached the surface at the northern end of the Bay after approximately 50000 sec, and the simulation had to be stopped. By in- creasing C1 to 0.01 the top layer depth in the north is about 2 m after 60000 sec and approximately 8 m in the southernmost part of the Bay. The velocity fields shown are for C1 = 0.01, which is a very large almost un- realistic value. As previously mentioned the main objective of making this simulation is to learn more about the mixing mechanism due to wind rather than to obtain realistic current fields. For the latter purpose a different, perhaps unstratified model should be used. The most evident destratification mechanism seems to be the elevation of the interface in the northern part of the Bay which then allows exchange between the ocean at Boca Grande and more importantly allows the wind to directly affect what was previously the bottom layer. It is quite likely that breaking internal waves also are generated in this situation leading to further.mixing near the shores of the Bay. These briefly outlined phenomena have not yet been verified by field observations and are only considered as possible working hypotheses at present. 83 9. DISCUSSION Although the results obtained during this project are somewhat sketchy due to lack of sufficient current observations it is possible to perform a preliminary evaluation of existing and hypothetical scenarios. Two examples are considered in the following. It has been shown that the freshwater inflow from Canal del Dique plays an important role in the stratification and flow patterns of the Bay. There is considerable evidence that the stratification causes minimal exchange to take place in the bottom layer of water stretching from 6-10 m below surface and down. This evidence consists mainly in direct current observations, model results and measurements of dissolved oxygen. On the other hand a net flow is generated in the surface layer due to the significant influx from the Canal, and this residual flow helps flushing in the upper water column of the Bay, With this back- ground it is interesting to consider various alternatives for the future management of the canal. For example proposals have been formulated to dredge the canal to a greater depth in order to allow more shipping traffic. This in turn would probably result in an increase in the volume of water discharged by the Canal and therefore an even more distinct stratification in the Bay. Consequently, it is possible that the present destratification that occurs in the winter month and which provides some reprieve in terms of mixing and increased DO near the bottom would not occur or would be of shorter duration. A natural question is then, what would an optimal discharge from the Canal be? A simple answer can of course not be offered, however 84 experience in other places indicate that a partially mixed structure is desirable in terms of flushing and diversity of environmental con- ditions. Whether this is achievable without significant compromises in other areas seems to be a challenging subject for further research. The sewage outfall of Cartagena which is presently located in the northern part of the Bay near the Manzanillo island is another structure deserving some consideration in the future. The raw sewage is probably a major contributor to the pollution load of the Bay and questions of treatment and/or relocation of the outfall will eventually be posed. Since our analysis shows that in all probability the flow in the Bay surface layer containing much of the suspended or dissolved sewage would carry the pollutants towards the open ocean through the Boca Grande entrance, it would seem attractive to relocate the outfall closer to Boca Grande or even to outside of the Bay. A careful analysis of the amount of treatment and the optimal point of discharge for the city in the coming year is within the realm of the po@sible with the ,information and models developed in this project. 85 10. CONCLUSION Perhaps the most severe limitation to the efforts.of the hydrQ@ dynamic investigations of Cartagena Day has been the lack of a Colombian counterpart who was qualified and had time to take an active role in the data analysis and modeling effort. In spite of this, a number of Colombian individuals have been involved and trained in the design and actual process of data collection for a baseline study of the Bay. The collected data already yields a reasonable picture of the seasonal variations in flow and mixing characteristics, Progress towards describing the short term and smaller scale hydro- dynamics has been made with the development of a twolayer numerical model for the Bay. Additional field work is needed to calibrate and verify this model. In particular more data on current velocities and on Canal del Dique discharges are needed. The major highlights of our findings are that during the part of the year when the Bay is stratified there is a net flux of water out through the Boca Grande entrance. Estimates of flushing times due to tidal flow in the surface layer made from salinity data and using the model both result in approximately 10 days, Flushing in the bottom layer in this period is very slow because of the barrier at Boca Grande and the reduced vertical mixing, During the winter months when the stratification breaks down fairly rapid exchange is expected due to the strong northerly winds and en- hanced mixing. 86 Both the small amount of current data that has been analyzed and the model indicate that internal wayes exist when the Bay is stratified. These waves seem to have periods between 2-15 brs and cause significant currents of up to 5-10 cm/s. Thus they may contribute to horizontal mixing and vertical mixing if the waves break. The typical summer winds from SW can induce significant flows and exchange, especially in the bottom layer, The prime driving mechanism in this process is the setup in the surface as the surface water is piled up against a shoreline and the subsequent barotropic tilting of the interface. The strong northerly trade winds during winter may trigger the destratification process by inducing excessive tilt in the interface. However, the reduced inflow from Canal del Dique definitely also plays an important role. When the stratification in the Bay has been broken down'. the trade winds cause significant horizontal and vertical mixing and exchange. This is also corroborated by the analysis of water quality parameters and benthic communities. The stratification found in the Bay is overwhelmingly dominated by salinity variations. The temperature varies only little and ranges between 27 to 31*C over a year. The prime source of freshwater is the Canal del Dique, which reaches up to 200 m3Is at peak discharge periods. An interesting phenomenon for which considerable circumstantial evidence has been found is the possible sinking of the canal discharge due to its heavy sediment load. 87 ACKNOWLEDGEMENTS A number of people from the Center for Oceanographic and Hydrographic Investigation (CIOH) in Cartagena contributed in data collection and analysis, Also the facilities of CIOli have been gracefully put to our disposition. The counterparts on the hydrodynamics have been in succession Tns. Diaz, LaTorre, Capt. Steer and Tn. Alvarado. Chief of the scientific unit at CIOH, Mr. R. Parra also made valuable contribution to the outcome of the project. Finally, Tn, Kaleda and Medina also of CIOH deserve much appreciation for help with translation and the many problems that arose throughout our joint venture. From University of Miami Drs. Corcoran and Williams and Mr. M. Brown helped provide many good moments and stimulation through discussion of field work and results, Finally, appreciation is given to CCO and especially the Inter- national Sea Grant Programwhich supported our,efforts under Grant No. 04-8-Mol-166, 88 REFERENCES Cox, R. A. "The Physical properties of sea water" in Chemical oceanography, Edited by Riley, J. P., et. al., Vol. 1, Academic Press, London 1965. Dronkers, J. "Tidal computations in rivers and coastal waters," North-Holland Publishing Co., 1964. FAO/CCO. "Study concerning the mercury pollution of Cartagena Bay," Pollution assessment project report, 1978. Leimkuhler, W., et. al. "Two-dimensional finite element dispersion model," Proc. Symposium on Modeling Techniques, Modeling 75, ASCE, 1975. Schaus, R. H. "Circulacion y transporte de agrea en la Bahia de Cartagena de Indias," Document DO-20. Direcion general maritina y portuaria, September 1974. Wang, J. D. and Connor, J. J. "Mathematical modeling of near coastal circulation," TR200, R. M. Parsons Laboratory, Civil Engineering, Massachusetts Institute of Technology, Cambridge, Mass., 1975. Wang, J. D. "Real time flow in unstratified shallow water," J. Waterway, Port, Coastal and Ocean Division, ASCE, WW1, Feb. 1978. Weyl Peter, K. "The change in electrical conductance of seawater with temperature," Umino. and Oceano., Vol. 9, No. 1, Jan. 1964. 89 1 APPENDIX A Program for Salinity from Conductivity and Temperature ~0 ~p(~A~lTU~FAT~ JUN ~~4 ~~P~2p)~2p, TEMP, SAL) ~p5 -TFM~ C~p8~ A~s~~l~P~ ~U~ ~~ ~p*~ I ~~B~r~C~pL~ a F~pJ~~ 9 CL~pY~ to It-(AR C~L~0~ CL~ ~ ~pI~ 14 ~A~C~ is ~ ~ ~~2pi~AL 91 0 APPENDIX B Program for Harmonic,Analysis of Tides ~0 F I L ~1p' ~p@ ~ ~ ~1pQ ~~p@~8ATI I ~ (I T AA~pF F ~p/~l~9~ ~ ~F PF~1pR~2pO~pFN F~IES TO BE ANALYSEn~ 3 C ~~ FT~ ~ 1~N~'~) ~~) F~SIGMA (15~) ~ 5 ~ 7 8 ~IVAL~~, ~ CALL ~f) . 5 ~pn~ ~OT~n I e I ~ ~~r~pA~~ ~ 1, lip ~ ~ ~1pI~ 5 ~p"F~p0) ~~ TI j =!.,I ~~s~o~ I ~ I ~ ~pA AH ~~m~Z~~~ ~ ~~~~~GE 3~ I T F ~1p)~~ ~ 1 (~ ~f A TI ~~ ~~E~~j OF 1~ ;t~p0~I . ~ ~ 7~2pr-~pq ~j~ 'A ~ ~ ~I~1~K~ ~, ~ ~F ~ ~~y ~ ~pf I~pV ~2~m ~ ~ ~ ~1p@~1pt~pnA~ ~ r I ~ I, ~p-~t T 1~ ~~ I F~I P_ E ~1~7~ ~ ~~ ~ ~ ~ ~p=~ 3~ ~~ ~ ~ ~p(TI ~ ~ ~jU~ ~r L ~I ~ ~C ? 7 7 ~1~p1 Nr~ 39 ~ ~p(-~pl~~pI 2~ ~ It ~ 1~~ (~ I~~ ~~ ~1pe~ ~~ ~ ~~ ~~ ~~ ~2p4 ~2py ~ ~r~0 ~ ~ ~ C 3 ~ ~~1p!~ 5 ~ ~~~p! ~ 5~ 1~ ~ 5~ ~~1~1~M~ ~C I ~ F~2p'~P~ ~ ~2 *~5~ ~ ~~~ ~ ~ ~ ~N~ ~ 59 ~p" F~ ~ flu ~ AA~ h -~1p1~ ~pt.~ ~ ~ C ~ I F ~ T I ~pST~ ~ I ~ ~0 ~,~ ~ 1~~ ~ ~ 7~ PL~pF~ ~ ~A (~ ~i~ ~ 7 A~~ ~ ~ ~ ~~1pS~ ~ T~~p(A~ I ~ ~ ~2pT ~ ~ T I ~p1 ~pM~ 76 ~pF ~~.~ ~0 ~ Ila I ~~ ~p11 WTI , N~ AA~p1~~2p(~(J~ ~ ~;~AA~~ ~ 7 ~1pN ~1p,~ h (A CC. 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T I ~ ~O~ L~i~CONDS to DEGREES UNDERSTOOD. ~O~1 1 ~~AND SEC~p75 DEGREES UNDERSTOOD, ~O~2:~~O~ERS ~O~~~TION 8 ~2~B~ ~O~2p1~m IN ~RS ~OL ~ T~~ DEGREES ~ I C~ C~1pIV~1pH~ ~ 3~ ~ ~ 41~~)~ 4 C~p-4~pF~2pjR~C~ 15 COL ~9~2pj ~1pL MMHO/C ~~2~1pT.~1pT~ ~ ~: OF P T~1pfC~pR ~~p: T~~RE~ ~nL 59~ ~I~1pH~ 20 ~2p-64~~ 2~L ~~fPT~2pAETERS 2 C~ T~AT~pEES~ 2 C~ C~2pl~ ~/~ 24 C~~SAL~~ ~ ~ ~p0~1pO ~9~ ~~ ~p55~ ~ ~~pb~S~pa~ ~2pOS5~~ ~0~ ~~ ~~1p9~2p3~o~ ~p0~ ~0~ 0202905 ~ ~0 H~8~2~p~ 02 ~2~ ~0~ ~pS~ ~~ 29 HTC~p0~?~ 02 1202705~ ~~ 20~ 260260980 30 ~0~1p2~s~ ~1p0~~~ 02028~ ~~ ~1pHT~8~pp~ ~2p02~ ~ ~0 ~~ ~TC~P~p.~ ~~~2p5 ~p5~ ~~ ~TC~P~1pP 145 ~2p0~ ~~ ~~ ~9~ 34 ~~~pt4~ ~~2p05~p0 ~8~ 1~p85 ~~~ 95~ 04 12~ 15026~ 20~p5 ~6~ 3~1pI~p0 ~~ ~1p5 ~60 ~9556~pP~55~ ~~0 ~1pH~~ ~2p3~ LAS ~5~ ~~ ~pP~ ~~ 38 ~~ 910 ~ ~~ ~ 0~ 200269590 24~59~ 39 H~~ ~p0 ~ (~p(~ ~9~ ~1p6~ ~9~ ~ HT ~2 ~2~ ~p4~p0 ~1p8~8~ 1~2p5 ~1 ~pT ~pn~ ~2p02~ ~9~ ~0 2~p5~ 42 ~0~ ~L~ ~460 ~ ~555~ ~pSI~ ~IC~~2p3~ 07 ~~05~ ~~ ~~ 44 HT~80 ~P ~ ~2~ 150268590 25026559~ 5~ ~~~ ~po~ ~470 ~ 02029~ ~~ 46 ~~ ~~ 08 ~~~ ~v~ ~~ ~1pm~~ ~pl~9~OR ~ ~~~2p9126599~2~~ 48 ~0 0~~ 09 ~Oo459 0~ 020290570 ~~ ~~pb~~ 4~ ~p4028~ ~0 ~P~ 1~ ~TC~~p0~134~ ~1p0~ ~~ ~p985 24~2p5 ~2pMTC~~ or, ~ ~1p03~~~0 ~0~ ~~ ~~~ ~q~ ~2p028~ ~1p8~ 8~9~1pI~59~ 5 ~1p58~pO~3~ ~1p02~0 1502~ ~5~ 1~ ~1pH ~p50~1~9 25~ ~1p03~0 0~ ~1p57~~p0970 ~~5~p1~p0 ~1p02~ 05~ ~p59~ ~~ 5~C~pj~~0 11 120270590 15026759~~ 2~~ 57 ~9~12~32~ ~1p03~ ~p5~ 020295555 ~p57~ ~T ~~;2~ 12 0~ ~1p85 ~pS9~ J0~ ~TL~p2~~ I? ~~150267590 200265590 2~2p0 b~2p'~ ~1pj~ ~0~ ~~ ~p9~3~ ~~~8~m 3~ 02 0029 2~~ 92030296 3~ 352 ~1pHTC~~c~ 0~p,7~ 1590 02~ 64110284 3~ 3~ b3 HTC~1p0~j~ ~~ ~~69 0279 3~p77 368 64 H~~l~o 02 ~ 3~p1~~62~ ~ ~TC~1p0~~~ ~pJ~ 2770 0~ 330030294 352~ 351 ~~~ ~P~ 03 ~A~6~R4 3~2~ 36413~ 3~ b~1pI~1p09~~ 1~ 1~ ~~ 3~ ~1p7~2p3~ ~l ~p09~~ 03 17~ ~2~ 367 ~ ~I ~~~m3~ 04 ~p1~7020298 340040294 ~29~2p7 ~2p1~2p6~1p9~~ 04 ~ 3611 ~ ~2~ ~ ~ ~l~ 04 ~A279 366~ ~02~ 3~ ~ ~T -~ ~~ 149 04 240276 612~ 3~p77 ~ H~ ~ 1~h~p0~1p9~' In ~~1~l~99 33~ 3~ ~ ~ 09 ~ 63100284 364120283 ~~ 366 75 1 ~l~p9~9~2pq ~1p0~ ~~ ~pa76 ~0P~ ~ 7b H~t~o~~ 06 ~~~pb ~4~ ~~ 353 ~2pF~~pw~3~ ~2p0 ~~2 ~2~ 3~79 36~ ~TL~9~q~~ 06 ~~2~36 2~ ~ ~0 ~ HT~021 ~p9 07 000305 2~ 3~pq7 3~P94 34~ ~ HTC~2~~ ~p0 ~2p0 3~2~ 3~ ~p2~~ ~ H~~ 020 R~ ~02~ 36~p8 366190276 3~2~ ~ 8 ~ ~pP ~ ~pP~ 366 ~HT~1~ I ~~~ ~ ~1~1~4 3~p03 ~13~329 ~ ~ ~ 7~0 OR 050295 353~ 3~p02~ ~2~1p0 ~~~ I or, ~p0 ~p1 ~ 36~ ~02~ 36a~ 36~ ~ H~pI~ 0~p1~ ~pp~ 3~ ~~ 3~ ~~~1~ 7~15 e9 POOP 1 27601~ 2~1p8 3~ ~ ~ HT~~ ~2p7~5 ~p07~ ~0~ ~028~ 36413~ 365 89 ~~ ~M5 ~p02~ 366~ ~0279 ~~ ~ go ~Q ~S 72~5 09 ~~6~ ~ ~ HT~~I~ ~p0~ 222010308 ~~ 345~9~p35~ 92 H~2p4~34~ SO ~ 3540~- 359 93 HT~?~k~1pV~ 1~p)~ 2~ 33~ 3~1p0 ~ 9~ ~~~~0 I I ~~ 35 ~ 362100284 363~ 364 95 ~~1pO~V5~ 11 ~ 3671602~ 366180278 367 00276 ~ ~ ~2~p01~5~ I I ~ 3~ 3~ ~ HTC~2~1p1~ I ~1~ 2~1p1 285020298 337040293 352 98 m~p7~pM~S 12 ~2p1 3~1287 ~2p5 3~ ~ ~ ~d~2p12~1~ 12 ~ ~~ 3661802~ 3~ 366 too ~2~-~ 12 2~ 3682452~.361 1~ ~ ~03 20 ~~ 2~ 323 20294 344 3~ 3~ ~ ~6~p0~~ ~pI~ 348 ~ 348 ~ 348 ~~ ~ 103 ~p6~1~3~ ~p03~ 279 ~ ~ 338 6~ ~ ~ ~p79 9~A~ ~p1296 36~ 363120291 366~ 36~ ~H~ ~~pc~ ~1p0~ 369180284 ~ 3~ 3 ~ Sob HTC ~ ~m~l ~~ 3~2p1 ~0~ ~ ~ ~~1pe~3~ ~02 278 2~ ~ 333 6~ 3~ too H 1 ~9~M3~ ~1pq~211~ 36114~ 3671702~3~ ~ ~p0 b~~~ ~2p0~ 3~ 3~p$3 3~ ~ ~ b~1p?~4~ ~1p?~ 2~ 3~p0~ ~13~347 ~p@ ~21203 ~ a 90297 3~pq~ 35913~ 36~2p8 36 to H ~ ~2~ 45 ~1pR7 3~ ~ 3~ 353 11~pHT~2p6~pp~- ~ ~ ~ 32~ 3~ 14 ~p0 ~2pR20~ 25 9~ 3~ 59~ 367~ 368 ~ ~~pl ~2~ ~1pP8~37024~ ~ ~ HTC ~013 920 ~ ~p6 221 20302 ~1p1 328 ~ 3~ It? H~ ~ q~0 ~03~ 34~ 54~ 3~ 368 ~ ~ ~pi~313~ 6 ~7 370220~ 359 ~~ b~pP A~ ~~p2~ 329 40~ 332,~ 33~ ~ HTC ~ 032 ~ ~ ~~~ ~pt 3~ph~ 3b8 121 ~~ ~ I ~2p5 ? 21~ ~p2~ 3~ ~2p6~pO~p7~2 ~ ~ ~P3~ 3~1p5 32~0~~ ~ ~pb~2p0 ~2pt~ a 7~ 337 ~ 3 1 20291 36~ 36 24 H ~ ~~ 8 ~ 3 ~ 36824-2 3 3 ~ ~ ~HTC~9 ~ 7~p1 A ~3 3~ 26 ~~ ~p2~ ~9~ 20306 317 ~ ~1p3~ 339 21 H~6~ ~M ~ ~~~ 36~ 367 128 ~ ~ ~ 41~ ~~72 2~ 293 ~ 332 6029~5 ~PIC ~~q~5 to 9~ ~p92 360150291 ~ ~ ~0~~~ it ~ 27 2030 ?1 40299 32~ 346 131 ~ ~ ~ A 10~ ~ ~ 367 ~~~0 I 1 ~ 3~ ~1p029 ~ 364 is HTCI~~ 250 ~2A~69220285 3'692~ 3692~ ~ 33 ~6 ~~2p5 12 ~ 2~ ~ 3~ 335 ~~I~~p5 I? ~ 3451 ~ ~4 36~ 367 ~ ~791~i~ 12 ~ 3~ 369290283 36 ~ H~ 5~1p2~ ~~p2~ ~ 339 30298 347 137 ~0~ ~j~ I 4~ 347 ~ ~ ~ ~2p8~p9~~ ~2p1300 ~0~ 325 ~ ~ 337 ~ HTC1~ 9~~2p3~ ~0 340 50299 346 7~ 34 ~ 3~ ~ ~~ 9~~0 ~1p02~ 359130293 3~1p0 3~ 365 14 HTC1~ 91~2p0 ~pA2 36~2~ 3~ ~ ~p8~ 9~~ 59 ~~4 ~ ~ 285 30302 3~ 143 ~~ ~~~ A 403~36 0298 341 ~ 341 ~ ~ ~ 44 ~e~ 9~~ ~pP~~pq~ 35~S9~ 3~p8~1p3~ ~ ~~ ~~ ~ ~p;~ ~ H~ 94~~ 4 ~ 267 ~ ~p12 33~p~ 3~ ~H~~ 9~~ ~ ~1pq7 34? ~ 35~ 35 9~ 354 48 ~2880 94~ 45 4 ~ 3~289 35 150287 36~ 363 ~ H~S~ q 4~ ~ 4 2 ~ 365 ~ ~ ISO ~~ 9~~ ~2pr~p3~ 2~~ 297 ~ 317 3~ ~ ~ ~P~ ~p0 ~ 4~ 334 029~8 ~ ~pI~ ~ is ~2p0~p9~2p12~ ~ 3~ 348~ ~0~ ~ ~ 3~ ~ H~S~ ~~ ~28~ ~~ ~ ~p06 1~ H~ ~ ~ ~~ ~0~ ~ ~ ~ H~~~~3~ ~9~ 33~~ 33 ~ 33~ ~ ~ H~0~~1~ 6 ~ ~ ~~ 352~4 355 ~ H~~~p0~ ~1p@~ ~ 3~)~ 312 ~ 330 ~0 158 HT~p0~A~ 7 4~ 331 ~ 334 ~ 338 ~.~ 33~ 199 ~2~@q~1~ ~1~ ~0 349150288 35~p4 355 ~ H~2p01~25~ a ~ ~~p@~ 319 ~~3~ ~ H ~ 1 ~0 ~ ~2pq~ ~ 334 029~40 9~ 345 ~ HTCI~0 7~ A ~471~ 3~ 3502002~52 ~ ~~~I~ a ~ 356 1~ ~p88~~ 9 ~ 250 10300 ~3 311 30300 3~ ~ ~2~4~1p4~ 9 4~2 ~ 33~9~~pq~ ~ H~2p0 ~7~0~ ~1~343~ 34 5~ 347 0~3 167 H~1~4~ 9 ~ 3~ ~ ~~05~p4~ In ~ 244 1~ ~ 3~ 334 ~ H~a~0~~ 1~~p5~ 336 0292 342 9~ 3~ ~ HTL~p1~~ 1~1p;~347 ~8 ~1p8~9~~5 ~ HT~2pI~;~ to 028~~ 355 ~ ~01111 9 ~ 11 ~ 275 ~ 2~ 302 ~ 3~ 173 ~2~~~ It ~ 350 5~ 35~ 354 9~ 3~ 174 ~~t~~ I I ~l 363)3~ ~p0~ 363200282 369 1~ H~p6~~ 11 250281 3~p8~p@~ ~ ~2~?~1ps 215 1? ~ 263 ~ ~ 3015 3~ 335 ~ ~2~l~~5 ~~ 342 ~6 44 7~ 349 ~ 349~ ~ ~p8~72~ 12 t~~~1pi~ ~58 ~p82 3~ 179 H~a8~2~ 12 25~363290281 3b3 I ~ ~~~~?~ ~ 297 103~ 34~3~1p45 303~50 ~ ~2~I~,~ ~ 3~ ~ 1~ H~p6~pl~l~ ~ 297 10310 ~306 335 3~ 345 183 ~~~0 2 40299 350 5030~~p7 350 9~ 36~ ~ ~1p8~~3~ ~40292 ~~ 365 ~36~p7 36 ~ HT~~~g ~2pJ84 3~pg~2p74 ~ HTC ~~ 5 ~ 292 I~ ~06 323 3~ 34~ ~ H~p6~1p2~ ~~~p8 391 7~ 353 9~ 358 ~ ~~~pS 3 ~ 3~pq~2150291 36520~ ~ ~ 89 ~~~p2~ 3 ~ ~ ~~p~ 4 0314 2~ 2~6 331 3~ 3~ ~ ~W ~p7~ ~ 4~6 5~ 352 70296 356 ~ 399 ~ ~0~4~p,314~ 4 110293 3~ 363~ 3672~5 372 ~ H ~3~1p5 ~~~ ~ H ~~2p1~ ~ 28~ 2~10 29~ 328 ~ H ~~2~ ~1p0~~ ~p029~1p2 9~ ~ ~ H ~~0~ ~~~ 36~ 3b4~8~2p7 ~ ~ H ~4~p03129 ~ ~ ~ H~8~2pq~ ~pb 0311 ~ ~ 30~ 314 99 ~~~;~ 13~ 40303 328 ~ ~9~ ~ ~ ~ 4~ I ~~p5~~~ ~~291 36 15 3642~ 3 ~ 20~H C ~ SIP ~ ~p0~~ 29~p;~p02 3~ 338 20 ~~ ~~p4~ 40302 ~2p9~~ ~p0~ ~ 203 ~~~ ~8~1~ 36 15 288 3~ ~ 2~ HTC ~ ~p0 3 ~ ~2p18 2~p08 290 203~ 29~ ~ 205 H ~ ~~ a 4~ ~ ~ ~0~ 3~ 2~ 028~9 a I~ 349 ~ 5~1p8 K ~~ 3~ 36 ~ 2~A~ 20~~ ~~25~ 24~ 2~ H~4~~ ~p0~84 1~ 2~A3~2 3~O 333 ~ HT~ 7~ 9 4~7 5~ ~94 ~~7 2~ ~0 54~7~ 9 1~ ~~~29~ S~ 354 ~ HT~p0 5~p1 ~ 9 2~ ~ 2 H~ 555 ~ ~~ 311 ~ 311 2~ 334 3~ ~ 2 ~~5~ ~S 4 1~1 49130~ ~ 33~ 341 ~ 3~ 2~ HTC~0~ ~ ~pV~~~ 34~ 3522~ ~ 215 H~8~~~ ~ 3~p8~2p9~ 14 ~ ~~ ~ ~~~ 250 ~p0~~ ~ ~ 32~ ~ ~OA~32~ ~02~ 50295 339 ~ 341 9~ 344 21~H~p60~ 250 It ~p7~ 4~9~p4820~ ~ ~ HC1~1p0~ 11 ~ 3~p8~ 220 ~ ~L~5 12 ~72 1~ 0305 315 3~ 3~ 22~H~~1pP~~ ~0299 335 50297 38 ~ 341 9~ 343 222 ~~~s ~ ~~461 3~ 347150291 35~ 358 223 H~8~6~~ ~.02~~ 224 H~~1p1~p0~ I ~P~05~p9~~~p2~ 225 HC~~p0~ ~2p9~5 650502785~ ~~6 ~1~ ~ T T 3 ~ ~ 3 ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ T T T T I T ~ ~~43~1pP~ ~~pg~~ 22~H~14~P ~ ~~2pS~6b~9150271585369 ~pq~1p2~ ~~p0~q~ ~ ~ 2 9 HrC~pS~0~ ~~5305027557936 ~0150211587370 230 ~p09~~~ 04 20027~~0~~ 231 H~9~1p0~ ~~5~p5~~p9~ 2~ ~2p;~~~p58~ ~ ~~~2~ ~1pV~ 97~pi~p3~2pP58~ 23~H~W~~~ ~ ~p58~ 235 H~2pl~ ~ 07 ~~1857335~5~ 236 ~1p1~p0~ 07 20027~86371 ~0 ~ ~9~ 1~pl~ ~~~49~p9~36515~~ ~ ~1p@ 2 ~9 ~ .~ ~~1p7~1p371 ~ H~g~I 5~2p)~-~ ~~~2p0278575360100275579363~71 ~ ~pM~1p7~ 2~ ~839633480502775733~027~pO27~s7~ ~ HtC~p1 I ~ I Q~5 ~1pi271~02?05~ ~ 2~ 1 ~pS7~pV~~2p(~~ ~ Ht~p1 1~2~ ~p02~~7~ 245 ~9~p1~532~ 2 ~35 05~~pV~6~p?~p7~ 2~1pTL~A ~~ ~pC~7125~2891270585371 ~ ~621~~ A~1 3 ~~1p0~ 1~58~1pP~ ~ 2~pHTC~1~ A~ ~2pO~2p72 2~p@~pT8~@ A~9 ~pI~2p05~p579~pd27~g~ ~ ~~~ ~ ~1p0272~3~ 2~ HTC~~ ~3~p5 ~~5324~12~~2p69~p,~72 25~1pC~I~~~ ~2~~1pi 253 ~1pb~ ~~ It, ~pP~~2p)~2pt~99~ ~ ~1~1~1p39 1~11~~~0~15~,9~ ~ ~j~~~ 17 ~~~1p?~ 25~HT~p1~1p793~ IS ~p.~0~~pI2~1p41 257 H~~p5~p25~ ~p1~- ~~p?3~27~p7~ ~ ~ H~V~3~~ ~p0~1p1~9545339 ~p2I~5~~p5 07 ~g~3~I2~10~5~ ~ HrCo~p2~,~ ~~~pJ2~364 ~ HT~H O~ ~ r~ ~ ~pj~R ~ CJ~p-~~ ~ COL 14~ LAT~~ AND SECONDS 1~ UNDERST~ 2b5 ~ 1~ ~~MINUTES AN~~ ~UN~2pD. 2~pCUL 22~ Tn~ DEPTH IN METERS ~ ~p24-25~pv~IF~ ~ ~-2~1pnTA~ 2~ ~9 T~nI~ SlJRFACE. ~ C~2p1 T~~ IN JT~ ~ ?~ ~~ ~ ~ ~LA. 2~ ~p18 ~r~p5~pP ~ ~ ~ 273 ~~R ~~ ~ ~Is ~ ~ ~ ~~p@ 2~p3~p04~ ~ ~ 2~pH~021~ 24~9 0~ 1? 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~ ~P~ 27~ 3~ ~ ~ H~6~ ~ ~ 2 2 2~ 339 H~ ~p3~ 29~ 2~ 340 HT~b~ ~~ 3~ 2.3 ~ H~~ ~~~b ~ 2 34~ ~6~ 2~~ ~ ~ ~ ~2~ ~~4~ ~ 4 ~2p6~ ~ ~p9~ 2~ 3.2 ~ HT~~ ~ ~ 3~ 2~ ~ 3~ ~2p6~ ~~ ~ 2.3 ~ 347 ~p6~ ~ 399~ 3:~ 2~ 348 ~pO~ ~ ~o 2 ~ 349 ~2~ 2~1p%9 ~ ~ 1~ ~ ~~ 2~?5~02001 4~ IS ~I~ 24~p8 03~ 7 ~~ 2~p0 (a ~p5 4~ 35 35 ~~ 2~p55 05008 ~ 354 H~1pl 2~p0 06~ 3.7 355 ~2pb~ ~ ~ ~ ~ 35~ ~2~ 2~ ~ 2~ 2.7 357 H~~ ~4~ ~ ~ ?.1 3~ ~~ ~ ~ 31. ~ ~~ 2~pj I A I ~ ~ 7 ~ 3~ ~p12 7 ~ ~ 12~ ~ ~ ~p7~ 2 ~1p1~2p3~ ~ 4 2 ~ ~p2 7 ~ 2~ 15~ 2~ 2~ ~ ~2~ ~ 1~q ~ 364 ~~ ~4~0 ~~ 5~ ~ ~~ ~ ~ ~ 3~ ~1pe~ ~ 33~7 ~ ~ ~ H~~ ~ 2~ 2,8 ~ ~ HTU~ ~ 21 ~ Is$ 2.4 ~ HTU~ A~ ~ ~ 3~ HT~ ~ ~ 3~ 2 37~ H~8~ ~ 3~ 3~ HTU~ ~~2 3~ HTU~ ~ 2~ ~ ~ ~ H I L~81 ~ ~ ~ 3~ ~ 3~ HT~ ~ ~ ~ ~ ~ HTU~ ~?3~ 9 ~ ~ H~ ~ 0025 5~ ~ ~ HTU~ ~ 3~ 79 HTL~ 2~2p8 3~ 5 ~95~ a ~ ~ 2 ~ 1 3~ 3~ 3 ~2p0~ 21~ 3~ 3~ 4 ~ ~ ~~ 2~S~ 35 83 ~2p08 ~0~ 36 ~ ~~ ~~ 37~ 5~ 8 3 3 ~ ~ 3 ~ 3 3 ~ ~~ 10233157 ~ 3~ ~ HTU~~ ~~ ~ ~ 6,3 ~ HT~0~ ~l~ 4~ ~ ~ 388 HI~6 ~1~ ~ so 3~ HT~4o~ ~P~ ~ 5~ 390 HT~4~1 ~~ 0~ 4 ~ 2 5 39~ HT~p, ~32~ ~ ~ 1 ~ ~ Hl~~ ~ ~ 0500~ ~ ~ 393 ~~ 215932~ ~ 3~ 39~ ~~ 2~ 0~ 3~ 2.3 ~0 ~ ~~ 2~pl ~ ~ ~1 ~ ~ ~1~~ ~p@~ Q ~ ~ ~ ~ ~3~ 1 ~ 1 ~ ~ HT( ~ ~3~ ~ 4~ ~~ ~~ ~ ~ ~~p- ~2~ 4~ HT~u~ 2~,~ ~4 ~ ~ ~ ~~p1 2~1pS~~ 3,3 ~ ~ ~1p@~ ~~ I SOO ~ 4.3 49~ H T ~p4 ~ ~ ~~ ~ ~ ~ ~1p5~ ~1pP ~7~ ~ 5. 4~ ~~ 2 ~ 3 ~ ~. I ~ ~ HT~4~ ~p2 ~ 7 ~ ~ ~ ~~ ~ ~1 ~ ~ ~ H~:9~1 ~q~~ ~ 2~ 409 ~0~ ~ 2~5 3.8 ~ ~ ~~ I A ~ 1 23~ ~ ~ ~0~ ~1pI 2~ is ~ ~ ~ ~~ 1~ 25~ 2~ ~ ~1pt~ ~~ ~ 3~ ~ ~2p, ~p1~~~ ~ ~ 4~ 415 ~pi ~2p4 ~l~t~8 ~ ~ ~ 41~ ~5 ~p3 ~g~ 902 ~ 3~ 417 ~1pk~p6 1 ~p3~ ~ 3.2 2~ ~ ~pS ~ t~po ~ ~ ~ ~ 1.- 1 ~ ~1p? ~1 ~t ~ 3~ 42~ ~p, ~2p6 ?1 ~3~~ ~ 6 ~ ~ HT~~ ~q ~ 3~ ~ ~ ~1p05~ 2~p5~pr~ ~ 7 ~ 42 ~pj~~ ~3~ ~ 9~ 2~ ~ HT~4~ I A ~ 3~ ~ ~ 425 HT~~ I A~ ~pP~2~ 3~ ~ H~c~ ~7~ ~ ~ 5.3 42~ H~~ 1~ 4~ 4~ 428 ~2p4 81 2~1p19 41 ~ ~ 2.9 ~ ~~ I ~7 ~ 3~ 430 ~pHA~ C~ENIS 43 ~~2pT~pR OF ~IME (T~IC CONSTANTS ~ CUL 1~TT~REFERFN~ ~ 4~ COL ~: ~l~ AND ~ to DEGREES UNDERST~ ~ ~~ES AND SECOND I DEGREES UND~ ~ ~; T~ ~ r~p@-~ FP~NCy~P~~ 437 ~O~ LI~ ~ C~71~INF AMPLITUDE 439 HT~6~~~g~ 2~ 6 ~ ~ ~ ~22~02~p0~ 1-~ ~ 3~ 441 ~~9~~~R ~ ~ ~ 44 HT ~p09~~H0G~ ~p4 ~ .~ 4~ ~7~0~5 ~O~ 3 ~ 1 ~ P~ ~ ~1p?~~@~p1~P 2~ 265 -A ~ ~ ~~~)~p0~ ~~ ~ ~i~ ~ HT~~~9 ~ R 5 5854 155 ~~ ~ H~2pQ~0~ ~ ~0~1p.~-~ ~ H~b8~~p9~ ~ 2 ~ 4~ ~ H~1po ~.~H 15.~ ~ ~ 450 H~pb8~l~1pP~ ~ ~ ~ ~ ~0~~1p0~ ~ ~ ~ ~ H~pb~A~~CH 2~ 2 ~ 2 ~ 453 H~b8~~p0~ ~p1 ~5 ~ ~ H~~3~3~nc~ ~8~ a ~ ~ 455 ~p6~~3~~ 15,5854 ~~~~ ~ ~2pr~~j~. ~ ~- 9~nNT~pR n~pT TIME ~ CUL ~ START TIME ~ C~ ~I~1pf~p5 ~ So DEGREES N UN~pOD ~ C~~ L~ M~ SEC~ DEGREES ~T~ ~ COL 22~~OW SURFACE. 4~ CUL C~~V~ 4~ C~~EF~ ~ C~~ U~2pO~ ~T~ 465 ~1pK~pG~ LIKE C~1p0 ON, ~2pOR M~ ~ P~~~ 8 MINUTES ~ Hk~~ ~1ps~M ~ H~p8~ ~0 4 ~407033~09~03~R~po~~ ~ ~04~ 2 ~p1 4~29~09~0 ~2p9~~09~~ ~ ~~ 2~ ~ ~ ~99~1~ HkC~ ~101 3~p5A~p19~0~ ~pX~pJ ~0~ 83~ 412 H~pd~ 21~ 4M~p1~92~~1p05 ~1pv~i~82~ 4~ ~04~ ~2~4 ~q~2100419303199~03~2~3804~ f~ ~0 ~ H~p8~ ~~ ~p0 ~1pI ~ 9 ~2p0 9 3 ~2p0 9 ~? ~p0 3 3 ~ ~ ~pq~ ~ ~1pe~33~01022~~~~ 476 ~~ ~8~pAM ~006~I431~p0~8~~ 47~pH~~ 21~p0~1134~204348~pS35b~pT~2p705~ 41~1pNC~1 1932~~8~pP~4~1p0~ 479 ~1p81~ H~p5~ 2~ 2~ 122~6~pS21~2p0~~1~p0901~ 4891 H~~ ~I~ ~~Ob~p04~1p1~p0~1p8~~i~ 481 ~ 2119 2~~~p7~po2~9~6~ ~H~pd~ 2~l ~714110 25 6304 ?~~9~~ ~ ~~ ~;3~ ~~0 112 ~ 8~1p1~8~ 484 ~1 ~S 04 ~6 9185 81~1p1~p?1~ 48~ ~O~ ~0 H~pb 2 ~POO ~4~ 8 ~231~ ~ ~9~ 4 ~2pW~8 2 ~p0~ 83~3 2 ~06 825812 9~@~f ~ ~~ 2~2p0 ~2~p1~9~1~~1po ~~ ~ ~~ ~p0~A~~19~~ ~A ~~ ~ ~ ~~ I ~ 2 ~p3~ ~1~1p017~ 3113 8 ~p12113 7 991 98 4Y~1pRC~ 21~ AM 91~1pt~ 4 33 4353 ~3~ ~ 491 ~~ 21~ 4M~p9~ 4~58 3~4 3~1~ ~ H~ ~ ~18~2 ~ ~ ~ ~2p. 8202 ~3242 ~ ~04~ ~P~ ~ ~5 44 9 3~ 3 2~3 5 1~ ~ H~ 21~O 4M~ I l~ ~2p6 5 12 ~ 8 ~2~ ~ HkC~ 2~0~ to 1~ 812 ~~ ~355 4~ ~~ ~~ AM ~ 9 9 8 5 12 7 ~ 3 3~ 8 7 49 HR~ 2~ 4 ~p1~ 44 9 201~ ~10334 ~p2~ 49~pH~~ 2~pO ~728~ 821234 ~ ~41~p018~ HRC~ 5~ 7~ 7162 ~ 2~ ~ ~ 76 ~1p820~~~ Soo ~~~~ 4M~21~ ~ ~1ps 68 8 3~ 'OR H~ 21~I~ ~02~ 22~ ~ 2~82 726~1p8~ 247~ DATE DUE GAYLORDINo. 2333 PRINTFO IN J S A I I 111 ll @@l 111111 1@ I I 1@ 111111! 11111111111 i - 3 66613 14106 4271