SIMULATION OF PHYSICAL AND CHEMIC AL PROCESSES IN RESERVOIRS: TWO CASE STUDIES Selma L. Garcia Iturbe, B.A., M.S. Dissertation Prepared for the Degree of DOCTOR OF PHILOSOPHY UNIVERSITY OF NORTH TEXAS December 2005 APPROVED: Miguel Acevedo, Major Professor Samuel F. Atkinson, Committee Member Kenneth Dickson, Committee Member William T. Waller, Committee Member Thomas La Point, Committee Member and Graduate Program Coordinator for Environmental Sciences Art Goven, Chair of the Department of Biological Sciences Sandra L. Terrell, Dean of the Robert B. Toulouse School of Graduate Studies García Iturbe, Selma L., Simulation of physical and chemical processes in reservoirs: Two case studies. Doctor of Philosophy (Environmental Science), December 2005, 206 pp., 64 tables, 65 illustrations, references, 61 titles. Managing water quality aspects requires the use of integrative tools that allow a holistic approach to this problem. Water quality models coupled to hydrodynamic models are these tools. This study presents the application of the water quality model WASP coupled to the hydrodynamic model DYNHYD for two distinct reservoirs: Lake Texoma and Tocoma Reservoir. Modeling the former included simulations of water velocities, water level, and four chemical and physical compounds: chlorides, dissolved oxygen (DO), biochemical oxygen demand (BOD), and total suspended solids (TSS); and validation of the results by comparing with observed values during March – May, 1997. The latter is still under project status and the simulation was performed in a prospective way. The analysis included simulations of water velocities under current and for expected conditions, DO and BOD. Both models, DYNHYD and WASP, fitted pretty well to observed conditions for Lake Texoma and for where Tocoma Reservoir has been planned. Considering management and decision support purposes, the role of boundary and loading conditions also was tested. For Lake Texoma, controlling boundary conditions for chlorides is a determinant factor for water quality of the system. However, DO and TSS in the reservoir are governed by additional process besides the condition of the boundary. Estimated loadings for this system did not provided significant effects, even though the allocation of a load for chlorides resulted in significant changes in the trend for expected chloride concentrations at the Washita River Arm of Lake Texoma. For Tocoma Reservoir, the expected concentration of DO all over the reservoir is going to driven by boundary conditions, as well as by the management of autochthonous BOD loadings provided by vegetation decomposition. These two factors will be determinant for the resulting water quality of the future reservoir. Copyright 2005 by Selma L. Garcia Iturbe ii ACKNOWLEDGEMENTS I would like to thank her dissertation adviser Dr. Miguel Acevedo for his guidance and support on this study. Many thanks are due Dr. William Thomas Waller for providing invaluable advice during all the stages of this work. I also wish to acknowledge Dr. Samuel Atkinson, Dr. Kenneth Dickson and Dr. Thomas La Point, members of the committee, for their advice. I would also like to thank my fellow graduate student Alexandra Christina Upton for her friendship and support during most of the stages of this study. Finally, I am grateful for the financial support of this research provided by CVG EDELCA in Venezuela, the U.S. Environmental Protection Agency and the U.S. Army Corp of Engineers. iii TABLE OF CONTENTS Page ACKNOWLEDGMENTS ...........................................................................................................iii LIST OF TABLES.......................................................................................................................vi LIST OF ILLUSTRATIONS........................................................................................................ x Chapters 1. INTRODUCTION ................................................................................................ 1 2. HYDRODYNAMIC SIMULATION................................................................... 7 Model Description .................................................................................... 9 Lake Texoma: Description of the Study Area ........................................ 10 Model Parameterization for Lake Texoma ............................................. 15 Hydrodynamic Modeling Results for Lake Texoma .............................. 26 Tocoma Reservoir: Description of the Study Area................................. 33 Model Parameterization for Tocoma Reservoir...................................... 37 Hydrodynamic Model Results for Tocoma Reservoir............................ 44 3. RESERVOIR WATER QUALITY MODELING.............................................. 50 Model Description .................................................................................. 51 Previous Water Quality Studies of Lake Texoma................................... 54 Water Quality Model Parameterization for Lake Texoma ..................... 56 Water Quality Modeling Results for Lake Texoma................................ 78 Water Quality Studies for Tocoma Reservoir......................................... 95 Water Quality Model Parameterization for Tocoma Reservoir.............. 98 Water Quality Modeling Results for Tocoma Reservoir ...................... 108 4. ROLE OF BOUNDARY CONDITIONS AND LOADINGS IN WATER QUALITY SIMULATIONS............................................................................. 115 Sensitivity Analysis to Upstream Boundary Conditions ...................... 115 Sensitivity Analysis for Loading Conditions........................................ 122 5. CONCLUSIONS............................................................................................... 130 iv Appendices A. GEOMETRY DATA FOR LAKE TEXOMA MODEL .................................. 136 B. ESTIMATIONS OF TRAVEL TIME FOR LAKE TEXOMA MODEL ........ 139 C. GEOMETRY DATA FOR TOCOMA RESERVOIR MODEL....................... 141 D. ESTIMATIONS OF HYDRAULIC TRAVEL TIME FOR TOCOMA RESERVOIR .................................................................................................... 145 E. INPUT DATA FOR WATER QUALITY SIMULATION OF LAKE TEXOMA ........................................................................................................................... 148 F. STATISTICAL ANALYSIS FOR DEVELOPING INITIAL CONDITIONS FOR LAKE TEXOMA WATER QUALITY MODEL............................................. 168 G. STATISTICAL ANALYSIS FOR DEVELOPING DAILY BOUNDARY CONDITIONS FOR LAKE TEXOMA WATER QUALITY MODEL .......... 174 H. VALUES FOR TESTING SENSITIVITY TO BOUNDARY CONDITIONS ........................................................................................................................... 182 I. VALUES FOR TESTING SENSITIVITY TO LOADING CONDITIONS.... 193 REFERENCES ......................................................................................................................... 201 v LIST OF TABLES Page 1. Some morphometric characteristics of Lake Texoma, Tocoma Reservoir, and their watersheds......................................................................................................................... 6 2. Distribution of annual volumes in Lake Texoma for different usages (Compiled from TWDB 2003) .................................................................................................................. 10 3. Some morphometric characteristics of Lake Texoma and its basin ............................... 11 4. Main creeks that drain directly into Lake Texoma ......................................................... 15 5. Estimation of maximum time step (in seconds) for different conditions of water velocity and depth of the channels in the developed hydrodynamic network for Lake Texoma ......................................................................................................................................... 22 6. Time step values for different junction depths of the hydrodynamic network for Tocoma Reservoir......................................................................................................................... 42 7. Predicted and measured velocities for Tocoma under river condition ........................... 45 8. Relative change of water velocities for Caroni River when comparing river and reservoir condition at Tocoma site................................................................................................. 46 9. General characteristics of segments used in WASP for Lake Texoma .......................... 58 10. Relationship between water quality segments identification and station identification used by Atkinson et al. (1999) ................................................................................................ 59 11. Some constants and rates used by WASP for water quality simulation ......................... 60 12. Different loading conditions evaluated for Lake Texoma .............................................. 65 13. Identification of routine stations monitored by Atkinson et al. (1999) in Lake Texoma and their estimated location................................................................................................... 66 14. Estimated initial concentrations of chlorides for Washita and Red River arms for WASP calibration ....................................................................................................................... 69 15. Equations used to calculate daily concentrations