Simulation of Watersheds Hydrology Under Different Hydro-Climatic Settings
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Simulation of Watersheds Hydrology under Different Hydro-Climatic Settings A dissertation submitted to the Graduate School of the University of Cincinnati In partial fulfillment of the requirement for the degree of Doctor of Philosophy In the Department of Geography of the College of Arts and Sciences by Thushara D Ranatunga B.Sc. Agricultural Engineering, University of Peradeniya, Sri Lanka, 2005 M.A. GIS and Remote Sensing, University of Cincinnati, 2008 Committee Chair: Dr. Susanna Tong Committee members: Dr. Richard Beck Dr. Hongxing Liu Dr. Tomasz Stepinski Dr. Jeffrey Yang December 2014 ABSTRACT Hydrological characteristics of a watershed are dependent on a variety of factors, including the local climate, land use, soil, and other anthropogenic influences. Changes in these factors unequivocally would affect the water resources. To ensure that we will have adequate water supply in the future, we need a methodology that would enable us to predict the hydrologic ramifications caused by potential changes of the above mentioned factors. Furthermore, there is a need for new integrative approaches that model not only the separate but also the combined impacts of these changes as they act in tandem with each other. It is also important to understand the relationships between different variables and the underlying watershed processes under different environmental settings in order to adapt, respond, and make efficient water resource management decisions. The objectives of this dissertation are (i) to develop a tool/protocol to better understand the watershed systems and to help planners/resource managers to explore and predict the impacts of potential changes in climate, land use, and population, through basin scale watershed modeling; (ii) to introduce a total water management approach to help in managing the future potential changes in demand and supply of water; and (iii) to develop an approach to investigate the watershed characteristics and processes that control the hydrologic behaviors of the watersheds. The watershed hydrologic model, the Hydrological Simulation Program-FORTRAN (HSPF) and Normalized Root Mean Square Error (NRMSE) technique with Flow Duration Curve analysis were employed in this dissertation research project as the major assessment tools. These tools were applied to two watersheds, the Little Miami River (LMR) and the Las Vegas Wash (LVW) watersheds that are located under different hydro-climatic settings. From the results, it seemed that the tool developed could be helpful in facilitating the prediction of the plausible hydrologic consequences of climate, population, and land use changes. The simulation results also highlighted the extent to which different ii global change factors could amplify the hydrologic effects at a watershed scale. Moreover, the results revealed that the hydrology in the LMR watershed is mostly sensitive to groundwater related parameters, whereas the LVW watershed is related to near surface soil parameters. Furthermore, high and medium flows are the most sensitive flow regimes to most of watershed processes. iii iv ACKNOWLEDGEMENT First and foremost I would like to express my deepest gratitude to my supervisor, Dr. Susanna Tong, whose constant guidance, patience and caring helped me in completing this study, from the dissertation proposal up to the publishing of journal manuscripts and submitting the final dissertation. Without her guidance, endless advice and persistent help, this study would not have been possible. There is no word or thought that can adequately capture my gratitude for all her support in shaping up my academic and professional career. Secondly, I would like to thank to Dr. Jeffery Yang, from the USEPA, who provided me the opportunity to work at the USEPA and for his guidance and support throughout this study. I would also like to thank to the other members of my dissertation committee, Dr. Richard Beck, Dr. Hogxing Liu, and Dr. Tomasz Stepinski for their valuable inputs and guidance. To the faculty, staff, and most importantly to my colleagues at the Department of Geography, thank you for making each day of my stay at the department memorable. Without you all, my college experience would have been significantly less awesome. I would like to thank my parents, parents-in-law, and my brother and sisters. They were always supporting me and encouraging me with their best wishes. Finally to my wonderful wife, Sewwandi Rathnayake, thank you for all her support, love and understanding. She is always there cheering me up, and standing by me through the good and bad times. v TABLE OF CONTENT Abstract …………………………………………………………………………………………………………………………………………………… ii Acknowledgement …………………………………………………………………………………………………………………………………… v Table of Content …………………………………………………………………………………………………………………………............ vi List of Figures ………………………………………………………………………………………………………………………………………….. ix List of Tables ……………………………………………………………………………………………………………………………………………. xi Chapter 1: Introduction ……………………………………………………………………………………………………………………………. 1 Chapter 2: Predicting Plausible Impacts of Sets of Climate and Land Use Change Scenarios on Water Resources ………………………………………………………………………………………………………………………………………………… 5 2.1. Introduction ………………………………………………………………………………………………………………………………. 5 2.2. Materials and Methods ……………………………………………………………………………………………………………… 6 2.2.1. Study Area ………………………………………………………………………………………………………………………… 6 2.2.2. Development of a hydrologic and water quality model …………………………………………………… 7 2.2.3. The hydrologic model for the LMR watershed …………………………………………………………………. 8 2.2.4. The water quality model for the LMR watershed …………………………………………………………….. 8 2.2.5. Generation of the future climate change scenarios …………………………………………………………. 8 2.2.6. Generation of the future land use change scenarios ………………………………………………………. 9 2.2.7. Development of a CA-Markov land use model for the LMR watershed ………………………….. 9 2.2.8. Prediction of future population growth ……………………………………………………………………………. 11 2.2.9. Incorporation of the population variable in the CA-Markov land use model …………………… 11 2.2.10. The 2050 land use change scenario for the LMR watershed ……….………………………………….. 11 2.2.11. Modeling of the hydrologic and water quality impact of climate, population and land use changes………………………………………………………………………………………………………………………………………… 11 vi 2.3. Results and discussion ………………………………………………………………………………………………………………… 14 2.4. Conclusion ………………………………………………………………………………………………………………………………….. 15 2.5. Reference ……………………………………………………………………………………………………………………………………. 16 Chapter 3: A Total Water Management Analysis of the Las Vegas Wash Watershed, Nevada …………………………………………………………………………………………………………………………….. 18 3.1. Introduction ………………………………………………………………………………………………………………………………. 18 3.2. Study Area …………………………………………………………………………………………………………………………………. 20 3.3. Research Methodology ……………………………………………………………………………………………………………… 22 3.3.1. Developing the HSPF watershed model for the Las Vegas Wash watershed ……………………. 22 3.3.2. Formulating future climate change scenarios …………………………………………………………………… 25 3.3.3. Projecting population growth in the Las Vegas Valley ……………………………………………………… 27 3.3.4. Estimating future wastewater discharge ………………………………………………………………………….. 28 3.3.5. Generating future land use change scenario …………………………………………………………………….. 29 3.3.6. Simulation of Las Vegas Wash hydrology under the impacts of climate, land use, and wastewater changes ………………………………………………………………………………………………………….. 31 3.3.7. Assessing the future water supply and demand ………………………………………………………………… 32 3.4. Results and Discussion ……………………………………………………………………………………………………………….. 32 3.4.1. Simulated stream discharge ……………………………………………………………………………………………… 32 3.4.2. Total water management …………………………………………………………………………………………………. 37 3.5. Conclusion ……………………………………………………………………………………………………………………………….... 39 3.6. References …………………………………………………………………………………………………………………………………. 40 Chapter 4: An Approach to Sensitivity Analysis in Watershed Hydrologic Modeling ………………………………. 43 4.1. Introduction ………………………………………………………………………………………………………………………………. 43 vii 4.2. Methods ……………………………………………………………………………………………………………………………………. 48 4.2.1. Study area ………………………………………………………………………………………………………………………….. 48 4.2.1.1. The LMR watershed ……………………………………………………………………………………………….. 48 4.2.1.2. The LVW watershed ……………………………………………………………………………………………….. 49 4.2.2. Model selection ………………………………………………………………………………………………………………… 51 4.2.3. Model Parameter selection ……………………………………………………………………………………………… 52 4.2.4. Defining flow regimes using flow duration curve analysis ……………………………………………….. 54 4.2.5. Sensitivity index ………………………………………………………………………………………………………………… 56 4.3. Results and discussion ……………………………………………………………………………………………………………….. 58 4.3.1. Flow duration curves and flow regimes of the two watersheds ………………………………………. 58 4.3.2. Parameter sensitivity ………………………………………………………………………………………………………… 60 4.3.3. Parameter sensitivity under different flow regimes …………………………………………………………. 67 4.4. Conclusion …………………………………………………………………………………………………………………………………. 72 4.5. References …………………………………………………………………………………………………………………………………. 76 Chapter 5: Conclusion ………………………………………………………………………………………………………………………………. 83 Bibliography …………………………………………………………………………………………………………………………………………….. 88 viii LIST OF FIGURES Figure 2.1: The Little Miami River watershed study area …………………………………………………………………………. 7 Figure 2.2: Land use maps of the Little Miami River Basin acquired from the 1980, 1992, and 2001 NLCD datasets …………………………………………………………………………………………………………………………………………………… 10 Figure 2.3: Projected