Development of Decision Support Tools for Water Energy Food Infrastructure Management of Sri Lanka By Thushara De Silva Manikkuwahandi Dissertation Submitted to the Faculty of the Graduate School of Vanderbilt University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY in Environmental Engineering January 31, 2020 Nashville, Tennessee Approved: George Hornberger Ph.D Hiba Baroud Ph.D Jonathan Gilligan Ph.D Douglas Adams Ph.D To my father, Asison De Silva Manikkuwahandi (1947-2019) Whose love, guide and encouragement day & night.…. Inspires me to go on adventures. ii ACKNOWLEDGEMENT This work is impossible without support and guidance from my advisor George Hornberger. Thank you, George, for believing me and accepting me as a PhD student. You are one among the few who make the world a better place. I am grateful for your guidance as my academic advisor as well as a second father throughout the graduate life. I would also thank to my research committee members – Hiba, Jonathan and Doug. Doug your generous offer to reach and speak is a great gift of the schooling time. It is a great opportunity to collaborate with Hiba and Jonathan for ADAPT- SL project and other studies. Your advices strengthen my studies present in this document. This work is supported by funding from National Science Foundation and Vanderbilt University. National Science Foundation Water, Sustainability and Climate program [Grant No EAR- 1204685] mainly supported for the work. Vanderbilt University supported part of the study and travel grants to participate the conferences where I got to know scientific community around the world. I would like to thank my friends and colleagues for their countless support. Thank you Asiri and Kishan from National Building Research Organization introducing me to ADAPT-SL Vanderbilt research team and support me to ascertain the PhD opportunity. Buddhika and my other Ceylon Electricity Board friends, without your support this might be impossible. I also offer my gratitude to Sunil Liyanagama and Mahaweli Authority staff for supporting me to complete this study. It would be a very hard task coming to US and going to school after 17 years without my Vanderbilt colleagues. Thanks to Emily, Thushara, Chelsea, Elizabeth, Mike, Josh, Paromita, Xiago, JinZhu, Saideep, CEE faculty & staff, and ISSS staff making my school life easy and happy. I treasure my memories with AAEES and ANS committee members and Jim Clarke. Also, my thanks go to Nashville Sri Lankan community being our new family to go through all those challenges. Last but certainly not least, I thank to my family for their love, support and being patience with me. I thank to my wonderful husband Muditha being with me this journey. My dear Nethmi, Sithmi and Devmi you always remind me what all those efforts are for. Thank you Amma (mom), Dilhan, Tharindu, Nadeesha and rest of the family for your love and support from Sri Lanka. I finally thank to you Thatta (dad) being the support, guide and strength of my life. iii TABLE OF CONTENTS Page DEDICATION…………………………………………………………………………………….2 ACKNOWLEDGEMENT ...............................................................................................................3 LIST OF FIGURES ...................................................................................................................... vii LIST OF TABLES ........................................................................................................................ xii LIST OF ACRONYMS .................................................................................................................xv Chapter 1 Introduction .............................................................................................................................1 1.1 Overview ................................................................................................................................ 1 1.2 Study Objectives .................................................................................................................... 3 2 Identifying ENSO Influences on Rainfall with Classification Models: Implications for Water Resource Management of Sri Lanka .......................................................................................6 2.1 Introduction ............................................................................................................................ 6 2.2 Hydrometeorology and Climatology of the Study Area ........................................................ 8 2.3 Sub-basin Rainfall (Areal Rainfall) ..................................................................................... 10 2.4 ENSO & IOD indices........................................................................................................... 11 2.5 Methods................................................................................................................................ 11 2.6 Quadratic Discriminant Analysis (QDA) ............................................................................. 12 2.7 Classification Tree Model .................................................................................................... 13 2.8 Random Forest ..................................................................................................................... 14 2.9 Results .................................................................................................................................. 16 2.10 Discussion ............................................................................................................................ 20 3 Assessing Water Management Alternatives in the Mahaweli Multipurpose Reservoir Cascade System ....................................................................................................................23 3.1 Introduction .......................................................................................................................... 23 3.2 Description of Reservoir Cascade ........................................................................................ 25 3.3 Methods................................................................................................................................ 29 iv 3.4 Simulation model ................................................................................................................. 29 3.4.1 Reservoir ...................................................................................................................... 29 3.4.2 Hydropower Plant ......................................................................................................... 30 3.4.3 Agricultural Systems .................................................................................................... 32 3.4.4 Water Distribution Decision ......................................................................................... 32 3.5 Project Performance Measurements .................................................................................... 34 3.5.1 Products of Water Users ............................................................................................... 34 3.5.2 Reliability, Resilience, and Vulnerability .................................................................... 34 3.5.3 Fraction of Water Utilization for Irrigation .................................................................. 36 3.6 Evaluation of Water Allocation Alternatives of Mahaweli Project ..................................... 36 3.7 Results .................................................................................................................................. 37 3.8 Discussion ............................................................................................................................ 42 4 Deriving Reservoir Cascade Operation Rules for Variable Stream Flows by Optimizing Hydropower Generation and Irrigation Water Delivery for the Mahaweli Project in Sri Lanka ...............................................................................................................................................45 4.1 Introduction .......................................................................................................................... 45 4.2 Methods................................................................................................................................ 46 4.3 Synthetic Stream Flow Generation ...................................................................................... 48 4.4 Reservoir Cascade Operation Policy Optimization ............................................................. 50 4.5 Multiple Objectives in Optimization ................................................................................... 51 4.5.1 Hydropower Energy ..................................................................................................... 51 4.5.2 Agricultural Yield ......................................................................................................... 52 4.5.3 Formulating Objectives in Optimization ...................................................................... 53 4.5.4 Multi-Objective Evolutionary Algorithm ..................................................................... 54 4.6 Results .................................................................................................................................. 55 4.7 Discussion ...........................................................................................................................