University of Central Florida STARS Electronic Theses and Dissertations, 2004-2019 2012 Risk Management In Reservoir Operations In The Context Of Undefined Competitive Consumption Yunus Salami University of Central Florida Part of the Civil Engineering Commons Find similar works at: https://stars.library.ucf.edu/etd University of Central Florida Libraries http://library.ucf.edu This Doctoral Dissertation (Open Access) is brought to you for free and open access by STARS. It has been accepted for inclusion in Electronic Theses and Dissertations, 2004-2019 by an authorized administrator of STARS. For more information, please contact [email protected]. STARS Citation Salami, Yunus, "Risk Management In Reservoir Operations In The Context Of Undefined Competitive Consumption" (2012). Electronic Theses and Dissertations, 2004-2019. 2381. https://stars.library.ucf.edu/etd/2381 RISK MANAGEMENT IN RESERVOIR OPERATIONS IN THE CONTEXT OF UNDEFINED COMPETITIVE CONSUMPTION by YUNUS DADA SALAMI B.S. University of Ilorin, Ilorin, 2002 M.S. Marquette University, 2007 A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Civil and Environmental Engineering in the College of Engineering and Computer Science at the University of Central Florida Orlando, Florida Fall Term 2012 Major Professor: Fidelia N. Nnadi © 2012 Yunus Salami ii ABSTRACT Dams and reservoirs with multiple purposes require effective management to fully realize their purposes and maximize efficiency. For instance, a reservoir intended mainly for the purposes of flood control and hydropower generation may result in a system with primary objectives that conflict with each other. This is because higher hydraulic heads are required to achieve the hydropower generation objective while relatively lower reservoir levels are required to fulfill flood control objectives. Protracted imbalances between these two could increase the susceptibility of the system to risks of water shortage or flood, depending on inflow volumes and operational policy effectiveness. The magnitudes of these risks can become even more pronounced when upstream use of the river is unregulated and uncoordinated so that upstream consumptions and releases are arbitrary. As a result, safe operational practices and risk management alternatives must be structured after an improved understanding of historical and anticipated inflows, actual and speculative upstream uses, and the overall hydrology of catchments upstream of the reservoir. One of such systems with an almost yearly occurrence of floods and shortages due to both natural and anthropogenic factors is the dual reservoir system of Kainji and Jebba in Nigeria. To analyze and manage these risks, a methodology that combines a stochastic and deterministic approach was employed. Using methods outlined by Box and Jenkins (1976), autoregressive integrated moving average (ARIMA) models were developed for forecasting Niger river inflows at Kainji reservoir based on twenty-seven-year-long historical inflow data (1970-1996). These were then validated using seven-year inflow records (1997-2003). The model with the best correlation was a seasonal multiplicative ARIMA (2,1,1)x(2,1,2)12 model. Supplementary iii validation of this model was done with discharge rating curves developed for the inlet of the reservoir using in situ inflows and satellite altimetry data. By comparing net inflow volumes with storage deficit, flood and shortage risk factors at the reservoir were determined based on (a) actual inflows, (b) forecasted inflows (up to 2015), and (c) simulated scenarios depicting undefined competitive upstream consumption. Calculated high- risk years matched actual flood years again suggesting the reliability of the model. Monte Carlo simulations were then used to prescribe safe outflows and storage allocations in order to reduce futuristic risk factors. The theoretical safety levels achieved indicated risk factors below threshold values and showed that this methodology is a powerful tool for estimating and managing flood and shortage risks in reservoirs with undefined competitive upstream consumption. iv ACKNOWLEDGMENTS My deepest gratitude goes first to my parents who through the years have always willingly provided me with material and moral support, the former whenever they were able, the latter always. Their encouragement throughout my educational career has been immeasurable and despite being physically away from them during my doctoral studies, I could never have achieved this without them. I wish to thank my advisor Dr. Fidelia Nnadi for her dual role as a professional mentor and a guardian of sorts. Her timely, generous, and valuable feedback and her talent for mixing praise with constructive criticism instilled resilience in me and increased my overall motivation as a student, a teacher, a researcher and an engineer. I am also grateful to my dissertation committee: Dr. Wang, Dr. Rowney, Dr. Divo, and Dr. Chopra for making out time out of their busy schedules to provide advice and sit on my PhD proposal and final defense committees. Special thanks go to my friends and siblings for their encouragement and their prescriptions of the twin panaceas of “faith and patience”. v TABLE OF CONTENTS LIST OF FIGURES ........................................................................................................... xi LIST OF TABLES ........................................................................................................... xvi CHAPTER 1: INTRODUCTION ....................................................................................... 1 1.1 Risk Management Considerations. ............................................................................ 2 1.2 Shortage Risk Consideration. .................................................................................... 3 1.3 Flood Risk Consideration. ......................................................................................... 4 1.4 Flood risks and innovations in reservoir operations and monitoring ........................ 6 1.5 Problem Statement and Objective of Research. ........................................................ 7 1.6 Goals and Objectives ................................................................................................. 8 1.6.1 Goal ................................................................................................................. 8 1.6.2 Objectives ........................................................................................................ 8 CHAPTER 2: ANALYSIS OF RIVER DISCHARGE AND HYDROLOGICAL CLASSIFICATION OF RIVER BASIN CATCHMENTS .................................. 10 2.1 Introduction. ............................................................................................................ 10 2.2 Background and Study Area ................................................................................... 11 2.2.1 The Niger River Basin................................................................................... 11 2.2.2 Kainji Reservoir and Jebba Reservoirs ......................................................... 14 2.3 Water Management at the Kainji reservoir ............................................................. 22 2.3.1 Overall Reservoir Management .................................................................... 22 2.3.2 Flood Events .................................................................................................. 23 2.4 Methodology and Data Collection .......................................................................... 25 vi 2.4.1 Stream discharge ........................................................................................... 25 2.4.2 Water Level Measurement ............................................................................ 26 2.4.3 Pre-modeling considerations ......................................................................... 27 2.5 Results and Discussion ............................................................................................ 29 2.6 Conclusions ............................................................................................................. 34 CHAPTER 3: STOCHASTIC MODELING OF RESERVOIR INFLOWS .................... 36 3.1 Introduction ............................................................................................................. 36 3.2 Background and Data Collection ............................................................................ 37 3.2.1 Previous Case Studies .................................................................................. 37 3.3 Preliminary Considerations for Time Series Modeling of Inflows ......................... 40 3.4 Climate Change Considerations .............................................................................. 41 3.4.1 Stochastic Methods and Time Series Modeling ............................................ 42 3.5 Fundamentals of Box and Jenkins Modeling .......................................................... 43 3.6 Methodology ........................................................................................................... 45 3.6.1 Seasonal Multiplicative Model...................................................................... 46 3.6.2 Diagnostic Checking ..................................................................................... 48 3.6.3 The Ljung–Box test ....................................................................................... 48 3.7 Results