ADDIS ABABA UNIVERSITY ADDIS ABABA INSTITIUTE OF TECHNOLOGY SCHOOL OF GRADUATE STUDIES WATER USE AND OPERATION ANALYSIS OF WATER RESOURCE SYSTEMS IN OMO GIBE RIVER BASIN M.Sc. Thesis Daniel Asefa May 2011 Addis Ababa ADDIS ABABA UNIVERSITY ADDIS ABABA INSTITIUTE OF TECHNOLOGY SCHOOL OF GRADUATE STUDIES Water Use and Operation Analysis of Water Resource Systems in Omo Gibe River Basin Submitted in partial fulfillment for the Degree of Masters of Science in Civil Engineering (Major in Hydraulic Engineering) By Daniel Asefa Addis Ababa May 2011 Declaration and Copyright I, Daniel Asefa Alene, declare that this is my own original work and that it has not been presented and will not be presented to any other University for similar or any degree award. ___________________________ Signature This dissertation is a copyright material protected under the Berne Convention, the Copyright Act, 1999 and other international and national enactments in the behalf, on the intellectual property. It may not be produced by any means in full or in part, except for short extracts in fair dealing, for research or private study, Critical scholarly review or disclosure with an acknowledgement, without written permission of the School of Graduate Studies, on the behalf of both the author and the Addis Ababa University I Acknowledgement My deep appreciation goes to my advisor Dr.In.Dereje Hailu of Addis Ababa University for his encouragement, advice, support and, his valuable guidance and lectures throughout the course of this study and, above all his unselfish contribution to this thesis. His trust and confidence makes me to work on my interest topic. I would like to acknowledge the Ethiopian Electric Power Corporation (EEPCO) particularly Ato Daniel; Ministry of Water and Energy Resource MoWE particularly hydrology and hydropower department, GIS department and Library, for their appreciable support in providing me hydrological data and other reference materials; and the Ethiopia Meteorological Service Agency for providing me the relevant data and information required free of charge. My deepest thank is to my beloved parents. Their unconditional love, inspiration and encouragement always surround me, support me, and give me strength to go through my study. A special group of friends also supported me through their friendship and professional help. Among them I would like to mention: Abdrhaman B., Ahmed A., Abayne A., Bogale T. and Biruk A Above all, sincere thanks go to the Almighty God and his mother saint Virgin Mary for making this thesis success. This day God what you have done for me is really beyond what I can imagine and I have dreamt. Indeed, thanks for everything You have been doing for me. II Abstract In this study, HEC-ResSim (Hydrologic Engineering Center-Reservoir System Simulation) model was used to simulate water use and operation of existing, ongoing and planned hydraulic infrastructures, and irrigation schemes in Omo Gibe river basin. For these purpose five different water resource scenarios were simulated viz. Scenario-T, Scenario-A, Scenario-B, Scenario-C and Scenario-D. Scenario-T was first set up to simulate gauged flow routing without taking into account effects of development and a good agreement was observed between simulated and measured flow at Karadus station. The Nash-Sutcliffe efficiency criterion obtained for the catchment was 0.782. Following this, the model was configured to simulate the recent and proposed development interventions on water resource. Scenario-A result showed that an average annual energy of 780GWh/year and 1911GWh/year are produced by Gibe I and Gibe II respectively when they are operated in tandem. Equivalent storage distribution was also examined among reservoirs in the entire simulation period. The current study, HEC-ResSim simulation in scenario B, has discovered that long term effects of operation of Gibe III power plant would increase the dry season outflow and decrease in flood season outflow from the Omo- Gibe river system. An average increase of 130% in mean monthly inflows from November to June and decrease of 25% in mean monthly inflows from July to October was observed at Karadus. But the mean annual outflow from the basin at Karadus will be decrease by 1.14%. Simulation of Gibe III power plant produced an average annual energy of 6,488GWh/year and power of 758.94MW.The firm energy and power that can be guaranteed 90% of the time are 5885GWh/year, 625.0MW respectively. The average energy obtained is close with the study made by EEPCO. The firm energy obtained is also similar and greater than the energy obtained during reservoir operation studied by EEPCO. Due to upstream regulation i.e. intervention the proposed power plants, Gojeb and Hallele Warabesa stage I and II, in the upstream Omo-Gibe basin under scenario D can increases firm energy production of Gibe III power plant to 6023GWh (2.75%) per year with same reliability and the average annual energy can also increase to 7587 GWh per year (by 15.66%). Moreover, during scenario D simulation annually about 1.87BCM volume of water will be diverted into irrigation site under full irrigation development (142,000ha) and the annual volume of water from Omo-Gibe river system below the proposed irrigation sits will decrease by 14.15%. Keywords: Firm Energy, HEC-ResSIM, Reservoir Operation, Simulation scenario, Karadus, and Reservoir Network III Dedication This work is dedicated solely to my mother Abeba Yemataw, my aunt Messeret and uncle Sisay IV Table of Contents Declaration and Copyright ........................................................................................................................ I Acknowledgement .................................................................................................................................... II Abstract ................................................................................................................................................... III Dedication .............................................................................................................................................. IV Table of Contents ..................................................................................................................................... V List of figures ....................................................................................................................................... VIII List of tables ............................................................................................................................................. X 1.0 INTRODUCTION .............................................................................................................. 1 1.1 Background ......................................................................................................................................... 1 1.2 Problem Statement .............................................................................................................................. 3 1.4 Objectives of the study ........................................................................................................................ 4 1.5 Structure of the Thesis ......................................................................................................................... 4 2.0 LITREATURE REVIEW .................................................................................................. 6 2.1 Technologies for Decision Making in Water Management................................................................. 6 2.2 Reservoir/River System modeling ....................................................................................................... 7 2.2.1 General ............................................................................................................................................. 7 2.2.2 Simulation ........................................................................................................................................ 8 2.2.3 Optimization ..................................................................................................................................... 9 2.4 Review of river basin simulation models ............................................................................................ 9 2.4.1General .............................................................................................................................................. 9 2.5 Introducing HEC-ResSim.................................................................................................................. 12 2.5.1 HEC-ResSim Environment for Model Building ............................................................................ 13 2.6 Reservoir Operation Rules ................................................................................................................ 15 2.6.1 Reservoir Operation rule in HEC-ResSim ..................................................................................... 17 2.6.2 Tandem operation rule in HEC ResSim ......................................................................................... 18 2.6.3 Implicit and Explicit system storage balance ................................................................................. 18 2.7 Previous Studies in the Basin ............................................................................................................ 19 2.7.1 Omo-Gibe river basin Integrated development master plan Study ...............................................