Water Management in the South Caucasus USAID Contract No. OUT-LAG-I-804-99-00017-00 FINAL REPORT Sedimentation of the Kura River In the South Caucasus Prepared for: U.S. Agency for International Development Mission for the South Caucasus Prepared by: Development Alternatives, Inc. Tblisi, Georgia October 2002 ________________________________________________________________________________________________________________ 83 Water Management in the South Caucasus November 9, 2002 Mr. Peter Argo Director Office of Energy & Environment U.S. Agency for International Development 20 Telavi Street, 5th Floor Tblisi 380003 Georgia Final Report Sedimentation of the Kura River Dear Mr. Argo, We are pleased to provide the USAID Caucasus Mission with the attached report titled Final Report on “Sedimentation of the Kura River in the South Caucasus ” for the project activities conducted to date in as part of the Water Management in the South Caucasus Project. This report is part of a series of activities for Water Resource Management in the Kura-Aras River Basin that address technical and related policy and institutional conditions and experiences relevant to achieving the objectives of the Project. This report summarizes some of the tasks completed as part of the Activity 1, Monitor Water Quantity and Quality in the Kura-Aras Basin. This report was prepared by the Dr. Gregory L. Morris with the cooperation of the Hydrometeorological Services in Armenia, Azerbaijan, and Georgia. This report is intended to be a focal point of discussions with the Hydrometeorological Services in each country to increase the dialogue for sustainable water management in the South Caucasus. The report provides detailed recommendations that will be considered for implementation. We are pleased to distribute this report to the interested parties in the region on behalf of USAID. Thank you for your assistance in support of this project. Sincerely, Paul C. Dreyer, PE Chief of Party Enclosure cc: Dr. Michael Boyd, USAID/Armenia Mr. William McKinney, USAID/Azerbaijan Mr. Edwin Stains, DAI/Bethesda D331 DCover83 14 Paliashvili Street, Tblisi 380079 Georgia AUA Center Building; 9 Alex Manukian Street, Suite 207; Yerevan 375070 Armenia Caspian Business Center; 40 Jafar Jabbarli Street, Suite 604; Baku 370000 Azerbaijan TABLE OF CONTENTS EXECUTIVE SUMMARY Introduction..................................................................................................................ii Reservoir Sedimentation and Loss of Water Supply .......................................................iii Sediment Problems Below Dams .................................................................................. iv Reservoirs and Water Quality in Kura River .................................................................. iv Recommendations for Sedimentation Problems Below Dams ........................................... v Recommendations for Sedimentation Problems Above Dams .......................................... v 1. INTRODUCTION................................................................................................................ 1 1.1. Scope and Purpose of Study .......................................................................................... 1 1.2. Sponsorship ................................................................................................................. 1 1.3. Limitations................................................................................................................... 2 2. STUDY AREA DESCRIPTION ............................................................................................ 2 2.1. Study Area Location ..................................................................................................... 2 2.2. Climate........................................................................................................................ 2 2.3. Kura River ................................................................................................................... 3 2.4. Reservoirs Along Kura River ......................................................................................... 5 3. EROSION AND SEDIMENT YIELD.................................................................................... 5 3.1. Methods....................................................................................................................... 5 3.2. Erosion Conditions in Georgia....................................................................................... 6 3.3. Sediment Yield from Kura Basin in Georgia................................................................... 6 3.4. Erosion Conditions in Azerbaijan .................................................................................. 7 4. RESERVOIR OPERATIONS................................................................................................ 8 4.1. Services Provided and Service Area ............................................................................... 8 4.2. Reservoir Inflow and Discharge..................................................................................... 9 4.3. Reservoir Level .......................................................................................................... 10 4.4. Reservoir Operation and Kura Flow............................................................................. 10 5. WATER QUALITY................................................................................................................ 11 5.1. Water Quality Data..................................................................................................... 11 5.2. Reservoirs and Water Quality ...................................................................................... 14 5.3. Water Quality and Reservoir Stratification ................................................................... 15 6. SEDIMENTS AND SUSTAINABLE USE ........................................................................... 16 6.1. Sedimentation and Reservoir Life ................................................................................ 16 6.2. Reservoir Bathymetric Data ........................................................................................ 16 6.3. Bed Material Sediment Data........................................................................................ 16 6.4. Sediment Trap Efficiency ............................................................................................ 17 6.5. Suspended Sediment Data........................................................................................... 17 6.6. Trends in Suspended Sediment Yield ........................................................................... 18 6.7. Reservoir Half-Life..................................................................................................... 19 7. APPENDICES ................................................................................................................... 20 i SEDIMENTATION OF KURA RIVER BASIN IN THE SOUTH CAUCASUS EXECUTIVE SUMMARY Introduction Azerbaijan has 135 reservoirs with over 0.5 million cubic meters of storage capacity, many of these located within the Kura River Basin. Of the 21.6 km3 of reservoir storage nationwide, 85% (18.4 km3) is contained in three reservoirs on the Kura River as shown in Table E1. These three reservoirs are located one after the other, with Mingechevir Reservoir being the most downstream. Table E1: Summary of Reservoirs on Main Stem of Kura River. Maximum Original Hydropower Name Year Built Irrigation Water Level, m Capacity Mm3 Capacity, MW Varvara 1956 18 60 16.5 Yes Mingechevir 1953 83 16,600 380 a/ Yes Enikend 1998 104 158 150 No Shamkir 1980 158 2,677 370 Yes Totals 19,495 816.5 Abbreviations: Mm3 = million cubic meters, MW = megawatt, a/ Enlargement from 360 to 380 MW capacity under construction. Azerbaijan has approximately 1.4 million hectares under irrigation and its agricultural economy depends heavily on reservoirs, with Minge chevir alone irrigating about half the total area. There are no reservoirs on the main stem of the Kura River in Georgia, although hydropower reservoirs exist on some tributaries, and considerable unexploited hydropower potential exists in Georgia. Reservoirs strongly affect both hydrologic conditions and the sediment balance along the river system below the dam. The river downstream is deprived of sediments, promoting erosion and degradation of the river bed. On the other hand, elimination of flood flows by the reservoir can cause sediments to accumulate. An important example of this has occurred at the mouth of the Kura River, formerly about 4 meters deep, which is now reportedly only 0.5 to 1.0 meters deep because of sediment accumulation. Because of flow regulation and irrigation diversions, annual floods no longer scour sediment from the river mouth. The resulting shallow water and river mouth bar impede sturgeon from entering the river. ii Reservoir Sedimentation and Loss of Water Supply The useful life of large reservoirs is generally limited by the rate of sediment accumulation. In large reservoirs, such as those on the Kura River, the volume of sediment that will accumulate is so great that removal is not feasible. As a rough rule of thumb, reservoir operations will become seriously affected when half of the volume has become sedimented. To maintain the long-term functioning of this nationally important water supply infrastructure, it is necessary to determine appropriate strategies for dealing with sedimentation.