Environmental and Social Impact Assessment - Gibe III

Gibe III – Environmental and Social Impact Assessment 300 ENV R CS 002 C – A9003099
List of Tables
Table 0.1: Summary of Project Impact on Household Assets by Wereda and Project Component .......... 18
Table 0.2: Summary of estimated environmental mitigation, monitoring and training costs.................... 27
Table 3.1: Geometrical characteristics of the diversion tunnels................................................................ 53
Table 3.2: Spillway chute hydraulic analysis ............................................................................................ 57
Table 3.3: Middle Level Outlet – Hydraulic calculations main result....................................................... 58
Table 4.1: Flow chart of the Environmental Impact Assessment of a project........................................... 71
Table 4.2: Synthesis of Environment Impact Matrix................................................................................. 74
Table 5.1: Maximum monthly temperatures (°C)...................................................................................... 76
Table 5.2: Minimum monthly temperatures (°C) ...................................................................................... 76
Table 5.3: Mean monthly temperatures (°C) ............................................................................................. 76
Table 5.4: Mean monthly rainfall (mm) .................................................................................................... 77
Table 5.5: Mean monthly ETP (mm)......................................................................................................... 77
Table 5.6: Comparison between Mean monthly rainfall and ETP at dam site (mm) ................................ 77
Table 5.7: Description, according to FAO classification, of the soils identified in the reservoir area...... 92
Table 5.8: Physical data of the watersheds................................................................................................ 96
Table 5.9: Rainfall stations of the NMSA and periods of observation...................................................... 99
Table 5.10: Mean monthly and yearly rainfall for the all the considered gauging stations....................... 100
Table 5.11: Runoff stations of the EWRA and periods of observation ..................................................... 102
Table 5.12: Mean runoff estimated at dam site ......................................................................................... 106
Table 5.13: Monthly variability of runoff at Dam Site 5 in m 3 /s............................................................... 107
Table 5.14: Monthly variability of runoff at Dam Site 5 in Mm 3 .............................................................. 107
Table 5.15: Total annual and mean monthly runoff at Dam Site 5 in Mm 3 .............................................. 107
Table 5.16: Frequency Analysis – Growth Factors and Point Rainfall of Gibe III ................................... 109
Table 5.17: Point PMP within the project area.......................................................................................... 110
Table 5.18: Gibe III catchment – Areal Reduction Factors....................................................................... 111
Table 5.19: Gibe III catchment – Weiss correction factors ....................................................................... 111
Table 5.20: Gibe III Areal Rainfall Depths ............................................................................................... 112
Table 5.21: Gibe III Basin – 360 hrs (15 days) Design Hyetographs........................................................ 114
Table 5.22: Gibe III HMS model – CN values.......................................................................................... 114
Table 5.23: Gibe III HMS model – Tlag values ........................................................................................ 115
Table 5.24: Gibe III HMS Model – 10,000 yr Analysis Main Results...................................................... 116
Table 5.25: Gibe III HMS Model – PMF Analysis Main Results ............................................................. 116
Table 5.26: Gibe III Dam Site – Extreme Flood Hydrographs.................................................................. 117
Table 5.27: Comparison with Other Hydrologic Studies .......................................................................... 119
Table 5.28: Results of chemical analysis................................................................................................... 121
Table 5.29: Comparison table between two different sampling campain (2004 and 2006) at the same place
................................................................................................................................................ 122
Table 5.30: Land Cover Distribution in the Gibe III Reservoir Area........................................................ 124
Table 5.31: The species composition of Terraces III and IV .................................................................... 129
Table 5.32: Riparian macro-invertebrates at the Omo bridge ................................................................... 130
Table 5.33: Habitat integrity rating for the Omo dam site downstream.................................................... 131
Table 5.34: Habitat integrity rating for the Omo bridge site ..................................................................... 132
Table 5.35: Population of the Affected Weredas and Peasant Association (2006) ................................... 139
Table 5.36: Ethnic Composition by Wereda in the Project Area............................................................... 140
Table 5.37: Population of the Weredas by Type of Religion in Percentage.............................................. 140
Table 5.38: Livestock Population of the Affected Weredas...................................................................... 145
Table 5.39: Ten Top Diseases, 2004/05 .................................................................................................... 152
Table 5.40: Health Coverage of the Affected Weredas............................................................................. 153
Table 5.41: Health Institutions and Personnel in the Weredas.................................................................. 153
Table 5.42: Water Supply Coverage of the Affected Weredas (in %) ...................................................... 154
Table 5.43: NGOs working in the affected Wereda .................................................................................. 155
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