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Survey of Existing Dams 1.096 Environmental Engineering Clinic Week 2 - February 13, 2004 Teresa Yamana Objective To gain insight into our assessment of the Merowe Dam in the areas of: Sedimentation Small Scale Impacts Archeology Public Health Resettlement
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Survey of Existing Dams 1.096 Environmental Engineering Clinic Week 2 - February 13, 2004 Teresa Yamana
Objective • To gain insight into our assessment of the Merowe Dam in the areas of: • Sedimentation • Small Scale Impacts • Archeology • Public Health • Resettlement
Three Gorges Dam, China - Yangtze River www.cbc.ca/news/features/threegorges_quickfacts.html
Purpose Flood prevention Power generation Cost: $24.7 billion Expected Completion: 2009 Height: 175 m Reservoir Area: 1080 km2 Volume: 39.3 bcm Power Capacity: 18,200MW Dam Overview
Sedimentation in Reservoir • 40 year sedimentation observation data • Store clean water during dry season, sluice muddy water in flood season • Scouring and silting to reach balance • Initial sediment discharge rate 30-40% • Storage remaining after 100 years • Flood storage: 86% • Regulated storage: 92%
Downstream Effect of Sedimentation • Erosion of riverbed, leading to decrease in water level between 0.5 - 8.0m • Requires minimum 5000 m3/s discharge at Yichang shiplock • Caving banks • Shallow bendways impede local navigation • Mitigate damage of flood and waterlogging in Dongting Lake area
Archeology 1300 Archeological sites to be submerged Cultural relics from various dynasties 200 ancient tombs International effort to excavate Public Health Unlikely increase in schistosomiasis Likely increase in malaria, other local water related diseases Resettlement 844,124 residents Relocate 130 villages Small Scale Impacts
Aswan Dam, Egypt - Nile River www.usgs.gov/features/ satellite_images.html
Purpose Flood prevention Power generation Cost: $1 billion Completed: 1970 Height: 111 m Reservoir Area: 6000 km2 Volume: 169 bcm Power Capacity: 21,000 MW Dam Overview
Sedimentation in Reservoir • Majority of sediment inflow trapped in tail end of reservoir • Dead storage capacity of 31.6 bcm for 500 years • Feasibility study being conducted for uses of sediments • Lack of sediments downstream means farmers use 13,000 t fertilizer
Small Scale Impacts http://www.pbs.org/wgbh/nova/ UNESCO Courier, Dec. 1964. • Archeology • Twin temples of Pharoah Ramses II relocated by UNESCO
Small Scale Impacts • Public Health • Schistosomiasis associated with stagnant water from Dam • Resettlement • 90,000 Nubians displaced • In Egypt, 28 miles away • In Sudan, 370 miles away
Tarbela Dam - Indus River, Pakistan www.pakwapda.com/htmls/ water-dams.html www.dams.org
Purpose Part of Indus Basin Irrigation System Irrigation Power generation Cost: $1.85 billion Completed:1993 Height: 148 m Reservoir Area: 259 km2 Volume: 11.5 bcm Power Capacity: 3478 MW Dam Overview
Sedimentation in Reservoir • Sediment inflow 0.106 bcm/yr • Useful life 85 years • Concern about sediments blocking power intakes in case of earthquake • Underwater protection to low-level outlets • Sediment management • Sluicing tunnels to remove sediment • Management measures to reduce sediment deposition • Not feasible to reduce sediment inflow
Small Scale Impacts • Resettlement • 120 villages submerged • 96,000 people • Replacement land in Punjab or Sindh, or cash compensation for home • Widespread dissatisfaction
References • Three Gorges Dam • Chinese Academy of Sciences and the Research Inst. For Protection of Yangtze Water Resources. Environmental Impact Statement for the Yangtze Three Gorges Project • Nova. Damming the Past www.pbs.org/wgbh/nova/zeugma/ • Aswan High Dam • Marc Lavergne. The Seven Deadly Sins of Egypt’s Aswan High Dam • Asit K. Biswas. Aswan Dam Revisited • Hassan Osman. Hydro Development in Egypt - Lessons from High Aswan Dam • The Aswan High Dam http://geography.about.com/library/weekly/aa012698.htm • Tarbela Dam • World Commision on Dams. Pakistan: The Tarbela Dam and Indus River Basinwww.dams.org/kbase/studies/pk/pk_exec.htm • Pakistan Water and Power Development Authority http://www.pakwapda.com/htmls/water-dams.html