1. Survey of Existing Dams 1.096 Environmental Engineering Clinic Week 2 - February 13, 2004 Teresa Yamana

2. Objective To gain insight into our assessment of the Merowe Dam in the areas of: –Sedimentation –Small Scale Impacts Archeology Public Health Resettlement

3. Three Gorges Dam, China - Yangtze River www.cbc.ca/news/features/threegorges_quickfacts.html

4. Dam Overview Purpose –Flood prevention –Power generation Cost: $24.7 billion Expected Completion: 2009 Height: 175 m Reservoir –Area: 1080 km 2 –Volume: 39.3 bcm Power Capacity: 18,200MW

5. 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%

6. Downstream Effect of Sedimentation Erosion of riverbed, leading to decrease in water level between 0.5 - 8.0m Requires minimum 5000 m 3 /s discharge at Yichang shiplock Caving banks Shallow bendways impede local navigation Mitigate damage of flood and waterlogging in Dongting Lake area

7. Small Scale Impacts 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

8. Aswan Dam, Egypt - Nile River www.usgs.gov/features/ satellite_images.html

9. Dam Overview Purpose –Flood prevention –Power generation Cost: $1 billion Completed: 1970 Height: 111 m Reservoir –Area: 6000 km 2 –Volume: 169 bcm Power Capacity: 21,000 MW

10. 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

11. Small Scale Impacts Archeology –Twin temples of Pharoah Ramses II relocated by UNESCO UNESCO Courier, Dec. 1964. http://www.pbs.org/wgbh/nova/

12. 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

13. Tarbela Dam - Indus River, Pakistan www.dams.org www.pakwapda.com/htmls/ water-dams.html

14. Dam Overview Purpose –Part of Indus Basin Irrigation System –Irrigation –Power generation Cost: $1.85 billion Completed:1993 Height: 148 m Reservoir –Area: 259 km 2 –Volume: 11.5 bcm Power Capacity: 3478 MW

15. 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

16. Small Scale Impacts Resettlement –120 villages submerged –96,000 people –Replacement land in Punjab or Sindh, or cash compensation for home –Widespread dissatisfaction

17. 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/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 Basin www.dams.org/kbase/studies/pk/pk_exec.htmwww.dams.org/kbase/studies/pk/pk_exec.htm –Pakistan Water and Power Development Authority http://www.pakwapda.com/htmls/water-dams.html