Akosombo Dam.pptx

dam

1. LOCATION OF AKOSOMBO DAM Located at Volta river in south-eastern Ghana on Volta river Basin.

2. HISTORY The building of the Akosombo dam follows almost a period of two decades of planning which began in 1947 when the first feasibility studies were conducted on the potential for Volta river as a hydropower source.  The actual construction of the dam took place within1962-1972 under the management of the Volta River Authority (VRA) . Jointly financed by  government of Ghana, the World Bank, the United States, and the United Kingdom.   There were three phases of the project, phase one was the installation of 588MW unit of electricity which was completed in 1966m. The second phase involved an addition of 304MW electricity which resulted in total of 912 MW at the Akosombo dam. The last phase of the project was the setting up of a smaller HEP dam, 21km downstream, at Kpong

3. DESIGN Height: 114 m Base Width: 366 m Length : 660 m Structural Volume : 7,991,000 m 3 Rock-fill Embankment Dam Dam impounds the lake Volta received the flows from three rivers Oti, Black Volta and White Volta and discharges into the lower Volta river and then the Atlantic Ocean The reservoir, Lake Volta, is the largest man-made lake in the world by surface area (8502 m 2 ) with a volume of 148 km 3 at its peak of 278 feet. Consists of six 230,000 hp Francis turbines which are supplied with water via a 112–116 m long and 7.2 m diameter penstock with a maximum of 68.8 m of hydraulic head afforded. A total of 1072MW of electricity is generated by the Akosombo HEP as per VRA, 2010.

4. OBJECTIVE  To make VALCO (Volta Aluminum Company) energy sufficient so that its activity which is mainly aluminum smelting would be proceed without interruption.  To supply electricity for both domestic and industrial use and also export to the basin sharing countries (Benin and Togo). To provide opportunities for large-scale irrigation, modernization of agriculture, promotion of factories and industries, and the establishment of tourist facilities.

5. SOCIO-ECONOMIC BENEFITS The Akosombo HEP provides over 85% of all electricity generated in Ghana leads to economic and industrial development in Ghana.  Ghana’s economy is twice the average of the West African sub region The creation of the Volta Lake led to increase in fishing stock  Farming activities is also intensified along the 5500 km shoreline especially locations downstream of the lake as a result of water availability for the purposes of irrigation. Navigation on the Volta river has changed significantly serving as a mean for transportation for goods. The direct tourism impact resulting from the lake includes opening up part of hitherto inaccessible attractions to both local and international travellers.

6. EFFECT ON ECOLOGY There has been a steady decline in agricultural productivity along the lake and the associated tributaries. Downstream agricultural systems are losing soil fertility without the periodic flooding that brought nutrients to the soil before the natural river flow was halted by the dam. The land surrounding Lake Volta is not nearly as fertile as the formerly cultivated land residing underneath the lake. Heavy agricultural activity has exhausted the already because of inadequate soils. The growth of commercially intensive agriculture has produced a rise in fertilizer run-off into the river leads to eutrophication of the river waters. The nutrient enrichment, in combination with the low water movement, has allowed for the invasion of aquatic weeds which creates a formidable challenge to water navigation and transportation

7. CHALLENGES ON SOCIAL ACTIVITY Displacement of 80,000 people across 700 villages in low lying areas and resettle them into 52 new villages lead to the lost of the original communities resulted in many socio-physiological problems in the communities. The Volta lake creation leads to a loss of 3.6% of the total land surface of Ghana including forest land to the reservoir.  As a result of less arable land to farm the men switch to fishing while most of the women were involved in prostitution as a profession to satisfy the male workers whom were building the dam..   For fish and other aquatic biota, due to the ability of the dam to alter or blocking the migration resulting in genetic disconnect between species population. Injustice to the communities upstream and downstream is that it took three decades to be connected to the national electricity grids.

8. CHALLENGES ON ECONOMIC ACTIVITY The upstream communities and downstream communities are among the poorest in the country lacking access to basic necessities like hospital, roads, proper sanitation and water facilities. The lost land lead to decline in the primary economic activities of crop and livestock farming for most of the communities both downstream and upstream of the dam. The extensive human migration and degradation of natural resources within the Volta-basin area, are the products of poverty in conjunction with population pressure. the rural and industrial economies have experienced the financial losses associated with the decimation of river aquaculture.

9. IMPACT ON HUMAN WALFARE The presence of aquatic weeds provide the necessary habitat for black-fly, mosquitoes and snails, which are the vectors of water-borne illnesses such as bilharzia ( 2% to 32% at downstream and 0.5% to 27.4% in upstream), river blindness and malaria (increased by an average of 10% both upstream and downstream ). Children and fishermen have been especially hard hit by this rise of disease prevalence. This migration enabled the contraction of HIV and has since led to its heightened prevalence within Volta Basin communities

10. IMPACT ON GEOLOGY Increase in seismic activities (4 major earthquakes of magnitude 5 or higher have been recorded in the area) around the dam since the construction of the lake. Believing that  earthquakes are due to the overloading of the geological bedrock underlying the lake with which is triggering the active Akwapim fault. Sediments load have decrease by about 60mg/l downstream of the dam as a result of the impoundment. The lack of sediment has lead to the erosion of the coastline in the neighbouring Togo and Benin at a rate of 10-15m/y. Morphology of the delta have shifted 12 km eastward from the original lower Volta entre point to the sea leading to coastal erosion at Ada. In accordance with the behaviour of tropical dam microclimate the temperature and rainfall in the south eastern part of Ghana is higher than the average in other parts of the basin.

11. CONTROVERSIES