Akosombo Hydro Plant

The Akosombo Dam, also known as the Volta Dam, is a hydroelectric dam on the Volta River in the Akosombo Gorge in southeastern Ghana. The Volta River Authority operates it. The dam’s construction inundated part of the Volta River Basin, resulting in the formation of Lake Volta. By surface area, Lake Volta is the world’s largest man-made lake. It spans 8,502 square kilometers (3,283 square miles), accounting for 3.6 percent of Ghana’s total land area. Lake Volta is the world’s third largest man-made lake by volume, with a volume of 148 cubic kilometers. The largest, Lake Kariba, has a volume of 185 cubic kilometers.

The Akosombo Dam was built primarily to supply electricity to the aluminum industry. “The largest single investment in Ghana’s economic development ambitions,” according to the Akosombo Dam. The dam is particularly important since it provides the majority of Togo’s and Benin’s power. However, the Adjarala Dam (on Togo’s Mono River) is intended to lessen these countries’ reliance on imported electricity. The dam’s original electrical output was 912 megawatts (1,223,000 horsepower), but a refit project completed in 2006 increased it to 1,020 megawatts (1,370,000 horsepower).

Many people were displaced by the flooding that produced the Lake Volta reservoir, which had a considerable influence on the local ecosystem, including seismic activity that caused coastal erosion; changing hydrology caused microclimatic changes, with less rain and higher temperatures. The soil around the lake is less fertile than the soil beneath it, and heavy agricultural use has necessitated the use of fertilizers, resulting in eutrophication, which has resulted in the explosive growth of an invasive weed that makes water navigation and transportation difficult, as well as providing a habitat for vectors of water-borne illnesses like bilharzia, river blindness, and malaria. The displaced people’s resettlement was difficult and, in some cases, futile; traditional farming traditions vanished, and poverty intensified.

History

Although geologist Albert Ernest Kitson proposed the dam in 1915, no blueprints were prepared until the 1940s. The Volta River Basin was suggested for development in 1949, but due to a lack of funds, the American corporation Volta Aluminum Company (Valco) lent money to Ghana so that the dam could be built. The Volta River hydroelectric project was adopted by Kwame Nkrumah.

The final project called for the construction of an aluminum smelter in Tema, a dam in Akosombo to supply power to the smelting, and a network of power lines across southern Ghana. The aluminum smelter was projected to generate enough income to start local bauxite mining and processing, allowing aluminum manufacturing to be done without importing foreign alumina. The anticipated hydroelectric power was critical to the development of Ghana’s aluminum industry. The aluminum smelter for the proposed project was designed by Kaiser Aluminum and is operated by Valco. Valco shareholders contributed money to the smelter, which was backed by the Export-Import Bank of Washington, DC. On the other hand, Valco did not invest without first obtaining insurance from Ghana’s government, such as firm exemptions from trade taxes and reduced electricity purchases. The total cost of the project was anticipated to be $258 million.

The Ghana government issued a tender for the building of the hydroelectric dam in May 1960. The contract was awarded in 1961 to Impregilo, an Italian company that had recently constructed the Kariba Dam. Despite flooding of the Volta River in 1963, which delayed work for three months, they completed the dredging of the river bed and dewatering of the channel and built the dam a month ahead of schedule. During the construction of the dam, 28 Impregilo workers died between 1961 and 1966. In their honor, memorials have been erected in Akosombo township and at St. Barbara Catholic Church.

Ghana’s Parliament formed the Volta River Authority (VRA) in 1961 with the passing of the Volta River Development Act. Six board members and Kwame Nkrumah as chairman established the VRA’s basic functions. The VRA’s main responsibility is to oversee the development of the Volta River Basin, including the building and monitoring of the dam, power station, and transmission network. The VRA is in charge of the dam-dammed reservoir, lake fishing, lake transit and communication, and the welfare of persons who live near the lake.

Between 1961 and 1965, the dam was constructed. It was developed by the Ghanaian government with 25% funding from the World Bank’s International Bank for Reconstruction and Development, the United States, and the United Kingdom.

The Akosombo dam flooded part of the Volta River Basin and its upstream areas, resulting in the formation of Lake Volta an area that now spans 3.6 percent of Ghana’s total geographical area. Between 1962 and 1966, Lake Volta was built, requiring the migration of approximately 80,000 people, or about 1% of the population. The VRA oversaw the relocation of 700 people from 700 villages into 52 resettlement villages two years before the lake was completed. Riparian fishermen made up 2% of the resettlement population, while the majority were subsistence farmers. The project’s benefits were felt most strongly in Ghana’s Eastern Region and the people who live in its districts.

Low water levels in the Lake Volta reservoir raised concerns about the dam’s ability to provide energy in early 2007. According to some accounts, this is related to drought issues brought on by global warming. Much of this anxiety was alleviated in the second half of 2007 when substantial rains occurred in the Volta River’s catchment area. The dam reached its highest-ever water level in 2010. The flood gates had to be opened at a reservoir elevation of 84.45 m (277 ft), and water spilled from the lake for several weeks, causing some flooding downstream.

Design

The dam is 660 m (2,170 ft) long and 114 m (374 ft) high, comprising a high rock-fill embankment dam. It has a base width of 366 m (1,201 ft) and a structural volume of 7,900,000 m³ (10,300,000 cu yd). The reservoir created by the dam, Lake Volta, has a capacity of 148 km³ (120,000,000 acre⋅ft) and a surface area of 8,502 km² (3,283 sq mi). The lake is 400 km (250 mi) long. The maximum lake level is 84.73 m (278.0 ft) and the minimum is 73.15 m (240.0 ft). On the east side of the dam are two adjacent spillways that can discharge about 34,000 m³/s (1,200,000 cu ft/s) of water. Each spillway contains six 11.5-metre (38 ft)-wide and 13.7-metre (45 ft)-tall steel floodgates.

Akosombo Power Station

Six 170-megawatt (230,000 hp) Francis turbines power the dam’s power plant. Each turbine receives water via a 112–116 meter (367–381 ft) long and 7.2 meter (24 ft) diameter penstock with a maximum hydraulic head of 68.8 m (226 ft).

Power distribution

The dam generates electricity for Ghana and its West African neighbors, such as Togo and Benin. Initially, 20 percent of the Akosombo Dam’s electric output (enough to meet 70% of national demand) was distributed to Ghanaians, while the remaining 80% was generated by the American-owned Volta Aluminum Company (VALCO). The Ghanaian government was forced to pay more than half of the cost of Akosombo’s construction by contract, but it was only allowed to use 20% of the power generated. Some analysts believe that this is a case of neocolonialism. The VALCO plant’s output has decreased in recent years, with the great bulk of Akosombo’s extra capacity being used to meet rising local demand.

Impacts

From the addition of lake transportation, greater fishing, new farming operations along the shoreline, and tourism, the Akosombo Dam helped some industrial and economic enterprises. The electricity generated has served Ghana’s primary needs while also sending power to Togo and Benin, Ghana’s neighbors. Ghana’s industrial and economic growth resulted in increased demand for power, which exceeded the capacity of the Akosombo power plant. By 1981, a smaller dam had been erected downstream from Akosombo in the town of Kpong, and more renovations to Akosombo were required to sustain hydroelectric output. Initially, the dam’s power production capacity far exceeded actual demand; nonetheless, demand has resulted in a doubling of hydropower production since the dam’s commencement. Power demands are growing faster than the current infrastructure can meet. Rolling blackouts and significant power outages have come from power needs and unforeseen environmental developments. Lake levels have been trending lower, occasionally below the minimum required for the Akosombo Dam to operate.

Biological habitat

There has been a continuous loss in agricultural production along the lake and its tributaries since the dam were built at Akosombo. The territory surrounding Lake Volta is not nearly as productive as the land beneath the lake, which was once cultivated, and intense agricultural activity has since depleted the already poor soils. Without the periodic floodings that provided nutrients to the soil before the dam stopped the natural river flow, downstream agricultural systems are losing soil fertility. Fertilizer run-off into the river has increased as commercially intensive agriculture has grown. Eutrophication of the river waters has resulted from this, as well as run-off from surrounding livestock farms and sewage contamination. The nutrient enrichment, combined with the sluggish water circulation, has allowed aquatic weeds to establish themselves (Ceratophyllum). These weeds have grown to be a severe obstacle to water transportation and navigation.

Human welfare

The prevalence of aquatic vegetation surrounding the lake and in its tributaries has caused even more harm to human health in the area. Black-fly, mosquitoes, and snails, which are transmitters of water-borne illnesses like bilharzia, river blindness, and malaria, require weeds to thrive. These diseases have increased dramatically since the dam was built. Since the creation of Lake Volta, disease frequency has increased in resettlement settlements, and the likelihood of infection correlates with the village’s closeness to the lake. This spike in disease frequency has impacted children and fishermen particularly hard. Shrimp and clam populations have also declined as a result of the loss of aquatic habitat. The decrease of oyster populations has harmed the physical health of local inhabitants, as they provided an important supply of dietary protein. Similarly, the rural and industrial sectors have suffered financial losses as a result of the collapse of river aquaculture.

Socioeconomics

The 80,000 people who were forcibly evacuated lost their land, which meant they lost their principal economic pursuits of fishing and agriculture, their houses, their family grave sites, community stability, and eventually important societal values. The resettlement initiative highlighted the sociological challenges of creating “socially coherent and integrated” communities. Due to a lack of planning, communities were relocated to regions that were unable to provide for their prior livelihoods and traditions. Traditional farming traditions were mostly lost due to the loss of naturally fertile soils beneath Lake Volta. Population reductions following relocation have highlighted the terrible living conditions within the resettlement settlements. In the 23 years following relocation, one resettlement community, in particular, saw a population loss of more than 50%. The communities most affected by the Volta River’s development have higher economic risks and experience poverty. Poverty and population pressure have resulted in widespread human movement and the deterioration of natural resources within the Volta-basin area.

Physical environment

The crustal re-adjustments caused by the extra weight of the water within Lake Volta have been recorded as reservoir-induced seismicity. Changes to the river’s delta zone have caused the river’s mouth to migrate eastward, resulting in continued coastal erosion. Changes in river hydrology have shifted the local heat budget, resulting in microclimatic changes including less rain and higher mean monthly temperatures. All of these larger-scale environmental repercussions will exacerbate the issues surrounding local economic disruptions and the resulting severe human welfare conditions. According to a case study by the International Federation of Surveyors, the dam has had a considerable impact on the shoreline erosion of the barrier separating the Keta Lagoon from the sea. According to Dr. Isaac Boateng, river sediment might be reduced from 71 million cubic metres per year to as little as 7 million cubic metres per year.