Introduction

The Volta Basin is located in West Africa. The main channel measures 1400 km and drains 400,000 km2 of semi-arid and sub-humid savanna (Fig. 9.1). The basin lies mainly in Ghana (42%) and Burkina Faso (43%), with minor parts in Togo, Côte d'Ivoire, Mali and Benin. Ghana occupies the downstream part of the basin. A dominating feature of the basin is Lake Volta, which is the largest man-made lake in the world in terms of surface area (4% of the total area of Ghana). The lake was created to generate hydropower at Akosombo and Kpong (1060 MW) (Dickson and Benneh, 1987).

It is estimated that the country had a total population of about 18.9 million people in 1998, with an annual growth rate of about 3% per annum. About 65% of the total population in 1995 was rural, which had been 57% in a 1992 survey. A survey conducted by the Community Water and Sanitation Division (CWSD) of the Ghana Water and Sewerage Corporation (GWSC) in 1992 found that 57% of the population had access to a safe drinking-water supply. In rural areas 46% of the population, and in urban areas 76% of population, had such access.

The main land use in the Volta Basin is short bush fallow cultivation along the banks of the river network, and less intensive bush fallow cultivation elsewhere. Animal grazing is common, while the lake shore is extensively settled by fishing families. Charcoal production, involving the cutting of wood, becomes an extensive economic activity in the southern dry forest and transitional environments, e.g. the various parts of the Afram sub-basin on the west shores of Lake Volta. Since the 1960s, the Afram plains and other areas in the south, have been the focus of increasing settlement and agricultural development, having been generally thinly populated in the past (Dickson and Benneh, 1987). The forested and transitional areas are intensively farmed with

© CAB International 2004. Climate Change in Contrasting River Basins

Fig. 9.1. The Volta River Basin; shared by Ghana, Burkina Faso, Ivory Coast, Togo, Benin and Mali.

Fig. 9.1. The Volta River Basin; shared by Ghana, Burkina Faso, Ivory Coast, Togo, Benin and Mali.

cocoa, coffee, plantain, cocoyam, cassava, oil palm and maize on small bush fallow plots. Some timber extraction takes place in these areas. Recent developments, particularly below the Akosombo Dam, include irrigated rice, sugar and vegetable cultivation in the areas immediately adjoining the Volta River.

Water resources play a vital role in the promotion of economic growth and the reduction of poverty in Ghana. There is rapidly increasing demand for water in industry, particularly hydropower generation, agriculture, mining, recreation, domestic and industrial consumption, and environmental enhancement. With these demands, water supplies will be severely stretched and pollution problems and environmental degradation are likely to increase. The situation will worsen as the population continues to grow, urbanization increases, the standard of living rises, mining becomes increasingly widespread and human activities are more diversified. Lower rainfall amounts over the years due to longer dry seasons have led to more and more tributaries, as well as main rivers, drying up quickly, leading to lesser amounts of surface and ground water available for the increasing population.

Ghana is drained by three main river systems: the Volta, South-Western and Coastal River Systems. They cover 70%, 22% and 8%, respectively, of the total area of Ghana. The total annual runoff from all rivers is 56.4 billion m3 of which 41.6 billion m3 is accounted for by the Volta River (Table 9.1). The mean annual runoff from Ghana alone is 38.7 billion m3, which is 68.6% of the total annual runoff. The Volta, South-Western and Coastal systems contribute 64.7%, 29.2% and 6.1%,

Table 9.1. Water resources availability in Volta Basin.

Area (km2) Mean annual runoff (x 106 m3)

River Within Outside within Within Outside within basin Ghana Ghana Total Ghana Ghana Ghana Total Ghana

Volta basin system

Black 35,107 113,908 White 45,804 58,948 Oti 16,213 56,565 Lower 59,414 3,237

Total 165,712 232,658

149,015

23.6

4,401

104,752

43.7

6,073

72,778

22.3

2,498

62,651

94.8

9,114

398,370

41.6

24,175

3,272

7,673

57.4

3,492

9,565

63.5

8,717

11,215

22.3

9,842

92.6

16,209

40,384

59.9

respectively, of the annual runoff from Ghana. Runoff is marked by wide variability between wet season and dry season flows. Table 9.1 gives a summary of surface water availability within and beyond the country.

At the end of 1988, 12% of the total land area of Ghana was taken by cropland, 15% by permanent meadows and pastures, 36% by forest and woodland, while other land accounted for 37%. As of 1998, the total area cultivated under the four major starchy crops of the country (cassava, yam, cocoyam and plantain) increased from 1.21 to 1.31 million ha, while the total area cultivated for the major cereal crops increased from 1.28 to 1.34 million ha. The land under irrigation formed a negligible part of the arable and permanent cropland. Presently, only 10,000 ha out of a potential 346,000 ha are under irrigation.

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