FRIEND 2002—Regional Hydrology: Bridging lite Gap between Researcli and Practice (Proceedings ofthe Fourth International FRIIIND Conference held at Cape Town. South Africa. March 2002). IAI IS Publ. no. 274. 2002. 329 Water sharing in the Volta basin MARC ANDREINI Center for Development Research, GLOW A Volta Project, PO Box 645, Tamale, Ghana PAUL VLEK & NICK VAN DE GIESEN Center for Development Research, Bonn University, Waller-Flex-Slrasse 3, D-53113 Bonn, Germany e-mail: [email protected] Abstract The geography of the Volta basin is briefly described. This is followed by an overview of water use developments in the two main riparian countries, Ghana and Burkina Faso. Ghana's water use consists mainly of hydropower generation for the urbanized south whereas in upstream Burkina Faso agricultural water use dominates. Analysis of the water balance shows a large sensitivity of surface water resources with respect to changes in precipitation and thereby to global and regional climate change. Finally, the GLOWA Volta project is introduced which addresses the issue of optimal water use under changing water demand and supply. Key words international basins; West Africa; integrated basin management; GLOWA INTRODUCTION No alternative resource can stand in for the critical role that water plays in development. Especially in sub-humid and semiarid regions, water is becoming a critical constraint and is clearly a resource no country can do without. Yet the economic impact of water resources has not enjoyed the painstaking analysis devoted to resources for which alternate options do exist, such as oil. Since the early seventies, there has been an awareness of the economic importance of oil and the relationships among producing and consuming countries have been examined in detail. Now, as the scarcity of water increases, tensions among riparian states sharing international river basins are emerging with increasing frequency, full attention must be focused on the impact of water resources. The countries sharing the Volta River basin are no exception. In this paper, we will show the different expectations with respect to the use of water resources that exist in the main riparian countries, Ghana and Burkina Faso. We then sketch the availability and sensitivity of water supply at the (sub)continental level and the extent to which the riparians depend on water flowing into the country. We finish with a brief overview of a new research project that seeks to model present trends in water supply and demand in an integrated fashion. The Volta River basin drains approximately 400 000 km" (Fig. 1). There are six riparian countries sharing the basin: Ghana, Burkina Faso, Togo, Côte d'Ivoire, Benin and Mali. In this paper we will concentrate on Ghana and Burkina Faso. These two countries comprise the bulk of the basin; approximately three quarters of Ghana (42% of the basin) and two thirds of Burkina Faso (43% of the basin) are drained by the Volta River system. The Black Volta flows from Burkina Faso along the border of 330 Marc Andreini et al. Fig. 1 Overview of the Volta basin. Ghana and Côte d'Ivoire through the Bui Gorge joining the White Volta that also flows south from Burkina Faso. Further east, the Oti River flows from Burkina Faso through Togo then below the western slopes of the Buem ranges before it also joins the other two reaches. Then the river passes through the narrow Akosombo Gorge, site of the dam built to form Volta Lake, before flowing approximately 100 km to the sea. WATER USE IN THE VOLTA BASIN Water use in Ghana Ghana is a country with a long history of mining and today has aspirations to develop a diversified industrial economy. Gold production was an important source of wealth for the African kingdoms located in present-day Ghana and during the colonial period. The original motivation for the proposed construction of a dam on the Volta River was to provide electricity to produce aluminium from locally mined bauxite. Although Ghana was a largely agrarian country at independence, the local leadership was convinced that construction of the Akosombo Dam "was the most important way of bringing Ghana forward to a more balanced economy" (Government of Ghana, 1961). It was claimed that the dam would supply "electric power from the Volta River for industry and for lighting our towns and villages" (Government of Ghana, 1961). Through several admini­ strations, the basic theme of development through industrial expansion has remained. The original generating capacity of the Akosombo Dam was 512 MW at its completion in 1964. After modifications increasing the capacity of Akosombo to 833 MW and completion of the Kpong Dam, downstream, the combined capacity of the two plants is 1060 MW. The Akosombo and Kpong dams are still Ghana's major Water sharing in the Volta basin source of electricity. Demand for power continues to increase especially within the urban-industrial sector (Table 1). Long-standing plans, still in the pipeline, to increase Ghana's generating capacity by developing another dam site in the Bui Gorge, indicate the continued commitment to hydropower as an engine of growth. There are relatively modest irrigation schemes at both Tono and Kpong. Further irrigation development in the north, although spoken of frequently, has thus far been given low priority nationally. In Ghana, water is most often seen as a source of hydropower. Table 1 Yearly electric power consumption by sector in TWh (Andreini et al., 2000). 1980 1985 1990 1995 1998 Aluminium 3.319 0.853 2.789 2.198 0.927 Mines 0.272 0.257 0.315 0.654 0.713 Urban 1.098 1.048 1.615 2.760 3.093 Rural 0.000 0.000 0.066 0.189 0.254 Export 0.440 0.684 0.761 0.285 0.460 Water use in Burkina Faso In contrast, Burkina Faso is a land-locked country with only minimal industrial development. Burkina Faso is an agrarian country; 90% of the population is active in agriculture. At present economic development depends on agriculture because there are no alternatives. The staple crops of sorghum, millet, and corn are grown under rainfed conditions. Failing rains often greatly reduce yields, causing the farmers substantial financial losses. Average yields lie between 800 kg and 1000 kg of grain per ha. Farmers need to invest in more labour, improved seed, and chemical inputs to obtain higher yields. Such investments, however, will remain prohibitively risky, without irrigation to lessen the risk of poorly timed water supply. Burkina Faso lacks economically attractive and environmentally acceptable large- scale dam sites. Irrigation schemes have been developed in Bagré and the Vallée du Sourou and there are modest reservoirs that supply drinking water to Ouagadougou. However, most irrigation development in Burkina Faso takes the form of village-level schemes with imperfect hydraulic control. The total irrigable area in Burkina Faso is estimated to be 160 000 ha (Sally, 1997). The increase in the use of surface water resources over the last 15 years is much larger in Burkina Faso than in Ghana as shown in Table 2. This activity will affect water availability, but the impact is difficult to quantify because of the diffuse nature of the irrigation development. To give perspective to the issue one may remark that the surface area of Lake Volta is 800 000 ha or five Table 2 Reservoir construction in northern Ghana and Burkina Faso (van de Giesen et al., 2001). Burkina Faso: Ghana 1984- 4986: 1999: Increase (%): 1984- 1986: 1999: Increase (%): no. ha no. ha no. ha no. ha no. ha no. ha <5 ha 109 145 377 421 246 191 96 115 113 170 18 48 5-100 ha 72 1704 154 3 444 114 102 18 197 48 534 167 172 >100 ha 5 789 16 23 421 220 2868 2 1184 2 2218 - 87 Total 186 2638 547 27 286 194 934 116 1496 163 2922 95 332 Marc Andreini et al. times the estimated irrigation potential of Burkina Faso. In any case, in Burkina Faso irrigation is seen as the primary non-domestic water use. The tension over water can be characterized as a conflict between rural and urban communities or as a conflict between Burkina Faso and Ghana. In each instance the basic dichotomy may be defined as between those requiring water for the generation of hydropower and those requiring water for irrigation. Already there has been some sparring between the two regarding issues of water use. Irrigated areas in both Ghana and Burkina Faso are modest in size, but the rapid expansion of irrigation in Burkina Faso and the relative stagnation in Ghana indicate different development paths. Even though potential losses from irrigation development in Burkina Faso are small compared to those of the lake, anxiety exists in urban Ghana concerning irrigation and even drinking water development upstream of Lake Volta in general and in Burkina Faso in particular (Gyau-Boakye & Tumbulto, 2000). To help reduce tensions and perhaps to strengthen their claim to the use of the Volta's water, Ghana offered to sell hydropower to Burkina Faso. Ghana wants to charge US$0.09 per unit, but Burkina Faso is ready to pay only US$0.06 per unit (Africa News, 1998). The Government of Burkina Faso maintained that it would be cheaper for them to generate power from thermal plants. LARGE-SCALE WATER BALANCES Having briefly described the diverging views of water consumption in Burkina Faso and Ghana, we now present a water balance as start to thinking about water sharing within the basin. A water balance is the first step in any hydrological analysis and proves especially useful when it comes to a river that drains major parts of the West African subcontinent.