Water resources assessment of the Volta River Basin.
The Volta Basin is a transboundary basin shared by six riparian countries. In 2007, the Volta Basin Authority (VBA) was established and it was mandated to provide legal and institutional arrangements among the riparian countries for managing the water resources of the Volta Basin. The transboundary diagnostic analysis commissioned by the VBA has highlighted five key challenges that the basin faces: changes in water quantity and seasonal flows; degradation of ecosystems; water quality concerns; governance; and climate change. A key mandate of the VBA is authorizing the development of infrastructure and projects that could have a substantial impact on the water resources in the basin. The water resources in the Volta Basin contribute significantly to the economic development of the six riparian countries. This is the case particularly for Burkina Faso and Ghana where more than 60% of the area of each country is located within the Volta Basin. The water resources are being utilized for agricultural production, domestic water use, livestock watering and hydropower production. Increasing demands on the resources have created competition between sectors and countries. Widespread construction of hydraulic infrastructure of different sizes and for different purposes has been developed over the years. Climate change and variability, and upstream water resources development have impacted the hydropower generation of Akosombo and Kpong dams, located close to the Volta Estuary. This comprises about 70% of the installed hydropower capacity of the basin. The Volta Basin is also endowed with freshwater ecosystems which provide various ecosystem services that contribute to local livelihoods, and larger-scale basin objectives, by providing food, fuel and construction materials, regulating flows (reducing peak and increasing baseflows) as well as by providing habitats for animals, such as migrant birds, which may attract recreational activities. Both natural and built infrastructure provide benefits. Some benefits such as hydropower are only provided by built infrastructure but others, such as water treatment and flood control, can be provided by both natural and built infrastructure. In addition, natural infrastructure supports the performance of built infrastructure, through providing water of a certain quantify and quality. Degradation of natural infrastructure is a key concern in the Volta Basin and may affect the performance of downstream dams. On the other hand, natural infrastructure may be affected by the development and management of built infrastructure, as is observed downstream of the Akosombo Dam. Future water resources development in the Volta Basin requires an integrated approach towards built infrastructure development and investments in natural infrastructure to ensure optimal basin-wide benefits.