Both of the great lakes, Lake Victoria and Lake Tanganyika, and ultimately, the White Nile depend on the regional catchments referred to as Water Towers of the region. The Water Towers of eastern Africa are a collection of mountain ecosystems and associated river basins. These areas have a major influence on regional hydrology and global climatic cycles.
The majority of the main water towers in the region are under very serious threat and several are severely degraded; the threats are anthropogenic in nature. Many of the forests have been cleared extensively mainly for agricultural purposes and human settlements and face additional pressure from surrounding human settlements.
Important regional issues
It is clear that the region has significant volumes of water and that these volumes could be enhanced by the preservation and restoration of the region’s water towers. However, to achieve water security, there is a need to address important policy issues regionally including:
- Though water resources are available, they are not evenly distributed nationally and regionally.
- Access to water is critical; water storage and transportation is currently not sufficiently developed to deal with the scale of regional water availability, shortcomings are further emphasised during natural disasters such as drought.
- Water quality is declining significantly primarily as a result of human activity in both the catchments and river basins.
- Sedimentation and siltation are exacerbated by increased deforestation; pollution occurs as a result of untreated industrial, domestic wastewater and solid waste as well as boat discharges; high levels of eutrophication and anoxia occur as a result of agricultural run-off and domestic wastewater and solid waste discharge.
- Lake Victoria is relatively shallow with high rates of evaporation and almost completely reliant on rainfall (Kizza et al., 2009; Awange et al. 2008), thus pollution can be concentrated within the lake.
- Lake Tanganyika is already anoxic beyond a depth of 35m (UNEP 2004) and most importantly as a closed basin, water and pollution are long lived; it takes approximately 7,000 years for water to be flushed from the lake.
The main challenges to achieving water security are therefore:
- The destruction of the ecosystems underpinning the region’s water towers;
- The lack of physical infrastructure to store and transport water from areas of high availability to those of low availability;
- High population density that continues to increase above the continent’s average (UNEP, 2010);
- Poor waste management;
- High rates of evaporation particularly of Lake Victoria; and
- Lack of systematic knowledge, data and monitoring of groundwater aquifers.