Eastern Africa is home to some of the greatest water sources in the world. The three most notable water bodies and systems and of relevance to the East Africa region include:
- Lake Tanganyika - the greatest single reservoir of fresh water on the continent and second deepest in the world (UNEP, 2006),
- Lake Victoria - Africa’s largest lake and the world’s second-largest freshwater lake, and
- the Nile River Basin - source of the Nile, the longest river in the world.
The distribution of water varies significantly within the region. The region has four major aridity zones: moist sub-humid mainly in Uganda, Rwanda and parts of Burundi, dry sub-humid (parts of Uganda, western Tanzania), semi-arid (parts of Tanzania) and arid, most of Kenya. The western component of East Africa, including Burundi, Rwanda and Uganda along with the central part of the continent are considered to have a rain surplus, while large parts of Kenya are considered to have a very large water deficit (UNEP, 2010).
Both of the great lakes, Lakes Victoria and 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 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 mainly as a result of human activity in both the catchments and river basins.
- Sedimentation and siltation are exacerbated by increasing 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;
- Lack of systematic knowledge, data and monitoring of groundwater aquifers.