One of the case studies of this year's Stockholm Water Symposium is Lake Victoria, an important natural resource in east Africa, which is under stress. The rapidly growing populations in the three riparian states of Kenya, Uganda and Tanzania creates a heavy pressure on natural resources and environment conditions. Lake Victoria is also the source of the Nile river, which means that this river transports pollution from the lake all the way to the Mediterranean.
With a surface area of 68,000 sq km, lake Victoria is the world's second largest freshwater lake and is rather shallow with a mean depth of only 40 m and a maximum depth of around 80 m. Several small bays and wetlands dot the shoreline of the lake. The lake is situated in the equator and its water regime is characterised by high precipitation and evaporation in comparison with river inflow and outflow. Precipitation and evaporation, which are estimated to be of equal size, account for 85 per cent of the input and output respectively.
Pollution in Lake Victoria is increasing due to the rapid population growth around the lake basin. Surrounding urban centres have been found to possess a defunct sewage system that releases raw sewage into the lake. Industries in the region are not well-equipped with efficient wastewater treatment plants and they often dump their effluent directly into the lake. In Tanzania, the gold rush puts an additional stress on the environment, with discharges of heavy metals such as mercury. Land use in the catchment zone too plays a major role in the pollution process, since oil erosion leads to higher loads of sediment in the rivers.
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