into Lake Victoria, and is therefore functionally and ecologically related to the socio-economic activities in Lake Victoria and along the River Nile. Altitudes and Ranges The altitudes in the basin range from 2,932 m around the sources in the Mau Escarpment to 1,134 m around Lake Victoria. The amount of precipitation varies according to these altitudes. The Mau Escarpment receives most rainfall with a mean annual rainfall between 1,000 and 1,750 mm. The transboundary middle savannah grasslands receive an average between 900 and 1,000 mm, and the Kenyan lower Loita hills and the area around Lake Victoria only about 700 and 850 mm rain per year. On top of this rainfall variability in space, the region is also known for its rainfall variability in time, which means that the different areas all receive variable amounts of rainfall over the year. The rainfall seasons are bi-modal, with the long rains starting in mid-March to June with a peak in April, while the short rains occur between September and December. The Mara's Effects The river is a vital source to grazing animals within the reserve. Although during the dry season it may often appear shallow, it may swell to up to twice its normal size after heavy rainfall. This can create rapids in the river, which may lead to shortage of food for predators that cannot cross the river to hunt. See also Nile River Nzoia River Yala River Nyando River Maasai Mara Serengeti National Park Mara Region Narok County References External links gabepalacio.com: Mara River virtual Tour (requires QuickTime plugin) The Mara Triangle The Mara River defines the boundaries of the Mara Triangle in the Masai Mara Serengeti Mara River flows from Masai Mara into Serengeti Rivers of Kenya Rivers of Tanzania International rivers of Africa Tributaries of Lake Victoria Geography of Mara Region