Thursday, October 11, 2012

Hydrology and Soils of the Serengeti National Park

The Serengeti National Park is supported by the Mara River Basin, which is located in both Tanzania and Kenya, ultimately draining into Lake Victoria that borders the park on the western side. Lake Victoria in itself has ten river basins that flow into it; the Mara River Basin is only one. The drainage patterns for the basin are primarily dendritic, however angular patterns have been noted. For most of the year, the rivers of the Mara River Basin are dry, yet for the wet season, the month of December as well as March through May, they flood. The water table of the river basin remains higher along the rivers even during the dry season.

The Mara River Basin, which crosses the borders of both Tanzania and Kenya.

A section of the Mara River Basin during the drought season.

Lake Victoria at sunrise

There are four different types of soils found in the Serengeti National Park which are black cotton, alluvial, granitic, and lateric soils. The black cotton soil is found mostly on the western corridor and is comprised of black clay. The soil of the park is highly influenced by the ash deposits of the volcanoes on the Ngorongoro Highlands making it a very particular type of soil containing many types of salts, such as potassium, sodium, and calcium. During the wet seasons, the salts from the soil are swept down into the soil where they dissociate and accumulate less than a meter below the surface. There, the precipitates form a hard layer known as a “petrocalcic horizon”, which is the lateric soil, making the soil impenetrable to tree roots, thus hindering the growth of trees on the plains, and reversely, the thriving of grass.
The underlying granitic rocks are highly resistant to weathering also due to the effect of the ash deposits from these volcanoes, making the weathering process slower than usual in this area. 

Savannah soil profile
Black cotton soil of Tanzania

 Sources for information: 

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