Lake Turkana description

Lake  description

Lake Turkana, is one of the lakes in the Great Rift Valley of East Africa (Fig. 1). The lake is about 250 km long and 15–30 km wide, with an average surface area of nearly 6750 km². The lake catchment is 145 500 km² and extends over Ethiopia in the north, Kenya in the south, and Sudan and Uganda in the west. The lake has a maximum depth of nearly 110m and an average depth of 30 m. Three rivers, the Omo, Turkwel, and Kerio, constitute the lake inflows. The Omo River is perennial and meanders nearly 1000 km before emptying into the northern tip of the lake. It accounts for more than 80% of the lake inflows (Ricketts and Johnson, 1996). In contrast, the Turkwel and Kerio Rivers are intermittent and contribute little to the total volume of the lake (Carr, 1998). The climate of Lake Turkana is hot, arid, and moderately stable all year. Lake Turkana basin has four distinct seasons with two dry periods (December–February and July–August) and two rainy seasons (March–June and September–November). The average rainfall over the lake is less than 200mmyr⁻¹ (Halfman and Johnson, 1988). Lake Turkana is considered an endorheic lake with no surface outlet and insignificant seepage (Ricketts and Johnson, 1996). The outflow is dominated only by evaporation (Velpuri et al. 2012).

As Lake Turkana is dependant on the Omo River for almost 90% of its inflow, this river is the lake’s “umbilical cord”. If the Omo River inflow is reduced, the lake level and associated biomass will fall. If the Omo river flow patterns are modified, the lake ecology will be impacted. The lake is almost entirely within Kenya, whereas the Omo River is entirely within Ethiopia. Hence management of the Omo Basin and lake water resources presents trans-boundary challenges.

The status of Lake Turkana’s fisheries resource today needs to be reviewed, as changes will have taken place since the detailed studies were done over 30 years ago. The fisheries resources is in “a perpetual state of change”, undergoing “unpredictable and drastic transformations” (Kolding, 1993), and will have been impacted by catchment degradation since the authoritative studies of that time, by changes in runoff and sediment runoff patterns, and by population pressure and associated increased and poorly regulated fishing, and increased livestock grazing of littoral zones.