Paleoprecipitation estimates for the Lake Naivasha basin (Kenya) during the last 175 k.y. using a lake-balance model

We modeled the two most extreme highstands of Lake Naivasha during the last 175 k.y. to estimate potential precipitation/ evaporation changes in this basin. In a first step, the bathymetry of the paleolakes at f 135 and 9 k.y. BP was reconstructed from sediment cores and surface outcrops. Second, we modeled the paleohydrologic budget during the highstands using a simplified coupled energy mass-balance model. Our results show that the hydrologic and hence the climate conditions at f 135 and 9 k.y. BP were similar, but significantly different from today. The main difference is a f 15% higher value in precipitation compared to the present. An adaptation and migration of vegetation in the cause of climate changes would result in a f 30% increase in precipitation. The most likely cause for such a wetter climate at f 135 and 9 k.y. BP is a more intense intertropical convergence and increased precipitation in East Africa. D 2002 Elsevier Science B.V. All rights reserved.