Lake Baringo

Abstract

Lake Baringo is the largest freshwater lake in Kenya and lies in a closed basin with probable outflow through fractured lavas. It lies within the northern part of a rhomb-shaped graben and is mainly fed by rivers, dominated by the Molo and Perkerra, with minor hot spring contributions. The semi-arid climate has a peak rainy season around July to November with potential annual evaporation exceeding annual precipitation. A temporary thermocline develops at 0.2–0.5 m with holomictic conditions prevailing in the late afternoon due to wind mixing. The Na+–Ca2+–HCO3− waters contain minor Cl− and SO42− and are very turbid with Total Dissolved Solids of 0.6–0.8 g L−1. Microcystis aeruginosa dominates the phytoplankton with diatoms being scarce. Zooplankton include rotifers, copepods and ciliates. Ostracods are common in shallow water. The fish fauna has been substantially altered by human interventions and fishing activities. Feldspathic mud and laminated clay dominate the lake floor with stromatolites forming locally along shorelines depending on lake levels and turbidity. Pollen, diatoms and geochemical data from short cores record lake level changes and a major desiccation event during the last few hundred years. Outcrops record high-lake-level shorelines during the African Humid Period. Late Pleistocene-Early Holocene sediments at Kokwob Murren preserve a stratigraphic record of environmental change.