Sub catchment water balance analysis in the Thika-Chania Catchment, Tana Basin, Kenya

Abstract

Water scarcity is a growing issue in the Thika-Chania catchment, Kenya. Water allocation planning is used to manage water resources fairly, equitably and to avoid over abstraction. Water allocation planning depends on quantitative information on water availability. Unfortunately there is a lack of data available on water yield due to an inadequate monitoring system. This thesis aims to provide quantitative information on water availability through use of the Soil and Water Assessment Tool (SWAT), using water balance analysis to determine availability and demand. The SWAT model provided acceptable representation of stream flow, calibrated to a Nash Sutcliffe 0.58. The Environmental flow was found to vary across the catchment, ranging between 0 and 1.75 m3/s. The north edge of the downstream area was found to have the greatest issue with water scarcity due to higher levels of water demand, higher evaporative loses and less rainfall.