An Investigation of Groundwater Potential in the Timau River Basin, Kenya

Abstract

Water scarcity is Kenya is becoming a greater concern as a result of climate change and population increase. In the Timau River Basin, a small catchment within the Upper Ewaso Ng’iro North River Basin, northwest of Mt. Kenya, substantial agricultural water use is attributed to both small-scale and commercial farms. With a relatively recent influx of immigrants to the lush mountain slopes, a highly productive region for agriculture, increased upstream water abstraction from the Timau River and others has left riverbeds to run dry in the more arid downstream areas. Commercial flower farms also use groundwater, but the resource is not significantly exploited among small-scale water users. Data from boreholes in and around the Timau River Basin were investigated and analyzed in order to assess the hydrological characteristics of the catchment. Static water levels were used to establish a potentiometric water surface, which generally follows the contours of the land surface. Pumping logs were utilized to calculate the hydraulic properties of the aquifers. These properties, along with other characteristics of the aquifer and the regional climate, were used to create a simple groundwater flow model using MODFLOW-2005 and Groundwater Vistas. Results from the model indicate that the region has significant potential for increased groundwater use, with maximum pumping potential nearing six times current rates. However, the model depicts some negative effects on streamflow due to greater groundwater abstraction. Thus, this study demonstrates that development of groundwater should by highly considered by water governance institutions in Kenya, though should undoubtedly involve further research.