Geological controls on groundwater geochemistry in Butula area, Busia District, Kenya

Abstract

The geology of Butula area comprises mainly of rocks of the Archaean Greenstone belt of Western Kenya, especially the metavolcanics of the Nyanzian Group and the metasediments of Kavirondo Group both of which are intruded by the Mumias granite. High groundwater potential area is found within the Kavirondian sediments and the Mumias granite. Water rest levels in the wells within this area ranges in depth from 3.5-18.98m. The groundwater is slightly acidic, sodiumbicarbonate type. Iron and manganese were found to be in excess of the WHO recommended limits for potable water quality while fluoride was in relatively low amounts. PCA and factor analysis revealed that Ca, Cl, Conductivity, F and Fe are the major principal components that determine the groundwater chemistry in this area. It is established that the area is underlain by a single (1) groundwater field, and a significant component of the groundwater recharge is derived from outside the sutdy area. The waters are, in general, suitable for most purposes be it domestic, agricultural or industrial.