Modelling of potential sites for underground water in semi arid areas

Abstract

Kajiado County in southern Kenya experiences insufficient amount of rainfall and people living in this region face alot of water challenges.The main economic activities in the area include pastoralism, livestock herding, tourism and agriculture which require sustainable water sources. The current water sources in the area are mainly seasonal rivers that provide unreliable water supply. The few existing boreholes are long distances apart. Amount of rainfall experienced in this region is insufficient and unreliable. This study sought to identify alternative, reliable, and sustainable water sources to complement the current unreliable water sources. Underground water is sustainable and its identification and utilization could help in solving the current water issues. To address the problem of water shortage, Remote Sensing and GIS techniques were applied in analyzing and identifying suitable sites for underground water. Necessary variables for identifying underground water were identified with assistance from expert opinion. Current water resources were characterized, a geodatabase created and a model for underground water developed. Land cover, slope, lithology, soil, lineament and climate comprised the six variables used. GIS technology was integrated with Analytical Hierarchy Process (AHP), for Multi Criteria Evaluation (MCE) in determining the factors necessary in locating suitable areas. Identified criteria were combined using weighted overlay approach. Results indicated that 51% of the study area was viable for sourcing underground water. Exploitation of this resource would mean sustainable source of water. The suitable locations were well distributed in the County except in the central area which generally falls under unsuitable areas for sourcing underground water. Remote Sensing and GIS were noted as suitable tools for identifying suitable locations for sourcing underground water. Decision makers could adopt this approach in making informed decisions on where to sink new boreholes.