Merti Aquifer Recharge zones determination using geospatial technologies.

Abstract

The Merti Aquifer is a fresh water aquifer in an arid area in the North Eastern part of the country straddling between Garissa and Wajir districts. In this study, the aquifer is defined by the 1,000 mg/l line of the Total Dissolved Solids (TDS). This starts West of Habaswein to Liboi on the East, along the Ewaso Ng’iro River drainage way (known as the Lagh Dera). It generally follows the Ewaso Ng’iro River with water flows encountered only during flooding events. Development of the aquifer since the 1940’s to date by governmental agencies and its development partners through drilling has resulted in generation of, over time, data and information on its water resources. This is arid region and it is essential to identify the potential recharge zones so that these can be protected from groundwater contaminants. In this research, borehole data and water sample chemical analysis results were obtained from the Ministry of Water and Irrigation and reports by various researchers. A spatial database for the aquifer was developed. Remote sensing data was used to characterize the land covers in the area and to delineate lineaments in the study area. The geophysical and geochemical characteristics with the derivative products from remote sensing were combined within a Geographic Information System. By applying spatial analysis techniques, potential recharge zones were found to be located between Habaswein and Liboi, providing a solid basis that confirms conclusions made by earlier researchers.