Estimating the groundwater storage for future irrigation schemes

Abstract

Presented in this paper is a feasibility study of groundwater for agricultural use (irrigation) in Northern Ghana. The study was conducted using geo-electrical data, boreholes drill logs, results of water quality, and results of the pumping test. The geo-electrical results were to unearth the lithology of the study area; it was found to be underlain with varying geology of both Precambrian and Paleozoic sedimentary formation. These formations consist of phyllite, schist, granite, meta-sediments, and meta-volcanics making up the Precambrian and sandstone, shale, siltstone, mudstones, granitiods also, of the Paleozoic sedimentary. Areas of low resistivity were targeted for drilling per the geophysical results of the profile, values between 24 and 100 ohm.m were zones of probable groundwater occurrence in the study. The groundwater storage capacity and the extractable storage capacity were estimated to be approximately 710,000 km3 and 290,000 km3. The pumping test results acquired from 81 boreholes from the study were used to analyze the sustainability. However, groundwater depth was studied using the Static water level (SWL), areas of SWL around 22 m and 25 m are likely to have a shallow depth whereas areas of 17 m would have deeper groundwater depth. HIGHLIGHTS Groundwater resistivity was determined from the VES values.; The groundwater storage and extractable storage were computed from borehole data.; Overburden thickness suggest thick weathering.; Pumping test reveals the quantity of groundwater discharged.; Groundwater irrigation might be possible per this study.;

Keywords

• geo-electrical
• groundwater
• paleozoic
• precambrian
• pumping
• sedimentary