Mapping of groundwater potential for irrigation in Ngora District using GIS and remote sensing

Abstract

Climate change has brought about seasonal variations that have adversely affected agricultural systems. Dependence on rainfall for crop production is no longer a feasible and reliable option due to the high rainfall variations which make crops vulnerable to the changes. Proximity to surface water bodies is also a challenge. Consequently, groundwater Demand has increased significantly owing to increasing population and Demand for plant-based foods in Ngora District. This study aimed to determine the potential areas for groundwater use for agriculture sector development in Ngora District. ArcGIS 10.7.1 was utilized for geospatial analysis, which is referred to as Multi Influencing Factor (MIF) methodology. Seven parameters including land cover, geology, soil, rainfall, underground faults (lineament) density, drainage density, and slope, were used for the analysis. Considering relative significance and influence of each parameter in the groundwater recharge rating and weightage was given and potential groundwater areas were classified into very high, high, moderate, low and very low. The result of classification disclosed that 66.52% corresponding to 478.95 km2 of the area has moderate groundwater potential, 23.94%, (172.34 km2) of the area has high potential, 9.45%, (68.01 km2) has low potential, 0.08%, (0.55 km2) has very high potential and 0.02% (0.16 km2) of the area has very low potential for groundwater agricultural uses. Field surveys for water table indicated groundwater potentiality, which was high for Kobwin subcounty which was characterized with boreholes exhibiting high yields of 4.3953 - 5.409 m3/ hour and providing water all year round. However, groundwater potentiality was poor in Kapir, characterized with lower yields of 0.3398 to 1.3536 m3/ hour and some of the boreholes occasionally going dry in the dry season. Moreover, the study effectively revealed that remote sensing and GIS can be used as potent tools for mapping potential sites for groundwater utilization. Furthermore, MIF technique can be a suitable approach for determination of groundwater potential zones, which can be applied for further research in different areas.