INVESTIGATION OF GROUNDWATER POTENTIAL USING GEOPHYSICAL ELECTRICAL RESISTIVITY METHOD IN DHOBLEY DISTRICT, JUBALAND STATE, SOMALIA

This study aims to investigate the groundwater potential in Dhobley district, Jubaland state, Somalia, using the geophysical electrical resistivity method. Groundwater is a vital resource in arid and semi-arid regions, such as Somalia, where access to clean water is limited. The electrical resistivity method is a widely used geophysical technique for assessing subsurface hydrogeological conditions and has the potential to identify areas with high groundwater yield. The study area is located within the sedimentary rocks with alluvial as common types of rocks. The data acquired from seven (7) VES stations using ABEM Terrameter (SAS 1000) was tabulated in a Table 4.9 which shows the resistivity, the thicknesses and the number of layers for each VES station. The data was analyzed using computer software called IPI2WIN, which yield an automatic interpretation of the apparent resistivity.  The VES result revealed that the study comprises the top soil, clay, sandy clay and weathered limestone. The first layer or top soil consists of sandy soil with resistivity range from 23Ωm to 266Ωm and thickness of range from 0.63m to 2.82m (VES 1 to VES 7). The second layer composed of clay its value ranges from 3.57Ωm to 37.7Ωm with thickness varies from 0.898m to 58.5 m (VES 1 to VES 7), and the third layer composed of sandy clay with resistivity ranges from 5.54Ωm to 121Ωm with thickness varies from 2.26m to 19.1m (VES 1, VES 2, VES 5 and VES 7). And the fourth layer composed of clay its value ranges from 3.78Ωm to 54.3Ωm with thickness varies from 22.8m to 48.7m (VES 2 and VES 5). The fifth layer of VES 2 indicates the presence of weathered limestone with a resistivity value of 355Ωm and a thickness of 31.7m. However, by considering the result obtained it is an indication that the study area has a good land for boreholes and other engineering and architectural activities, due to the features that enhance groundwater permeability and storage. For safety measures, in the deep aquifers which are ranges from 250m to 270m, the random dumping of waste products such as solid and liquid materials must to be avoided in nearby boreholes area in order to prevent waste contaminate to aquifer replenishment