Evaluation of Groundwater Yield Capacity Using Dar-zarrouk Parameter of Central Kwara State, Southwestern Nigeria

The quest to meet the required groundwater need of citizens of Nigeria, especially Central Kwara State for both domestic and industrial application in the face of scarce water resources, occasioned by incessant borehole failure/low yield, has prompted researches for viable source of water. The central Kwara state falls within the basement complex region of Nigeria known as the hard rock terrain, where availability of groundwater is dependent mainly on structural features and their dispositions to yield groundwater. The second order parameters were determined from the interpretation of vertical electrical sounding results. These Dar-zarrouk parameters was used to determined the groundwater yield index value by multiplying the coefficient of anisotropy (λ) and total transverse resistance (T) and was used to model the groundwater yield capacity map. The north-eastern and the central region of the area has the highest prospect for groundwater yield while part of the north western, north central and the south eastern part has medium prospect for groundwater yield and the rest of the area has prospect for low yield except for the south western end. Part of the south western and the middle part of the north eastern part has lean or least prospect for groundwater yield. The boreholes data and hand pump well across the entire study area were used to validate the accuracy of the groundwater yield capacity map.