Estimation of Groundwater Potential Using Evidences From Pumping Test Data a Case Study of Ilorin Metropolis Southwestern Nigeria

Considerable increase in water demand to in many parts of sub-Sahara Africa poses a challenge for water managers to develop creative and cost-effective approaches in water resources exploration and management. Ilorin city, south western Nigeria is reflective of these needs the population growth rate have given rise to a considerable spike in water needs. Groundwater a hidden gem in the earth subsurface poses a veritable solution to meeting water needs and overall development of a country’s economy. However, understanding the dynamics of this resource pose a challenge hence the relative inefficient exploitation of its potentials in the sub region. Pump test of existing boreholes serves as a vehicle to understand and evaluate primal characteristics of groundwater system in view of exploitation. In the study location pump testing was conducted in seventeen locations within the metropolis.  Aquifer parameters such as transmissivity, hydraulic conductivity, specific capacity, discharge was determined. The values of transmissivity estimated by aquifer tests ranged between 7.19 m²/d (northwestern region) and 0.259 m²/d (southeastern part). This is further classified into high (>1.62), medium (0.59-1.62) and low (0.259-0.59) transmissivity. The specific capacity values within the study area also ranged between 8.37 and 0.90 l/min/m. Locations with specific capacity > 3.6 were considered as high, those ranging between 1.42 and 3.6  l/min/m were classified as medium while those between 0.9 and 1.41 l/min/m were classified as low. Discharge (Q) within the study area was estimated with the values ranged between 114.91 and 44.93 m³/day. Location with values greater than 79 m³/day were classified as high, those with the range of 51.0 and 75.6 m³/day as medium while those between 32.82 and 50.1 m³/day were considered as low discharge rate. Hydraulic conductivity values ranged between 1.375 and 0.025 m/day. It is classified as follows; high >0.313 m/day, medium: 0.087-0.313 m/day while low: 0.25-0.08 m/day. Groundwater potential for majority of the location fall within medium range of the aquifer parameters estimated. This implies that the groundwater in Ilorin municipality is medium or moderate in nature.