MODELING OF GROUNDWATER LEVEL IN RIVER MALLAM SULE CATCHMENT AREA, NIGERIA

Abstract

The demand for water has increased over the last few decades, due to increase in population, social and economic development in different part of the World. The drying up of boreholes and wells worsens the problem of water scarcity in Yobe State because of the high demand for water. The study aimed at stimulating and predicting the groundwater level in River Mallam Sule catchment Area, Nigeria. Resistivity data, Gravity Recovery and Climate Experiment (GRACE) data, Digital elevation model, stream flow data, and Land Use Land Cover map. Soil Water Assessment Tool (SWAT) was used as a model to simulate and predict the groundwater level. It was calibrated successfully. Descriptive and Mann Kendall trend was used to compute trend in the variability of groundwater. The result of the study shows the level of surface water anomalies was lowest in 2008 and highest in 2015. Similarly, the level of soil moisture was lowest in 2018 and highest in 2004, terrestrial water storage was lowest in 2008 and highest in 2014 while groundwater level was lowest in 2006 and highest in 2008. The calibrated model was used to predict the future scenario of groundwater in the study area for 2030s, 2060s and 2100s, using 1981 to 2020 as the base line, the calibration was successful. The result of inter decadal trend analysis of projected groundwater from 2020 -2050 shows a negative trend from 2020-2049 and a positive trend in 2050. The study concluded that the temporal variation of groundwater, surface and terrestrial water storage anomalies has moderate variability with positive trend, while soil moisture and groundwater anomalies shows a negative trend, this implies that there is a decrease in the soil moisture and groundwater. The study recommended that there should be alternative source of water to reduced sustained pumping of groundwater which lead to the decline in groundwater.