RAINFALL INCIDENCES AND GROUNDWATER CHARACTERISTICS IN THE SEDIMENTARY

Groundwater fluctuation is an important phenomenon in water supply within semi-arid regions. Sokoto state has a dry season of 8 months and rainy season of 4 months; this has a profound impact on groundwater level. This study examines groundwater fluctuation within Sokoto metropolis. Groundwater levels in selected shallow wells were monitored after 3 incidences of rainfall in 20 shallow water wells between May and June, 2011. Measuring tape and Global Positioning System (GPS) were used as instruments of data collection. The water levels and the GPS values served as input into Surfer 10 Digital Elevation Mapper, using 3D (Dimension) digitizing and one grid vector mapping techniques. Also, digitized map of Sokoto metropolis was imported into Surfer 10 digital elevation Mapper environment to enable the positioning of the sampled sites of water levels for both dry and rainy events. One grid vector was used to classify Sokoto metropolis into areas of high, moderate and low water levels. One way ANOVA statistical technique was used to test differences in rainfall and water level fluctuations in shallow wells of Sokoto metropolis. The results showed that there were no significant variations between levels of groundwater with rainfall events. It also showed that groundwater flow in Sokoto metropolis is in 4 different directions. In addition, Sokoto metropolis was classified into 6 regional groundwater regions. The paper suggests a need for further study