Investigation of the Impact of Drought on Groundwater: A Case Study of Yobe State, Nigeria

Abstract

Drought which occurs as a result of climate variability has devastating implications for human health especially in northeastern Nigeria, where it is known to cause malnutrition due to food and water shortage, epidemic (cholera and typhoid fever) and meningitis due to high temperatures. In view of the consequences of drought in the study area, this study investigated the impact of drought on groundwater in Yobe State, northeastern Nigeria using geophysical and meteorological data. The Vertical Electrical Sounding (VES) delineated five geologic layers, which are the topsoil, clay, sand, sandy clay and sand. Two aquifers were delineated in the study area, the first aquifer is unconfined and it is very close to the Earth surface in some areas within the study area, while the second aquifer is confined at a great depth. The temperature and the Actual Evapotranspiration analysis for the study area showed increasing trend which indicates significant loss of water from the ground. The first aquifer is mostly affected by drought due to its proximity to the Earth surface. The lowering of the water table and significant soil water loss in the study area manifested as low borehole yields during drought. Groundwater recharge for the period of the study (40 years) showed a decline trend. The droughts frequency and severity were evaluated using Standardized Precipitation Index (SPI) and Palmer Drought Severity Index (PDSI). The results obtained showed that the study area had been involved in series of drought regimes, whose degree of impact ranged from moderate to extreme situations. Based on the findings of this study, it is recommended that more trees should be planted in the study area to reduce evaporation and evapotranspiration. More research and development activities should be encouraged to improve effective adaptability to drought and climate change in the study area.