Groundwater Storage Analysis Using Deterministic Model Approach for Water Resources Management of Zamfara part of Sokoto-Rima Basin, Nigeria

Abstract

The study area is entirely located within the Sokoto-Rima hydrological basin of Northwest, Nigeria. Groundwater is widely used for drinking, domestic and agricultural purposes in Zamfara water catchment. The mismanagement of groundwater resources could cause negative effects including depletion of aquifer storage and groundwater level decline. To assure sustainability of the available resources, determination of groundwater budget is necessary. Deterministic model approach was used, which required three quantities (Available water quantity, Abstractible and Storable water volume). In this study meteorological water budget (MWB), water level fluctuation (WTF), and groundwater budget based on geological framework (GBBDF) were used to estimate water budget. Groundwater recharge and abstraction rate were calculated from 280 borehole data across the water catchment area. The average groundwater budget of the study area was calculated as 111,693,470 m3/year with the MWB method and it was calculated as 111,342,057.3m3/year and 73,463,099 m3/year with the WTF and (GBBDF) methods respectively. The groundwater abstraction for domestic/agricultural uses was calculated to be higher to that of aquifer recharge. Thus prudent measure has to be adopted for adequate water use per head as population increase and demographic change will exacerbate more stress on the availability of this precious resources aside the climate change impact. The implication is that further proliferation of borehole wells will deplete the entire aquifer and subject it to be devoid of manageable storage capacity, particularly in the crystalline aquiferous units. It is clear that, if conceptual hydrogeological modelling of the catchment is well known and reliable data are obtained, the MWB method gives accurate results in the basins. However, comparison of multiple methods is valuable for determining the plausible budget amount and for highlighting the uncertainty of the estimate.