Using MODFLOW to investigate the effect of persistent water deficit in Al‑Jizi coastal aquifer, Sultanate of Oman

Groundwater is the principal water resource in the Sultanate of Oman and its management is critical to the country’s current development as well as those of future generations. Groundwater aquifers are under continuous threat due to overuse in the arid and semi-arid countries having lack of surface water sources and rainfall. Proper management of groundwater resources requires estimation of aquifer properties and groundwater abstraction rate. To study an important coastal aquifer in Wadi Al-Jizi in Al-Batinah region that happens to be the most important agricultural region in Oman, a three-dimensional groundwater flow model (MODFLOW) was employed to simulate the groundwater flow. The hydraulic conductivity and vertical anisotropy of the two-layer model were calibrated using observed values of the year 2000 in steady-state condition. Sensitivity analysis was conducted for the hydraulic conductivity of both the layers affecting the water level in the model domain. A set of 9 observation wells scattered over the aquifer were used in the calibration. After the validation under steady flow conditions, the model was validated in the transient state from the year 2000 to 2017 and a good agreement was found. The predictions of groundwater elevations were made using the validated model until year 2040 under various pumping rate scenarios. Results showed that if the pumping rates were increased by 30%, the decline of water table could reach 4 m at some places. The results of this study could be useful for the consulting engineers and public authorities for an efficient management of groundwater resources in Wadi Al-Jizi coastal aquifer.

© 2022, Saudi Society for Geosciences.