Evaluating the effects of managed aquifer recharge using the MODFLOW model: A case study of the gash aquifer, Kassala, Sudan

Abstract

Study region: The Gash aquifer, located in the drought-prone Kassala region of eastern Sudan Study focus: Groundwater resources face growing global threats from over-extraction, limited recharge, and climate change—especially in arid and semi-arid regions like Kassala—highlighting the need for sustainable management approaches. Managed aquifer recharge (MAR) is a promising strategy to mitigate groundwater depletion. This study evaluates the effects of MAR using a numerical groundwater flow model developed in MODFLOW through Processing MODFLOW (PMWIN), calibrated over a nine-year period (2008–2017) using data from the Directorate of Groundwater, Kassala. The model simulates three MAR scenarios targeting different zones of the Gash aquifer: upstream (Scenario 1), central Kassala (Scenario 2), and downstream (Scenario 3). New hydrological insights for the region: Scenario 2 produced the most significant improvements in groundwater levels, with spatial variations based on recharge location. The total volume required for artificial recharge—defined as the annual gap between groundwater demand and the lowest recorded natural recharge—was estimated at 109 million m³ annually. An average annual recharge of 19 million m³ would stabilize groundwater levels to those observed in June 2017. Without intervention, groundwater levels may decline by about 20 m by June 2045, particularly in northern Kassala. These findings emphasize the importance of optimal recharge placement for sustaining groundwater resources. These insights support MAR planning in similarly arid, water-stressed regions.

Keywords

• Artificial recharge
• Modflow model
• Drought
• Gash aquifer
• Sudan