Modelling the risk of water table rise from dam seepage in arid urban areas: lessons learned from Al-Jifnain dam operation

The global phenomenon of water table rise (WTR) presents significant environmental challenges, particularly in arid and semi-arid regions lacking adequate stormwater infrastructure. In Oman, a prolonged WTR occurrence at Sultan Qaboos University (SQU) has raised concerns about subsurface and surface infrastructure stability. The imminent operation of Al-Jifnain dam is projected to intensify groundwater levels, increasing the risk of waterlogging that could affect building foundations, utilities, and vegetation. To assess the impact of seepage from the dam’s reservoir, a multi-scale groundwater–vadose zone modeling approach was applied. A 3D stratigraphic model of five hydrogeological units was constructed from 108 boreholes. Using MODFLOW-USG with a Smoothed Octree grid, the model was calibrated and validated. Results indicate groundwater mounding up to 4 m at the dam and 0.5 m–2 km downstream. HYDRUS2D simulations confirmed elevated waterlogging risks, compounded by the limited effectiveness of the cutoff wall and the inferred dissolution of caliche layers under increased freshwater infiltration.