Multi-layer groundwater flow simulation in Al-Khoud lower catchment in Oman

Sustainable groundwater resource management requires a better understanding of multilayer interactions, caused by the heterogeneous formations and enhanced by the groundwater withdrawal in aquifers. This phenomenon was studied in Al-Khoud lower catchment in Oman. Water exchange between different layers was observed by measuring piezometric heads of wells located at the same place with screen intervals placed in different layers. In addition, groundwater levels from 8 more wells and pumping rates from 60 wells were used for developing a numerical model in a 156 km(2) area. Lithological data from 23 boreholes were used for defining three subsurface layers. Model results under different conditions indicated that 1.9-3.8 m head difference could be attributed to the pumping, while 2.1-6.0 m groundwater-level variations were accounted for the heterogeneity and anisotropic effects. Further analysis showed that the increased pumping rate increased the piezometric head difference between the layers, which enhances the multi-layer interactions.