Coastal salinization: A case history from Oman

Nearly half the agriculture in the Sultanate of Oman is concentrated along the coastal strip of the Batinah Plain. Arid tropical conditions and the absence of surface water create total dependence upon groundwater withdrawal from wells. The initial equilibrium groundwater conditions were upset, first by the transition from animal bailed to pumped wells, and subsequently by agricultural expansion and increasing urban and industrial water demands. The consequent effects of saline upconing and intrusion have been monitored in selected areas by repeated electrical conductivity surveys over a 9-year period. Despite an apparent excess of fresh water in the Wadi Semail catchment, locally severe salinization has occurred, mainly due to heterogeneous aquifer conditions, thereby detracting from the benefits of agricultural expansion. In the Wadi Rusayl catchment excess of extraction over recharge has resulted in severe salinization. The situation will probably deteriorate further unless rigorous conservation measures and enhanced aquifer recharge are implemented. In such sensitive coastal areas, even if a catchment water balance has ‘excess’ groundwater flow seaward, the local subcatchment response may involve a high salinization risk. Therefore if groundwater extraction is to be increased, the water balance alone may be an insufficient basis for water resources management. The effects upon ‘high risk’/interfluvial areas should also be taken into account.