Sea Water Intrusion in a Coastal Aquifer: A Case Study for the Area Between Seeb and Suwaiq, Sultanate of Oman

Abstract

The Batinah Coastal plain, located between the Hajar mountains and the sea, from Muscat to the UAE border, is a favorable region for groundwater occurrence in Oman and the main source of fresh water in this coastal area. The coastal parts of the Batinah plain, particularly Barka and Suwaiq, have suffered from groundwater deterioration over the past 20 years. This paper reviews the monitoring activities of groundwater electrical conductivity in the Batinah coastal plain between Seeb and Suwaiq over the period 1984 to 2005, an area of approximately 394 km2. GIS and Auto-Cad techniques were applied to illustrate different salinity zones as the wells coordinates and their field EC were digitized on maps with contours. Zones of salinity ranges are identified and their areas were computed and compared to the total catchment area of each wadi. All samples were collected from the same upper gravel layer, ranging in depth 20-100 meters. There has been a substantial deterioration in water quality as indicated by a 7% reduction in areas of water suitable for agriculture use (2.000 – 6.000 μS/cm), reflecting a loss of 2,714 hectares of irrigated land. Also, a saline interface is reported 12 km inland at Wadi al Taww, Barka area, an indication of aquifer over-exploitation. It is therefore critical that monitoring of water quality and quantity is continued. It is recommended to improve implementation of the standard water resources management solutions to coastal aquifer saline contamination. Cooperation of different organizations and water users is essential to conserve these precious water resources.