Water quality and invertebrate fauna of farm wells in an area affected by salinization in Oman

The spreading influence of salinity stress on the farmlands of coastal strip in the Wilayat of Sur, Sharqiyah region was investigated. A 4-km study transect was chosen from 2 km from the coast to 6 km inland and three zones based on farm conditions were demarcated. Within each zone three farms were randomly chosen and a total of nine farm wells were studied. Irrigation water quality clearly indicated that Zones 1, 2 and 3 could be classified as high, intermediate and low salinity zones. The improvement of water quality from high to low salinity zones was progressive and statistically significant. Seawater intrusion appears to be the cause of degradation in water quality. Irrigation water quality of high and intermediate zones was unacceptable by international standards. Expansion of farms, increased water extraction and a recharge dam upstream are all considered as factors promoting salinization. Management strategies for combating salinization are discussed. The invertebrate assemblages of the study wells have been described and the potential of some sensitive species for use as indicators of salinity stress is revealed. However, practical difficulties warrant the continued use of chemical methods to monitor salinity changes.