Journal of Arid Environments (2001) 48: 419–428 doi:10.1006/jare.2000.0753, available online at http://www.idealibrary.com on Water quality and invertebrate fauna of farm wells in an area affected by salinization in Oman Reginald Victor & Amina A. I. Al-Farsi Department of Biology, College of Science, Sultan Qaboos University, P.O. Box 36, Postal Code 123, Sultanate of Oman ( Received 22 February 2000, accepted 6 October 2000) 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.  2001 Academic Press Keywords: Arabia; farm wells; groundwater; invertebrates; irrigation; Oman; salinization; species diversity; water quality Introduction The Sultanate of Oman in Southern Arabia receives 2·0 km 3 year 1 of renewable freshwater with 0·48 km 3 of annual withdrawal and the agricultural sector uses 94% of the total freshwater withdrawn (Gleick, 1993). Up to 25 years ago a coastal strip bordering the Gulf of Oman, in the Wilayat of Sur, the Sharqiyah (eastern) region supported a productive green agriculture. The agricultural lands started from about 2 km of the shoreline and extended inland. Since the early 1970s, the over-extraction of groundwater for irrigated agriculture has led to a rapid increase in the salinity of groundwater. As a result, several farms closer to the coast were abandoned, as far back as 20 years ago. Recently, many inland farms are being abandoned and some others are unable to support the cultivation of fruit, vegetable and fodder crops. Even the most salinity tolerant date palms (Landon, 1991) that thrive when all other crops fail are suddenly declining in number in many farms. The spreading inﬂuence of salinity stress inland has been alleged as the reason. 0140}1963/01/070419#10 $35.00/0  2001 Academic Press