1.1.1.WATER RESOURCES Estimated total internal renewable water resources stand at 1.4km3/yr. About 1.05km3 is surface water and 1.3km3 of groundwater, while 0.95km3 is considered to be overlap between surface and groundwater. There are several important aquifers in Oman. The main aquifer systems include the alluvial aquifers, the regional quaternary aquifers, the aquifers of the Hadramawt Group and the aquifers of the Fars Group. Some of these aquifer systems are part of large regional aquifers that extend throughout the Middle East. Fresh groundwater is mostly available in the northern and southern extremities of Oman where precipitation and recharge occur. Most of the groundwater in other areas is brackish to saline. There are several hundred springs in Oman and most of them are in the mountainous areas. The discharge, temperature and water quality of these springs varies. The main reliable source of water is internal groundwater. In nearly all wadis surface water runoff only occurs for some hours or up to a few days after a storm, in the form of rapidly rising and falling flood flows. Exceptions are some significant wadis like Dayqah and Quriyat that have an average flow of 60 million m3/yr, or Halfayn which covers a catchment area of 4,373 km2. Since the infiltration capacity of coarse alluvium and fissured rock is high, groundwater can be recharged quite easily. Oman has large amounts of water in aquifers that were replenished a long time ago when wet climate conditions prevailed. Present recharge is very low, if any. These non-renewable resources are in the Dhofar (Najd), Al Dahra (Al Massrat) and Sharqia (Rimal al Sharqia) regions. The government decided to use these aquifers to supply water for urban use and as a reserve for the future. Since 1985, 31 major recharge dams have been built together with many smaller structures to retain a portion of the peak flows, thus giving more scope for groundwater recharge. In 2006, the total dam capacity was 88.4 million m3. Desalination plants make an important contribution to water supplies where natural water resources are inadequate. Sea water desalination in Oman started to supply potable water to Muscat and the coastal area in the early 1970s. In 2002, the total installed gross desalination capacity (design capacity) was 322,579 m3/day or 118 million m3/yr. Total production is around 109 million m3/yr (2006), whereas it was 34 million m3 in 1995. The desalination plants should provide 80 per cent of the potable water supply. In 2000, total wastewater produced was 90 million m3. In 2006, 37 million m3 was treated and reused. The use of treated effluent is limited to landscape irrigation using sprinkler, drip and bubbler systems. The Muscat Municipality has major plans to extend its sewage collection and treatment system. At present, total water treatment in the municipality is about 25,000 m3/day, but in the near future 70,000 m3/day should be generated. There are treatment plants in each region. The recent water treatment station built in Salalah city (south of Oman) will produce about 40,000 m3/day. The effluent undergoes an effective tertiary treatment, one of the best in the world according to standards in this field.

1.1.2.WATER USE In 2003, a total of 13.21 million km3 of water was withdrawn, of which 88.4 per cent was for agriculture, 10.1 per cent for municipal purposes and 1.5 per cent for industry. The water balance shows that in many areas demand for water exceeds natural replenishment. For instance, in coastal areas, overwithdrawal has led to saline water intrusion and deterioration in water quality. At present, groundwater depletion is estimated at around 1.34 million km3/yr. As traditional water structures, the Al Zaijrah and Birkat systems have a particular importance in Oman. Al Zaijrah is a system in which water is extracted from a dug well, originally by using animals. This was the main traditional method of lifting water for agriculture from dug wells until the introduction of pumps in the 1950s. The Zaijrah consists of one or two Manjur (well-wheels) made from individual wedge-like sections of acacia wood, which are fitted around a central hub and bound tightly with strips of leather or shark skin. A Birkat is a cistern, which is a traditional system designed to collect and store rainfall-generated flows. It comprises an excavated chamber or a naturally occurring hollow structure. For centuries the use of birkats has been vital for the survival and development of many remote settlements in the Musandam peninsula, where they serve as the only source of water to meet domestic and livestock needs.