1.1.1.WATER RESOURCES Total annual surface runoff is only about four million m3 and there are no rivers, perennial streams or lakes. There are also no dams. Bahrain receives groundwater by lateral under-flow from the Damman aquifer, which forms only a part of the extensive regional aquifer system (the Eastern Arabian Aquifer). This aquifer extends from central Saudi Arabia, where its main recharge area is located at about 300m above sea level, to eastern Saudi Arabia and Bahrain, which are considered the discharge areas. The rate of groundwater inflow has been estimated at about 112 million m3/year under steady-state conditions (before 1965) and this figure is considered to be the safe groundwater yield in Bahrain. But groundwater reserves suffer from severe degradation, in terms of both quality and quantity, as a result of over-extraction and seawater intrusion.

1.1.2.WATER USE Historically, Bahrain has utilized groundwater for both agricultural and municipal requirements. Natural freshwater springs used to flow freely in the northern part of Bahrain and before 1925 the water supply depended on these springs and some hand-dug wells, the total discharge of which was estimated at 93 million m3/year. With increased water demand after the exploration of offshore reservoirs of crude oil and gas in 1946, spring flow decreased and water started being pumped from boreholes. During the 1980s, most of the springs ceased flowing, and increased demand for water caused deterioration in water quality, including the intrusion of seawater into the aquifer system (UNU, 1995). In 1988, groundwater use in Bahrain was estimated to be 153 million m3/year, including 138 million m3 of tube-well abstraction, 8.1 million m3 of water from land springs, and 6.6 million m3 of water from marine springs. In 2003, total water withdrawal in Bahrain was 357.4 million m3. The part used for irrigation and livestock watering purposes dropped to 45 per cent, from 56 per cent in 1991. Total annual water demand was met by three sources: primary groundwater (238.7 million m3), desalinated water (102.4 million m3) and treated sewage effluent (16.3 million m3). This means that nonconventional water sources accounted for 34 per cent of total water withdrawal in 2003. About 90 per cent of the water used in agriculture, including livestock, was primary groundwater and 10 per cent treated wastewater. For municipal and industrial purposes, about 48 per cent of the water used was primary groundwater, and the remaining part was desalinated water. The total freshwater withdrawal (primary groundwater plus reused treated wastewater) represented 220 per cent of the total renewable water resources in 2003, meaning that abstraction of fossil water and groundwater mining was taking place. The excessive pumping of groundwater caused a sharp decrease in groundwater storage and a reduction in potentiometric levels of about 4m between 1965 and 1992. As a result, more than half the original groundwater reservoir has been completely degraded due to seawater intrusion and saline water up-flow from the deeper zones. The annual extraction is almost twice the annual recharge, leading to an everincreasing groundwater deficit. While the average annual groundwater depletion over the period 1965-1992 was approximately 40 million m3, in 1991/92 it was over 96 million m3. In 2003, the total quantity of desalinated water used was 102.4 million m3, against 44.1 million m3 in 1991. In 2005, treated wastewater amounted to about 62 million m3/year of wastewater (secondary treatment), against about 45 million m3 in 1991. Despite an increase of 100 per cent compared with 1991, only 16.3 million m3/year received tertiary treatment; part was used for irrigation purposes in government farms and some private farms, while the rest was discharged to the sea. The chemical and hygienic properties of the tertiary treated water are within international limits and are considered good for agricultural purposes. Although the government has plans for the full utilization of Treated Sewage Effluent (TSE) water through major agricultural projects, delays and lack of funds for these projects have limited the use of these waters. According to Arabian Gulf University academic affairs vice-president Professor Waleed Al Zubari at the 18th GCC-Japan Environment Symposium and Second Joint Bahrain Centre for Studies and Research (BCSR) – Japan Co-operation Centre Petroleum (JCCP) Environment Symposium in February 2010, 66 per cent of Bahrain’s water supply comes from non-renewable groundwater, 29 per cent from renewable desalination plants and the rest from waste and used water. In Bahrain, 45 per cent of water is used for agriculture, 49 per cent for domestic use and 6 per cent for industry.

1.2.WATER QUALITY, ECOSYSTEMS AND HUMAN HEALTH Over-utilization of the Dammam aquifer, the principal aquifer in Bahrain, by the agricultural and domestic sectors has led to its salinization through water coming from adjacent brackish and saline water bodies (particularly from the underlying saline aquifer of Umm er Radhuma). A hydrochemical study identified the locations of the sources of aquifer salinization and delineated their areas of influence. The investigation indicates that the quality of aquifer water quality has been significantly modified as groundwater flows from the northwestern parts of Bahrain, where the aquifer receives its water by lateral underflow from eastern Saudi Arabia, to the southern and southeastern parts. Four types of salinization of the aquifer have been identified: -brackish water up-flow from the underlying brackish water zones in north-central, western, and eastern regions; -seawater intrusion in the eastern region; -intrusion of sabkha water (saline water from saline areas) in the southwestern region; Country Overview - Bahrain -irrigation return flow in a local area in the western region. Four alternatives for the management of groundwater quality are under discussion by the water authorities in Bahrain. Priority areas have been proposed based on the type and extent of each salinization source, in addition to groundwater use in that area. Simulation modelling could be used to evaluate the effectiveness of the proposed management options in controlling the degradation of water quality in the Dammam aquifer (Zubari, 1999). Since it has become the policy to curb the abstraction of groundwater resources in the Damman aquifer and to improve its quality, further development of water sources will undoubtedly involve desalination, either by a thermal process or reverse osmosis. The choice will depend on sitespecific conditions and economy or cost. The first multi-stage flash (MSF) seawater desalination plant was introduced in Bahrain in 1976. The use of reverse-osmosis (RO) desalination for saline groundwater on Bahrain Island began in 1984-1986. One of the world’s largest RO plants for the treatment of saline groundwater, located 25 km south of the capital of Bahrain at Ras Abu-Jarjur, was commissioned in 1984. The plant has an installed capacity of 45 500 m3/day and its source of raw water is the highly saline brackish groundwater in the Umm er Radhuma formation. The RO plant was designed to meet the domestic water demand of Manama city, taking into account its advantages over an MSF plant, such as short construction time, lower energy cost, ease of operation and maintenance (UNU, 1995). In 2002, the total installed gross desalination capacity (design capacity) in Bahrain was 500259 m3/day (Wangnick Consulting, 2002). The reuse of treated wastewater for agriculture and landscape irrigation started in 1985. The main wastewater treatment plant in Bahrain is the Tubli Water Pollution Control Centre (Tubli WPCC), which in 2005 was producing about 160,000m3/day of secondary treated effluent, and around 60,674m3/day received tertiary treatment. There are also eleven minor wastewater treatment plants with a total designed capacity of about 9,720m3/day. Treated sewage effluent was expected to reach 200,000m3/day, or 73 million m3 per year, by 2010 (Al-Noaimi, 2005). The additional amount treated, if properly used for irrigation, was expected significantly to reduce water extraction, reserving the limited freshwater resources for potable supply and other priority uses. In Bahrain the cost of tertiary treated effluent is about US$0.317/ m3, while the cost of desalinated water is about US$0.794/ m3 (FAO/WHO, 2001).