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4 Hydro-powered reverse-osmosis desalination in water-resources planning in Jordan

4.1 Background and objectives
4.2 The water resources of Jordan
4.3 Water-resources development and management
4.4 Non-conventional water-resources development
4.5 Case study on hydro-powered brackish-groundwater desalination by reverse osmosis: A proposal for co-generation in the Disi-Aqaba water supply scheme
4.6 Non-conventional water-resources development in the national water master plan of Jordan

4.1 Background and objectives

4.1.1 Background

Jordan is located to the north-west of the Arabian peninsula and extends from 29 to 33 north latitude and from 35 to 39 east longitude, with an area of 89,555 km (fig. 4.1).

More than 80% of the country is covered by almost unpopulated desert. The population was estimated to be about 2.8 million in 1985, about 90% of whom live in the north-west quadrant of the country. Greater Amman, which is a metropolitan district within a 30 km radius from the centre of Amman city, occupies 3% of the area of the country, but its population is as much as 1.62 million (573 people per km), or about 60% of the whole population of Jordan. The national population growth rate was about 3.7% per year in the 1970s (Huang and Banerjee 1984), mainly due to migration from the West Bank and the Gaza Strip.

The population growth rate is expected to decline slowly to about 3.2% by the year 2010. Municipal and industrial water use is expected to increase from 24% of total water use in 1985 to 30% in 2005 and 45% in 2015, assuming a modest consumption rate of 83 litres per capita per day for domestic use. The national water demand was simply projected to increase to 1,209 million m per year by the year 2000, assuming a growth rate of 2.5%-3.5% in population, 5% in industrial uses, and 4% in agriculture uses (MPJ 1990). Effective rainfall as the potential renewable water resource was estimated to be 1,123 million m per year, with 245 million m becoming groundwater and 878 million m running off as surface flow (World Bank 1989).

Fig. 4.1 Jordan and Israel

Limitations of water, one of the important resources of Jordan, are likely to have a major impact on the economic development of the country. By the year 2000 most of the conventional water resources in the country will have been fully exploited by conventional measures such as constructing dams and drilling wells. The development of marginal non-conventional water resources will therefore become a key measure in the twenty-first century for sustaining economic development.

Non-conventional water in Jordan consists primarily of brackish water, seawater, and reclaimed urban waste water. In the 1970s it was considered that large-scale seawater desalination projects would become both technically feasible and economically viable as water supply alternatives in the early 1990s (Buras and Darr 1979). Innovative research in 1980s on membrane technologies for desalination has been changing the world market by reducing the share of conventional MSF distillation, which has so far been the only method used in Middle East countries (see Appendix A). The development of saline water resources by desalting with reverse osmosis and other membrane processes will play an increasingly important role in the context of the national water master plan.

4.1.2 Objectives

The main purpose of studying the application of hydro-powered RO desalination in a case study on the Aqaba-Disi groundwater development and water supply project is to evaluate the technical feasibility and costeffectiveness of the proposed co-generation system.

The proposed co-generation system aims not only to conserve the fossil groundwater resources in the Disi aquifer but also to retrieve the hydropotential energy in a pipeline system for both the generation of electricity and desalting brackish groundwater from the Kurnub aquifer.

Potential non-conventional water-resource applications such as the proposed hydro-powered RO desalination are examined in the context of the national water master plan for sustainable development in Jordan in the twenty-first century.

4.2 The water resources of Jordan

Hydro-meteorologically, Jordan is semi-arid to arid, with relatively abundant water resources as compared with other states in the Middle East such as Kuwait. About 80% of its territory is steppe and desert where water is only minimally available. Jordan, however, has various sources of water, such as rivers and streams, springs, wadi flash floods, renewable and non-renewable groundwater, and reclamation of treated sewage effluents.

4.2.1 Water-resources potential

Water resources in Jordan depend mainly on precipitation within the country, except for the Yarmouk River, whose flow is mainly fed by rainfall on Syrian territory. Average rainfall ranges from 600 mm per year in the northern uplands to less than 500 mm per year in the southern and eastern desert areas. The rainfall occurs between October and May, and is at its height between December and March, when over 80 % of the annual rainfall occurs.

The average annual volume of rainfall within Jordan has been estimated to be 8.5 x 109 m. However, with high evaporation losses, the average net annual yield is only about 1.12 x 109 m (13%), with 875 million m (10%) in the form of surface water and 242 million m (3%) in groundwater (Huang and Banerjee 1984). About two-thirds of Jordan's potential usable water resources is surface water. About 400 million m per year of the surface flow, which is 46 % of the total runoff, forms the discharge in the Yarmouk River. Sustained-yield and/or renewable groundwater resources are preliminarily estimated at 3% of the annual rainfall; their recharge is mostly dependent on rainfall on the western highlands. In addition, it is estimated that over 11 x 109 m of stored fresh groundwater exists within the state, but this is mostly non-renewable groundwater which may offer opportunities for short-term and emergency uses.

4.2.2 Surface water resources

Surface water resources, which constitute two-thirds of Jordan's potential usable water resources, are at present used exclusively for agriculture, except for spring water, which is sometimes collected for municipal use. Most of the municipal water supply systems and industries in Jordan at present depend on groundwater and springs. Although surface water resources exist on the northern border such as in the Yarmouk River, in the Jordan valley, and in some of the wadis flowing into the Jordan River, exploitation of surface water for municipal and industrial water supply has not so far occurred to any great extent because of sporadic flow patterns, priority use for irrigation, relatively low elevation, and the long distances to population centres.

River flows are generally of a flash-flood nature, with large seasonal and annual variation. Annual base flows, moreover, whose volume is estimated at 540 million m, vary by at least 15%-20%, depending on rainfall patterns with a return period of five years (Huang and Banerjee 1984). The base flow of 150 million m per year in the Yarmouk River has been developed by the East Ghor Main Canal (EGMC) irrigation project since 1965. Corresponding to the rapid increase in water demand in the metropolitan area, 45 million m of canal water has been diverted from the EGMC to Amman for municipal and industrial use by constructing a treatment plant and pipeline with a total difference (pumping) head of 1,300 m.

Since the beginning of the 1960s, a number of storage dams have been constructed that together hold an estimated 452 million m of water. The AlWuheda dam, which is being built on the Yarmouk River near the Syrian border to store 225 million m, will supply irrigation water for downstream in the Jordan valley and will generate electric power. Syria will use part of the water and 75% of the total hydroelectric power (World Bank 1988).

4.2.3 Groundwater resources

Major potential aquifers are found in the pervious sequences in the basalt system of the Pleistocene, the Rijam (B4) formation of the Lower Tertiary, the Amman-Wadi Sir (B2/A7) formation of the Upper to Middle Cretaceous, the lower Ajlun (A1-6) formation of the Middle Cretaceous, the KurnubZarqa formations of the Lower Cretaceous, and the Disi formations of the Palaeozoic age.

The shallow aquifer systems of basalt-Rijam (B4) form a locally important aquifer in the central part of the Jafr and Al-Azraq-Wadi as-Sirhan basins. Groundwater irrigation has been practiced in and around the town of Jafr since the 1970s, but the underlying aquifer B4 has been contaminated by stages by irrigation return flows, increasing salinity (TDS) from 500 mg/l to 4,000 mg/l, during the ten years of operation. The sustained yield is estimated to be less than 2 million m per year, because of the limited groundwater recharge through the wadi beds during the occasional flash floods. The basalt-Rijam system in the Azraq basin has been intensively exploited for the purpose of Amman municipal water supply. Annual abstraction from the Azraq wellfield reached 15.6 million m in 1985, which exceeded the safe yield, lowering the piezometric head and increasing water salinity. Groundwater in the Sirhan basin, of which the recharge mechanism is the same as that of the Jafr basin, is untapped.

The most important aquifer system is the Amman-Wadi Sir (B2/ A7), which consists of limestone, silicified limestone, chert, sand limestone, and sandstone of Upper to Middle Cretaceous age. This system extends throughout the entire country with thicknesses of about 100350 m. The depth of the groundwater table below ground level generally ranges from 50 to 250 m in the uplands. Good groundwater recharge occurs from the western highlands, where the annual rainfall ranges from 200 to 600 mm. To the east, the aquifer is confined by thick marl such as the Muwwaqar (B3) formation, and water salinity is high. This economic aquifer system, B2/A7, has been excessively exploited in the northern part of the country, lowering the piezometric levels and causing deterioration in water quality. In the southern part of the country such as the Mujib basin, the Upper Hasa basin, and the Jafr basin, the B2/A7 aquifer is the most important economic aquifer, of which the quality is as good as less than 500 mg of TDS per litre. The groundwater is being pumped for M&I water supply from the wellfields of Qastal, Siwaqa, Qatrana, Sultani, Karak, Shoubak, and Hasa.

An intermediate aquifer system is the lower Ajlun (A1-6), which consists of alternating limestone, marl, shale, chert, and sandstone of Middle Cretaceous age. This system is underlain by the Amman-Wadi Sir (B2/A7) formation, which is mostly confined by its relatively impervious layer of marl and shale in the A5/6A or upper unit of A1-6. The lower Ajlun formation extends throughout the country with variable thickness and litho-facies. Southwards, aquifers in the lower Ajlun formation become more sandy, and salinity becomes as little as 350 mg of TDS per litre. The aquifer system is mostly untapped, however, because of its complicated hydrogeology and deep formation.

Deep sandstone aquifers are the Kurnub/Zarqa of Lower Cretaceous age and the Disi of Palaeozoic age, which are unconformably separated by a less permeable layer of sandstone, siltstone, and shale. The Kurnub formation intercalates frequent argillaceous layers in the south, while the Disi is composed of massive and rather homogeneous arenaceous layers. Groundwater in these aquifers is mostly non-renewable because of limited groundwater recharge through small outcrop areas. The quality of the groundwater in the Kurnub-Zarqa system varies from fresh to brackish. Excellent quality with low salinity, however, is found in the Disi aquifer in the southern part of the country, which has been exploited for the water supply of Aqaba and local experimental irrigation. The development potential of Disi groundwater has been estimated to be about 100-200 million m per year for a period of over 50-100 years. The aquifer complex, however, forms a huge groundwater reservoir extending under the whole of the country. This groundwater storage offers opportunity for short-term and emergency uses.

Groundwater is presently used for municipal, industrial, and agricultural purposes. In the northern uplands, which include the heavily populated Greater Amman and Irbid areas, groundwater in the Amman-Wadi Sir aquifer has been over-exploited in the 1980s. Significant irrigation water use is also found in the Zarqa River basin, where about 70% of the water is from groundwater. Abstraction in the northern uplands is estimated at about 120 million m per year against an estimated sustainable yield of 90 million m per year.

It is said that 96% of the kingdom's population is now supplied with drinking water from springs and groundwater wells. A series of water supply schemes have been carried out, including the following groundwater projects-the Wadi Arab scheme west of Irbid (20 million m per year), the Azraq project (15 million m), the Amman-Zarqa project, (14 million m), the Qatrana-SiwaqaQastal project (9 million m), the Sultani project near Karak (3.5 million m), the Shoubak project (1.5 million m), and the Disi project (17 million m)-and the Deir Alla-EGMC pipeline project (45 million m) (World Bank 1988). The Mukheiba wellfield (26 million m per year), which was developed for irrigation water supply downstream of the Yarmouk/Ghor, will be diverted to upland water supply by taking advantage of the difference in the water head of about 200 m between the artesian wellfield and the Ghor.

4.2.4 Treated sewage effluents

Significant work on sewerage has taken place during the last decade, and about 40% of the urban population (25 % of the country's population) is now being served. In many urban areas, however, household cesspits and septic tanks are still commonly used, with liquid effluents discharging into the soil via open-joint pipes or openings in pit wells. This return flow mixes with groundwater recharge from rainfall, which is reused for water supplies, and incremental increases in mineral content and high nitrate concentrations have been monitored in the groundwater under some densely populated areas.

Groundwater in the Wadi Arab wellfield, which draws from the AmmanWadi Sir aquifer (B2/A7), was contaminated by direct infiltration from sewage effluents in 1988 through an outcrop of B2/A7 in the upstream area. Drainage of sewage effluents from Irbid city was diverted to the north to protect the quality of groundwater in and around the outcrop area of the B2/A7. Direct recharge of sewage effluents into the limestone aquifers is not planned.

The Zarqa River, which runs through the heavily populated cities of Amman, Zarqa, and Ruseifa, collects the return flows of sewage efffluents. The sewage effluents mix with surface water in the river system and are stored in the reservoir of King Talal dam, which is used exclusively for irrigation water supply in the Jordan valley downstream and not for municipal water supply.

4.3 Water-resources development and management

The United Nation's partition proposal of 1947, which divided Palestine into Jewish and Arab states, ignored water problems. The 1948 Arab-Israeli war aggravated the difficulties of cooperative water development and management. The failure of negotiations to develop a multilateral approach to waterresources development and management reinforced unilateral action. Though the Unified Plan (see Appendix C) was not ratified, both Jordan and Israel undertook to operate within their allocations. Their two major projects undertaken were the Israeli National Water Carrier and Jordan's East Ghor Main Canal.

The design of the East Ghor Main Canal (EGMC) was begun in 1957; its construction began in 1959, and the first phase up to Wadi Zarqa was commissioned in 1966. The King Talal dam, situated on the Zarqa River, with a storage capacity of 56 million m, and an 18-km extension of the EGMC were completed in 1977 at a cost of US$52 million (fig. 4.2).

Smaller dams were built on the rift-side wadis from the late 1960s, including the Kafrain dam (3.8 million m) and the Wadi Ziqlab dam (4.3 million m). The rift-side dam scheme on the Wadi Shueib was intended to store winter flows for downstream irrigation; however, it could not effectively store the design volume, owing to substantial leakage through a gravel formation and limestone geology in and around the reservoir. The reservoir has never been filled with water up to the design high-water level since the completion of the dam.

Fig. 4.2 Water resources system of Jordan

The Wadi Arab dam, completed in 1987, has a total storage capacity of 20 million m and cost US$50 million.

Present surface water consumption is estimated at 336 million m per year, almost all of which is for irrigation, including approximately 102 million m for upland irrigation and 229 million m for irrigation in the Jordan valley. Of this, approximately 110 million m is diverted from the Yarmouk River through the EGMC, and about 119 million m comes from the rift-side wadis.

Owing to topographic and hydro-geotechnical problems, the construction of storage dams in Jordan is extremely costly. New investment in storage dams in Jordan can be justified only for the supply of municipal and industrial water or for the irrigation of high-value, highyielding crops using water-conserving technologies.

The water shortage in Jordan is most noticeable in domestic use. The Deir Alla pumping station, which has an installed capacity to pump, treat, and convey 45 million m of water per year from the EGMC, was completed in 1988. The scheme involves pumping water up about 1,300 m, and the operating costs are excessively high to sustain the quality for drinking purposes. Due to priority use in the irrigation sector, the system is not allowed to supply precious water during the summer season, and consequently only about 28 million m of water are being pumped a year.

The government strategy up to the present has been to use groundwater resources for both M&I and agriculture use, and to use surface water primarily for irrigation. Domestic water supply depends exclusively on the groundwater supply, owing to its better quality and the higher elevation of the water body than that of the surface water resources. Groundwater pumping amounted to 155 million m per year in 1985, which exceeded the safe yield in some wellfields, including the Amman-Zarqa aquifer. Almost all the renewable groundwater resources have been excessively developed, lowering the piezometric level and causing deterioration in the quality of water in some aquifer systems. The Disi is the only remaining significant aquifer. It is, however, a fossil aquifer, with an estimated safe yield of about 110 million m per year over a 100-year period.

When Jordan's last major potential water sources, Disi groundwater and the Al-Wuheda dam, are fully developed, there will be no alternatives except the use of non-conventional water resources and/or importation of water from other countries.

4.3.1 Surface water resources

Surface water resources are dominated by the Yarmouk and Zarqa Rivers, which provide the majority of the irrigation water for the Jordan valley. Irrigation in the Jordan valley in the past has been made possible only by largescale public investments in water diversion such as the East Ghor Main Canal and water storage dams, including the King Talal and the Wadi Arab, to utilize the potential of surface water resources. The King Talal dam on the Zarqa River was completed in 1979 to collect not only natural flows in the river system but also sewage effluents, both treated and untreated, from the population centres of Amman and Zarqa. Sewage effluents constitute an increasing proportion of the water stored behind the dam, and the amount of treated sewage in northern Jordan is expected to increase from 29 million m in 1985 to 116 million m in 2005 and 165 million m in 2015 (World Bank 1988). Although the water quality of the reservoir is still good and suitable for the cultivation of most crops through drip irrigation except for leafy vegetables, use of King Talal water for M&I, even after treatment, has to be avoided on account of the health risks.

Small dam schemes have been implemented to provide embankment dams with heights of 30-38 m on small streams in the rift-side wadis, including the Ziqlab (4.3 million m of storage), the Shueib (2.3 million m), and the Kafrain (3.8 million m) since 1968. As mentioned earlier, the dam on the Wadi Shueib was intended to store winter flows for downstream irrigation, but it could not effectively store the design volume owing to substantial leakage through the gravel foundation and limestone geology in and around the reservoir.

The Wadi Arab dam was originally planned to store 30 million m of spring flow per year. However, the flowing spring suddenly stopped because of groundwater development in the adjacent wellfield in the wadi in 1985. The dam design had to be amended to store increased winter flow from the EGMC by pumping up 100 m for M&I water supply during the summer season. This was made possible by raising the dam height and changing the supply objectives, including the M&I use. The combined capacity of the King Talal and Wadi Arab dams was increased to 130 million m when the dam heights were raised at the end of the 1980s.

WATER-RESOURCES DEVELOPMENT TN THE YARMOUK BASIN The Yarmouk River, which has a mean discharge of 400 million m per year, provides almost half of Jordan's surface-water resources. The water in this river, after allowing some 17 million m per year for downstream users in neighbouring countries, is diverted through the EGMC, an irrigation canal that runs along the Jordan River to serve agricultural water needs in the Jordan valley. The shortage of groundwater resources to meet growing municipal and industrial water demands in north Jordan has required the conveyance of 45 million m of water per year from the EGMC to Amman by pumping an extremely high head of 1,300 m from the Deir Alla treatment and pumping station (200 m below sea level) to the terminal reservoir (1,100 m above sea level). The schematics of water-transport systems in north Jordan are shown in fig. 4.3.

THE AL-WUHEDA (MAQARTN) STORAGE DAM SCHEME. The AlWuheda dam, first conceived as early as 1956, is soon to be constructed in the northern area of Maqarin, about 20 km north of Irbid, to store the waters of the Yarmouk River.

The estimated stream-flow at the Maqarin gauging station is 273 million m per year on average, which includes the flood waters that are discharged downstream without any use. On the basis of the riparian agreement between Syria and Jordan in 1988, preliminary work for an 800-m-long diversion tunnel was completed at the end of 1989. The reservoir is to have a gross capacity of 225 million m, with an effective storage volume of 195 million m annually. The water would irrigate an additional 3,500 ha in the Jordan valley and supply 50 million m of water a year to the Greater Amman area and the eastern heights. A power station near the dam would generate an average of 18,800 kWh of electricity a year. Syria will use part of the water and 75% of the total hydroelectric power generated. The project was stopped, however, by opposition from Israel, which wanted more water in the Yarmouk River downstream.

4.3.2 Groundwater resources

Groundwater has been exploited extensively in northern Jordan because the population was originally concentrated in this region. Groundwater has been used exclusively for M&I water supply, owing to its better quality and higher elevation than any of the surface water resources.

The Amman and Zarqa wellfields, which were developed to supply water for the municipalities of Amman and Zarqa, had the capacity to provide 16-17 million m per year in the 1950s to supply 50% of the demand. Azraq oasis, 100 km east of Amman, was developed to supply M&I water for Amman municipality. To meet the increasing demand for M&I use in the 1980s, both the Amman-Zarqa and Azraq wellfields were over-developed, lowering their piezometric heads, which caused deterioration in their quality.

Two important artesian wellfields, the Mukheiba and the Wadi Arab wells, were exploited in the mid-1980s in north-west Jordan. The Mukheiba wells, near the Adasiya intake site of the EGMC, are currently used for irrigation in the Jordan valley through an 11.5-km canal with a capacity of 3 m/sec. The sustained yield of the wellfield is estimated to be 20-25 million m per year, and its quality is suitable for drinking purposes. The Mukheiba wells represent the best available source for incremental supply of M&I water to the Jordan uplands. The Wadi Arab wellfield, located just upstream of the Wadi Arab dam and reservoir, has been developed to tap the aquifers in the Amman formation (B2) with an estimated safe yield of 10 million m per year. The highly confined groundwater in the Amman formation is believed to supply a group of springs in the wadi beds which were the source of base flow of the Wadi Arab; abstraction of the artesian water from the formation has substantially reduced the base flow of the Wadi Arab and the Wadi Arab reservoir. The Wadi Arab dam is now largely dependent on pumping from the EGMC for recharge and storage.

Two other wellfields, the Wadi Ajib (15 million m of safe yield per year) and the Wadi Dhuleil (20 million m of safe yield per year), situated to the north and north-east of Amman, have been exploited for the purpose of local upland irrigation and M&I use (World Bank 1988). The Wadi Ajib wellfield is being over-developed to abstract 14 million m per year for M&I water supply and 14 million m for irrigation, while the Wadi Dhuleil wellfield is developed exclusively for irrigation purposes. The quality of the aquifer below the irrigated land has suffered progressive deterioration from over-pumping and contamination by irrigation return flows.

The Disi aquifer (350 km south of Amman) is the most precious and extensive aquifer in Jordan. It is being exploited both for M&I use for Aqaba and for arid-land irrigation. Greatly enlarged areas of land have recently been developed for agriculture or are being planned for, which implies much higher extraction rates. As the aquifer is extremely expensive to develop for irrigation because of its depth, irrigated agriculture is unlikely to be economical. Furthermore, Disi as a typical fossil groundwater, source, which with the AlWuheda dam, represents Jordan's last substantial unexploited fresh water resource, should be regarded as a strategic water reserve.

Fig. 4.3A Water transport systems in Jordan-northern portion

Fig. 4.3B Water transport systems in Jordan-southern portion

4.3.3 Hydro-power

Owing to the scarcity of rainfall and water resources, the potential for hydropower generation is quite small. Since priority is given to irrigation and M&I purposes, most of the energy produced cannot be dependable. There are only two existing mini-hydro-power plants, which were completed in 1987: two 2 MW units installed at King Talal dam, and a 375 kW unit at Wadi Arab dam. For the Wadi Arab plant, the water is pumped from the EGMC for storage of surplus water (1.2 m/sec) and released back into the canal during times of deficit (1 m/ see). The annual potential energy generation of these two plants (12 million kWh) represents only 0.2% of the expected total power generation in Jordan in 1990. The only future hydro-power plant foreseen would be associated with the Al-Wuheda dam and have an installed capacity of 15 MW. The recent riparian treaty between Jordan and Syria envisages that 75% of the electricity produced would be consumed in Syria.

4.4 Non-conventional water-resources development

Jordan, being semi-arid to arid, has a mean annual rainfall of only 114 mm. The potentially exploitable renewable water resources are further limited to about 900 million m per year, which will be fully exploited by the year 2000 owing to increasing demand especially in the population centres. As has been noted, however, the hydrology and hydrogeology of Jordan provide a wide range of alternative water sources such as rivers and streams, springs, flash floods in the wadis, renewable and non-renewable groundwater, the return flow of treated sewage effluents, and seawater. The non-conventional water sources are primarily the reclamation of urban waste water, brackish groundwater, and seawater, of which the present status and the future development plans are described in this section.

4.4.1 Reclamation of urban sewage waters

The Water Authority of Jordan has an ambitious ongoing sewage treatment programme, which not only will have positive environmental and health impacts but will also provide for the collection and treatment of sewage in a way that effectively lends itself to the reuse of treated effluents. Sewage collected in north Jordan is expected to increase from 29 million m in 1985 to 116 million m by 2004 and 165 million m by 2015, most of which will be reused in downstream irrigation in the Jordan valley. Ongoing sewage projects include construction of new sewage treatment plants in Baqa and Wadi Sir and extension of the existing plants in Salt and Jerash. These plants have priority because their effluents are discharged upstream of the Zarqa basin and will be reused in downstream irrigation through regulation by the King Talal reservoir.

4.4.2 Brackish groundwater

Brackish groundwater is generally stored in deep aquifers except in the southwest, where the Disi formation or Precambrian complex outcrops. The quality of the brackish groundwater ranges from 1,0002,000 mg of TDS per litre to 5,000-10,000 mg/l, which is good for neither domestic use nor irrigation. Brackish groundwater with salinity of less than 2,000-3,000 mg/l, can be used directly for some crop irrigation, depending on pervious or sandy soil conditions. Another potential use for brackish groundwater is for specific purposes in the mining industry such as for washing water. In general, brackish groundwater can be safely used after desalination or mixing with very fresh water.

Brackish groundwater has been found in some places in the Jordan valley, and has been accidentally detected in some deep sandstone aquifers such as the Kurnub formation on the uplands during either exploratory or exploitation Grillings, but no systematic study or investigation of brackish-water potential has been undertaken. However, a large storage potential for brackish groundwater is conceivable in the rather shallow aquifers of the eastern desert of Jordan, including the areas of Azraq, Sirhan, and Hamad. In these areas, the target aquifers will be the Amman-Wadi Sir (B2/A7) formation, which is underlain by the shallow aquifer unit of Rijam (B4). These brackish aquifers may exist at depths of 200-300 m and 500-700 m with l DS of 2,000-5,000 mg/l. From the scanty piezometric data, the depth to the water table from ground level is expected to be only 100-200 m in wadi depressions including the Azraq and Sirhan. This brackish groundwater potential is situated only 100150 km east of Amman, which suggests a potential source of water supply for the Amman municipalities if cost effective desalination is performed. The most important cost factor in such desalination is the energy cost, which can be controlled by introducing off-peak power operation, taking into account the dominant steam-power generation with high peak demand in Jordan. Recent innovative research in the high-molecular membrane industry could provide the necessary energy saving through the use of low-pressure reverse-osmosis modules for brackish water demineralization.

A large amount of exploitable brackish groundwater is conceivably stored in the deep sandstone aquifers in southern Jordan, such as the Kurnub and Khreim formations. A case study on their nature and potential use for desalination and water supply is provided in the following section.

4.4.3 Seawater

Desalination of seawater for M&I water supply is the principal source of water in the oil-producing Gulf countries. Conventional distillation by the dominant multi-stage flash (MSF) method will be too expensive in Jordan, except for specific projects. Furthermore small-scale MSF desalination, for example to satisfy local water demand for the Aqaba municipal water supply, has a scale demerit to achieve the cost feasibility. Adding seawater desalination by reverse osmosis, however, may improve costs even for small- and medium-scale desalination plants. Thus the Aqaba steam-power station might be viable as a co-generation station either with MSF or RO. Hybrid desalination with MSF-RO and power will be a key element for regional water-resources planning in Aqaba district. Techno-political alternatives, including seawater pumped-storage hydro-powered RO desalination for co-generation, are described in section 5.6 in a case study on the inter-state Aqaba regional economic development plan for peace.

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