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5.3 Water-resources development and management in Israel


The primary users of the waters of the Jordan River are Israel and Jordan. Between them, the Jordan River system has been extensively exploited; it satisfies about half of their combined water demand. The other riparian states are Lebanon and Syria; their use of the Jordan River at present is minor as compared to the others, and satisfies about 5% of their total demand for water.

The most comprehensive water-resources development and management in the Middle East to date is undoubtedly found in Israel. Following the establishment of the state in 1948, the government decided to undertake a comprehensive programme of water-resource development based on the ideas outlined by Lowdermilk (1944; cf. Appendix C). Two factors had considerable importance in the initial stages of development: the first was the lack of capital in the new state, and the second was the urgent necessity to provide water supplies for the many immigrants pouring into the country.

Up to about 1965 and completion of the National Water Carrier, there was enough water awaiting development to satisfy all needs. All that was required was new schemes to tap the resources and make efficient use of them. From the late 1960s onwards it became extremely difficult to make any extra water supplies available, and so emphasis had to be shifted to making more eflicient use of the available supplies.

In the late 1970s and early 1980s Israel had to face a growing demand for water from the urban and industrial sectors of its economy. It will now have to face the issue of diverting water from the agricultural sector, which still accounts for more than three-quarters of the country's total water use, to the municipal and industrial sectors of the economy.

5.3.1 Initial stage of water-resource development

Initially, attention was concentrated on low-cost projects, such as the drilling of wells, which produced quick results. These pumped wells permitted the irrigation of new lands on the coastal plain and in the northern Negev.

Efforts were made by Jewish rural settlers to improve the flow of the upper Jordan River in the Huleh valley during 1950-60. The Huleh valley, situated in the northernmost corner of Israel, was a marshy area where nobody could live before the 1950s. The marshy area was flooded by the winter flow of the upper Jordan River, and the stored water evaporated without productive use in the semi-tropical climate. Land-reclamation work was carried out by the immigrants to construct a series of canal and drainage systems to control both flood water and the groundwater levels in the depressions, to enable them to convert the valley from a useless marsh into fertile irrigation land.

Development of the upper river basin in conjunction with irrigation and drainage of the Huleh valley, however, both increased the saline nutrient flows into Lake Tiberias (the Sea of Galilee) and has resulted in a heightened concern over eutrophication. The chloride ion concentration in the lake rose from below 300 to nearly 400 mg/l between the years 1949/50 and 1963164, as shown in fig. 5.1. The increased utilization of water resources may not have been the only cause of this sharp increase in salinity, but it is conceivable that it played a major role in it.

5.3.2 Medium-term water-resource development

Medium-term development projects were chosen that permitted the maximum investment per unit of water supplied, were not technically complex, and allowed the investment to be divided into a number of stages. At the same time, the idea evolved that every project within the country, no matter what its size, should be able to be integrated into a nationwide hierarchical water-supply system. A number of long-term projects that had a regional rather than local significance were also implemented.

Fig. 5.1 Salinity change in Lake Tiberias (salinity conversion: TDS = 4 x Cl-), and increases in population and water use, 1949-1965 (Source: Buras 1967)

The Yarqan-Negev project, which was one of the early schemes of the National Water Carrier and was completed in 1955, carries water from Rosh Ha'ayin springs and groundwaters east of Tel Aviv in the Yarqon River basin southwards towards the Negev desert. The system provides 270 million m a year for Tel Aviv and for irrigating the Lachish area (Naff and Matson 1984).

The Western Galilee-Kishon project was the first large-scale conjunctiveuse scheme for developing both surface water and groundwater. It carries 85 million m a year from western Galilee to the fertile but dry Jezreel Plain (Naff and Matson 1984). The water source is mainly surface water during the winter months, when it is relatively abundant, and groundwater during the drier summer period.

The Beit She'an Valley project, about 15 km south by south-west of Lake Tiberias, exploits a perennial stream whose water is too salty for either drinking or irrigation purposes but can be utilized by diluting it with purer water from Lake Tiberias.

5.3.3 Integrated development stage: the Israel National Water System

The largest water-resource development project in Israel is the National Water Carrier, a huge aqueduct and pipeline network carrying the waters of the Jordan River southwards along the coastal plain region (fig. 5.2). This scheme stems from earlier ideas and concepts for the integrated development of all the waters of the Jordan for the mutual benefit of the states of Lebanon, Syria, Jordan, and Israel.

In the early 1950s discussions took place between Israel and the adjoining Arab states in an attempt to reach an understanding as to how the waters of the Jordan River might be most fairly allocated among the four states. This resulted in a plan drawn up for the United Nations usually referred to as the Main Plan: 1953. After prolonged negotiations, modifications to the original plan were made, and the new version became known as the Johnston Plan: 1955, named after the American mediator, Eric Johnston. The potential use of the Jordan's water was estimated to be 1,287 million m per year in total, of which 31% was allocated for Israel, 56% for Jordan, 10% for Syria, and 3% for Lebanon. It is widely assumed that the technical experts of the various countries involved agreed on the details of this plan, though soon afterwards the governments rejected it for political reasons. (See Appendix C for further discussion of these plans.)

With the failure of these negotiations, both Israel and Jordan decided to proceed with water projects situated entirely within the* own boundaries. As a result, Israel began work on the National Water Carrier in 1958. The main storage reservoir, and also the starting point of the scheme, is Lake Tiberias. From there water is pumped through pipes from 210 m below sea level to a height from which it flows by gravity to a reservoir at Tsalmon. After a further lift, the water flows via a canal to a large storage reservoir at Beit Netofa, which forms a key part of the system. South of Belt Netofa, the water is carried in a 270-cm diameter pipeline to the starting point of the Yarqon-Negev distribution system at Rosh Ha'ayin. In the initial stages 180 million m of water was carried per year. The capacity was increased to 360 million m per year in 1968, and it is believed that the maximum capacity now approaches 500 million m per year (Beaumont et al. 1988). This has, however, not yet been attained owing to the salinity problems of Lake Tiberias. At present, the national water grid interconnects all the major water demand and supply regions of the country with the exception of a number of desert regions in the south. In total, it supplies approximately 1.4 x 109 m per year, or about 90% of all Israel's water resources. More than half of the water is obtained from the Jordan and its tributaries, with a further 14% from the Yarqon River basin.

Fig. 5.2 Water-resources development plan for the Jordan River system

5.3.4 Conjunctive use and groundwater management

Many of the main groundwater aquifers in Israel are integrated operationally within the National Water Scheme. The pumpage from these aquifers has to be coordinated with releases of water from surface sources. The conjunctive operation of surface reservoirs and aquifers has been carried out in conjunction with artificial groundwater recharge schemes. Owing to the scarcity of suitable surface storage sites and the arid climate with high potential evaporation, part of the aquifer system, composed of Turonian-Cenomanian carbonate rocks, has been used as an underground reservoir to store the excess of winter stream flows through pumping wells and/or recharge wells (Schneider 1967; Buras 1967).

5.3.5 Water conservation

The total annual water supply was about 1.75 x 109 m in 1988, approximately 74% of which is used for irrigation, 19% for domestic use, and 7% for industrial use (fig. 5.3). Approximately 43% of the cultivated land, or 185,000 ha, is irrigated. Present estimates indicate that Israel currently uses as much as 95% or more of its total renewable water resources, including both surface water and groundwater (Beaumont et al. 1988).

There have been spectacular achievements in agriculture, and today almost all irrigation in Israel is carried out by sprinkler, drip, or sub surface systems. This has meant that a given irrigated area can now be watered with much less water than previously. At the same time it does mean, however, that little future water savings can be made by agriculture by increasing efficiency, as irrigation in Israel is as economical in water use as any in the world.

Fig. 5.3 Israeli water consumption by source and use (Source: CBSI 1992)

In the late 1970s and early 1980s Israel had to face a growing demand for water from the urban and industrial sectors of its economy. Experiments have been made to reuse urban waste waters through the Dan Waste-Water Recovery project, but success has been less than had been hoped for owing to difficulties in removing contaminants from the waste water. Research into various water desalination systems has concluded that distillation, such as the dominant multi-stage flash process used in the Middle East, is too expensive except for specific projects.

The result has been that Israel has been faced with the fact that the only way to obtain water for growing cities is to divert water from one use to another. This requires facing the issue of diverting water from the agricultural sector, which still accounts for more than three quarters of Israel's total water use, to the municipal and industrial sectors, taking into account the net effect on the economy of the state.

What seems likely to happen increasingly in Israel, as has happened in parts of the United States such as Arizona, is that irrigated land adjacent to urban centres will be taken out of cultivation and the water diverted to urban and industrial uses. By the early decades of the twenty-first century almost all the countries of the Middle East region will be facing similar severe water shortages in urban centres as their populations continue to grow. It seems inevitable, therefore, that water will have to be diverted away from irrigation to urban/industrial uses. Israel has been starting to reduce national water use since 1987 by cutting the supply of irrigation water, as seen in fig. 5.3. It was announced that allocations of water for agriculture in 1991 would be reduced by 30% from the 1990 level, and it seems that this was achieved.

5.3.6 Israel's occupation policy and water resources of the West Bank

The occupied lands, most notably the West Bank and Golan Heights, are important to the water economy and security of Israel. It is estimated that one-third of Israel's water resources originates in rainfall over the western slopes of the West Bank and is drawn from the same aquifer system that supplies the West Bank. Hence the Israeli occupation of the West Bank since 1967 has allowed greater exploitation of this aquifer by preventing new water-resource development by the Arab population. The effect has been to maximize groundwater recharge so that the aquifer under Israel can be more extensively developed. At the same time, Israeli settlements in the West Bank are also tapping the aquifer.

It should also be noted that another one-third of Israel's water comes from the Jordan River. The 1967 conquests are important in this light also because the Golan Heights afford control over the upper Jordan, enabling Israel to block any Arab attempt to divert its headwaters (fig. 5.2). Almost half of Israel's total water supply therefore consists of water that has been diverted or pre-empted from Arab sources located outside its pre-1967 boundaries (Naff and Matson 1984).


5.4 Joint Israel/Palestine/Jordan Mediterranean-Dead Sea conduit development with co-generation


A new co-generation method for Israel and Jordan is proposed here, which would produce both electricity and fresh water from the sea by means of a cogeneration system combining solar-hydro power generation and hydropowered RO desalination, based on exploitation of the 400 m elevation difference between the Mediterranean and the Dead Sea.

The co-generation system would produce 500 MW of electricity and 100 million m of fresh water per year from the Mediterranean Sea. The benefits would be shared by the riparians, including Gaza. It is assumed that the product of 100 million m of fresh water per year would be used exclusively to supply the central Ghor (the Jordan valley, in and around the Dead Sea), where the ground elevation is as low as 210-400 m below sea level.

The application of solar-hydro generation with RO desalination, which is a new type of co-generation system proposed here, is likely to be a key technological development in this region for the strategic objective of saving fossil energy and the global environment.

5.4.1 Background

This particular type of hydroelectric power development, also known as hydrosolar power, is made possible by the existence of a vast depression at a distance not too far from the sea, and the region's characteristically arid climate (with the resulting high degree of evaporation). Two such hydro-solar projects have been studied in depth: the Mediterranean-Qattara canal scheme in Egypt (discussed in section 2.11 above) and the Mediterranean-Dead Sea canal scheme in Israel (fig. 5.4). Both plans would involve an initial development stage during which the basins would be filled with water from the Mediterranean Sea up to a certain design level, which would be maintained thereafter by transfer of water to replace the amount evaporated.

Fig. 5.4 Locations of the Mediterranean-Qattara and Mediterranean-Dead Sea hydro-solar schemes

THE ISRAELI PLAN. Israel announced a feasibility study on a seawater hydroelectric power generation project in 1980, but this had been preceded by pre-feasibility studies over many years before that. The Mediterranean-Dead Sea Canal hydro-power project was designed to exploit the 400 m elevation difference between the Mediterranean Sea 0 m) and the Dead Sea ( - 402 m) by linking the two seas.

Various routes for the conduit to connect the seas were studied (fig. 5.5). The shortest, the central route, would be 72 km long, including a 15-km section of open canal and a 57-km tunnel 5 m in diameter. The first 30-km section would have crossed Israeli territory, and the second 42-km section would traverse the West Bank (occupied Palestine). This option was, however, put aside for fear of possible saline (seawater) water leakage through the tunnel which could contaminate fresh groundwater aquifers in the Judaea mountain range.

Fig. 5.5 Israel-Jordan Mediterranean-Dead Sea hydro-solar scheme project

After considering 27 alternative routes, the Gaza-Ein Bokok route with an 80-km tunnel length was selected in 1982 to minimize the capital cost. That route, however, would cross the occupied Gaza Strip. For political reasons, an alternative route was considered which would move the entrance of the canal northwards into Israeli territory; this would have added US$60 million to the cost and 20 km to the planned 100-km length (WPDC 1980). However, even if political problems in the Gaza Strip could be avoided, they would certainly have been encountered in Jordan, which shares the Dead Sea with Israel and also extracts minerals such as potassium from it. The planned effect of the canal would have been to raise the level of the Dead Sea by 17 m, from 402 to 385 m below sea level. This would have meant that the mineral processing plants in both countries would have had to be moved, and potash production could have fallen by 15% (WPDC 1980).

COST OF THE MDS PROJECT. The Israeli MDS solar-hydro development project with booster pumping would have generated 800 MW of electricity with annual generated electricity of 1.4-1.85 x 109 kWh, assuming a gross water head of 444-472 m and maximum discharge of 200 m/sec with an annual average flow intake of 1.23-1.67 x 109 m (Tahal 1982). The total project cost was estimated to be US$1.89 x 109 (at 1990 prices), assuming a 140% price escalation from 1982 to 1990, with the following major cost elements:

JORDAN'S COUNTER-PROPOSAL. Jordan vied with Israel over the canal power scheme in 1981 by proposing to bring seawater from the Gulf of Aqaba to the Dead Sea. This scheme would also have exploited the 400 m drop between the Gulf of Aqaba and the Dead Sea to generate electricity. Seawater would have been pumped into a series of canals and reservoirs from Aqaba to Gharandal, 85 km further north (fig. 5.5). From there, the water would fall into the Dead Sea to generate about 330 MW for eight hours a day at peak demand (WPDC 1983).

ENVIRONMENTAL PROBLEMS AND POLITICAL CONFLICT. The flow of water from the Jordanian carrier would have forced Israel to cut back its own influx of water into the Dead Sea, or the level would have risen so high as to flood the potash works (of both Israel and Jordan) and the surrounding hotels on the Israeli side. The Mediterranean-Dead Sea hydropower project was then put aside. Israeli interest then turned to seawater pumped-storage from the Dead Sea (WPDC 1989; Gaff and Matson 1984).

It should be noted that a United Nations mission found that the maximum level to have been reached by the Dead Sea would have been-390.5 m, which would not have flooded any religious or archaeological remains, nor would it have triggered earthquakes, as this level was comparable with previous equilibrium levels, and would not increase reflectivity. These studies therefore demonstrated that the project would not have had any adverse environmental effects (WPDC 1983). The possible increased evaporation through the introduction of Mediterranean water as discussed below could indeed have had additional beneficial effects.

DEAD SEA PUMPED-STORAGE SCHEME BY ISRAEL. Israel's Energy Ministry has recently shown renewed interest in a pumped-storage scheme on the Dead Sea, first proposed in the early 1980s but shelved in favor of a similar project proposed for the Sea of Galilee. Power could be produced even more cheaply and efficiently from pumped-storage on the Sea of Galilee in northern Israel, but the project could damage plant and animal life. The interest has therefore shifted back to the Dead Sea because of its almost total absence of flora and fauna. The Dead Sea pumped-storage scheme could produce 400-800 MW, equivalent to 7%-14% of the Israeli national grid's generation capacity of 5,835 MW in 1991. The total production of electricity amounted to 20.8 x 109 kWh in 1991.

CO-GENERATION WITH JOINT DEVELOPMENT: THE opportunity FOR THE FUTURE While Israel's MDS canal scheme was conceived to provide hydroelectric power, it did not offer any solution to the urgent need for fresh water supply (Glueckstern 1982). The use of hydroelectric power to make desalination cost-effective was a consideration of the scheme in the early 1980s, but it was not considered sustainable to use valuable clean energy from hydroelectricity for conventional desalination because the substantial energy losses that would be incurred through conversion and transmission. Discussion of the MDS canal scheme in the early 1980s overlooked the concept of shared resources and the benefit of joint development. Indeed up until 1991 there was no attempt to conceive a comprehensive development plan for the Jordan River system including linkage of the MDS canal and the Al-Wuheda dam on the Yarmouk (Murakami 1991).

The new co-generation approach to the MDS canal scheme proposed here takes into account (1) recent innovative developments in membrane technology for RO desalination which aim to save energy and to make RO desalination more cost-effective and (2) recent changes in the Middle East political situation following the Gulf war that may make comprehensive basin development not only technically and financially feasible but politically desirable and urgent.

5.4.2 Hydrology of the Dead Sea and evaporation from it

The climate of the watershed ranges from "hot arid" in the bottom of the Jordan valley to "Mediterranean semi-arid" in the surrounding highlands. The Dead Sea is a brine water body with the extremely high salinity of 250,000 mg of TDS per litre. It is a closed lake with no outlet except by evaporation, which at present amounts to 1,500-1,600 mm per year (Carder and Neal 1984).

Evaporation from the surface of the saline lake is the key factor in estimating the capacity for generating electricity by solar-hydro development. For the same meteorological inputs and aerodynamic resistance, a decrease in salt concentration will increase evaporation rates and reduce lake temperature, whereas an increase in concentration will have the reverse effect. Increased use of water from the Jordan River, especially for irrigation, has increased salt concentrations, whereas the proposed introduction of Mediterranean Sea water into the Dead Sea via a canal for hydroelectric purposes would reverse this trend (Weiner and Ben-Zvi 1982).

A model analysis to predict the annual evaporation rate and surface temperature as a function of aerodynamic resistance and thermodynamic activities of water (Carder and Neal 1984) assumed that on an annual longterm basis the heat flux into the lake was negligible and that the available energy could be equated to the net radiation calculated from the following parameters for the Dead Sea: air temperature (T) = 23.6C, vapour pressure of air (e) = 15.9 mbars, saturation vapour pressure of water at temperature T (es(T)) = 29.05 mbars, and total available energy (H) = net radiation flux density (Rn) = 146 W-m. The activity of the water in solution (aw; the aw of pure water = 1.00) was assumed to have changed from 0.75 before 1958 to 0.71 in the 1980s. If the proposed canal development were completed, the formation of an unmixed Mediterranean water surface layer (aw = 0.98) overlying the denser Dead Sea water would (possibly on a localized scale in the vicinity of the canal outlet) decrease the surface water salt concentration and raise the aw values. The model prediction suggests a large increase in the (local) mean annual evaporation rate by 345 mm, from a present 1,563 mm to 1,908 mm, and a marked decrease in surface water temperature of 3.3C, to 23.4C. These estimated rates of evaporation are conceived to be conservative and are comparable to those measured at Lake Mead in Arizona, in the United States, which amount to 2,000 mm per year (Sellers 1965).

This study assumes 1,600 mm of mean annual evaporation for present conditions. The evaporation rate after impounding water from the Mediterranean is assumed to be 1,900 mm per year for the cogeneration plan proposed in the following sections.

5.4.3 Co-generation plan: Solar-hydro and hydro-powered reverse osmosis desalination

The proposed solar-hydro development plan would exploit the elevation difference of 400 m between the Mediterranean Sea and Dead Sea. The water in the Dead Sea would be maintained at a steady-state level, with some seasonal fluctuations of about 2 m, between 402 and 390 m below mean sea level, with the inflow into the Dead Sea balancing evaporation.

The Israel/Jordan Mediterranean-Dead Sea conduit plan is a co-generation alternative that would combine solar-hydro and hydro-powered seawater RO desalination (fig. 5.6). It would have the following major components:

>> an upstream reservoir (the Mediterranean) at sea level (0 m), with an essentially unlimited amount of water,

>> a seawater carrier, in tunnel, canal, and pipeline, with a booster pump,

>> an upper reservoir and surge shaft at the outlet of the seawater carrier to allow for regulating the water flow,

>> a storage-type hydroelectric unit capable of reverse operation to allow the system to also work as a pumped-storage unit if required,

>> a downstream reservoir (the Dead Sea), at a present surface elevation of approximately 402 m below sea level,

>> a hydro-powered RO desalination plant, including a pre-treatment unit, a pressure-converter unit, the RO unit, an energy-recovery unit, a posttreatment unit, and regulating reservoirs for distribution.

Fig. 5.6 MDS hydro- solar conduit development alternatives

5.4.4 Estimate of hydro-power

The theoretical hydro-potential to exploit the head difference between the Mediterranean Sea (0 m) and Dead Sea ( - 400 m) by transferring 56.7 m of seawater per second (1.6 x 109 m per year) is estimated to be 194 MW, or, with an installed capacity for peak-power operation at 495 MW, to provide 1.3 x 109 kWh of electricity per year. Another option for exploiting the gross head at 444-472 m (Tahal 1982) by transferring 43 m of seawater per second would have 198 MW of theoretical hydro-potential, or, with an installed capacity for peak-power operation at 505 MW, to provide 1.33 x 109 kWh of electricity per year. These estimates are based on the following conventional equations for theoretical hydro-potential (Pth) and installed capacity (P), both in kW, and potential power generation (Wp) in kWh per year:

Pth = 9.8 x Ws x Q x He,
P= Pth X Ef,
Wp= 365 x 24 x Gf x P.

where

Ws = specific weight of seawater ( = 1.03),
Q = Flow discharge (m/sec),
He = effective difference head of water (m),
Ef = synthesized efficiency (=0.85),
Gf = generating efficiency (=0.30; 8 hours a day of peak operation).

5.4.5 Hydro-powered seawater reverse-osmosis desalination

The co-generation system is an application of seawater RO annexed to a solarhydro-power system requiring eight hours a day of peak operation. Marginal operation of the RO system is designed to use the hydropotential energy in the pipeline-tunnel (penstock) system (481.5 m of differential head of water) for 16 hours a day during the off-peak time. The feed-water requirements to produce 100 million m of permeate per year with 1,000 mg of TDS per litre are estimated to be 333 million m per year, assuming at least a 30% recovery ratio. The installed capacity is estimated to be 322,300 m per day, with a load factor of 85%. The energy recovery from the brine reject is estimated to be 24,000 KW, with annual generation of 134.7 million kWh of electricity, with a load factor of 68%. The recovered energy (electricity) will be used to supply electricity for the post-treatment process or other purposes, as shown in fig. 5.7.

COST ESTIMATES. The total investment cost for the proposed hydropowered seawater RO desalination unit, based on 1990 prices with 8% interest during three years' construction, is preliminarily estimated to be US$389,355,000, with an annual capital cost at US$18,568,000, with the following major elements:

The annual cost of operation and maintenance is estimated to be US$44,387,000, with the following major elements:

These cost estimates are based on 1990 prices and the following assumptions:

Fig. 5.7 Schematic diagram of a co-generation system for the MDS conduit scheme

Table 5.1 Water and electricity tariffs in six world metropolises

  Water Electricity
Yen/montha US$/m Yen/montha US$/kWh
Tokyo 4,070 1.23 4,962 0.18
New York 746 0.23 12,000 0.44
Los Angeles 4,800 1.45 3,600 0.13
London 2,860 0.87 3,913 0.14
Paris 2,513 0.76 4,700 0.17
Cairo 12,892 3.91 1,055 0.04

Source: LAJ 1989.

a. Japanese yen for 22 m of water and 180 kWh of electricity per month.

The unit water cost of the hydro-powered seawater reverse-osmosis desalination for the design annual product water of 100 million m is estimated to be US$0.68/m, which may be reasonable value when compared with international water tariffs, as shown in table 5.1.

The project cost of the Israeli MDS canal for the hydro-power scheme was estimated at US$1.9 x 109 as described in section 5.4.1 above.

5.4.6 Method of sharing and allotment

The Dead Sea surface, which is the source of evaporation for the MDS solar-hydro scheme, is the joint heritage of the riparian states: Israel (300 km, 30%) and Palestine and Jordan (700 km, 70%). The route of the MDS conduit would pass through Palestine (Gaze) (10 km) and Israel (90 km).

The water balance of the Dead Sea for the co-generation scheme to produce 500 MW of electricity and 100 million m of fresh water is estimated follows:

The riparians, Israel, Palestine, and Jordan, share the resources and must find a way of sharing the benefits. If the cost sharing were to be split fifty-fifty between the riparian states to assure fifty-fifty benefit allotment, project formulation including financing, construction, operation, and maintenance could be done by an international consortium sponsored by an international agency such as the Middle East Development Bank. The possible benefits and their allocation are discussed further in Appendix D.

5.4.7 Remarks

This study of hydro-solar development has been made to test the technical feasibility of exploiting seawater resources by taking into account the distinctive nature of the arid zone hydrology and topography in and around the Dead Sea. Reverse osmosis is the cheapest process for desalination today, but it may not be the optimum solution in the twenty-first century. Further research will be needed to evaluate its technical feasibility, including (1) the actual rate of evaporation from the Dead Sea surface after impounding, (2) the design of materials to avoid corrosion of hydraulic structures from seawater and brine reject water, (3) tunnel-boring-machine methods of construction for the seawater conduit tunnel, (4) application of low-pressuretype (3050 kg/cm) RO-membrane modules for seawater desalination, (5) an improved energy-recovery system in RO, (6) methods of hybrid desalination, and (7) the potential development of technology for power generation by a solar pond.


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