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5 Options for the Future: Balancing Water Demand and Water Resources
Pages 100-168

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From page 100...
... , lowering water levels and salinizing freshwater aquifers; similar examples of overexploitation are occurring throughout the study area. Attempting to meet future regional demands by simply increasing withdrawals of surface and ground water will result in further unsustainable development, with depletion of freshwater resources and widespread environmental degradation.
From page 101...
... Although some conservation measures are costly, most compare favorably with measures to increase water supplies. Moreover, water conservation measures invariably have a positive effect on water quality and the environment, if only by minimizing the impacts on freshwater resources and the volumes of wastewater generated by human activities.
From page 102...
... , the Israeli Water Commission has estimated that municipal water use in Israel could be reduced by 55 million m3/yr if voluntary conservation measures were widely implemented. Table 5.1 summarizes the household water savings that can be achieved using water-saving appliances.
From page 104...
... This development of new and larger water distribution facilities will increase the rate of water use unless restrictions are put in place first. As a further indication of potential water savings, municipal authorities in the West Bank report that water losses unaccounted for in the distribution network range from 26 percent in Ramallah to 55 percent in Hebron (Hebron Municipal Water Engineer, personal interview, 1996~.
From page 105...
... Minimizing these sources would result in increased flows to Wastewater treatment plants, which in turn would increase the amount of water available for reuse (see "Wastewater Reclamation" below)
From page 106...
... In conclusion, Table 5.3 shows that urban water conservation efforts are attractive when evaluated against the five criteria established by the committee. Although conservation will not usually result in augmentation of available supplies one possible exception being the repair of leaky distribution systems conservation measures are generally technically and economically feasible; have no adverse environmental consequences; and, by conserving current water supplies, tend to preserve the resources available for both present and future generations.
From page 107...
... The alternative for sustainability is to develop local water resources and use them prudently, and at the same time to capitalize on local conditions and local resources in producing marketable products for export. Capturing local runoff and flood water can increase water supplies for dryland extensive agriculture (Evenari et al., 1982)
From page 108...
... In the West Bank and Gaza Strip, 1996 agricultural water use was about 7,150 m3/yr per hectare, much of it in drip irrigation and greenhouse agriculture. In Israel, where drip irrigation is widely practiced, the 1995 average agricultural water use per hectare was 5,700 m3/yr, down from 8,600 m3/yr in 1955 (see Figure 5.1)
From page 109...
... This process occurred in Israel during the early years of crop irrigation and was partly responsible for reducing average per hectare water use over the past four decades, as illustrated in Figure 5.1. There is a limit to how much this approach can contribute to water savings, however, because water quality already limits the kinds of crops that can be profitably grown in the study area.
From page 110...
... The water available does not increase because the conserved water has already been reused and allocated elsewhere. The environmental impact of agricultural water conservation also varies, with adverse impacts occurring where existing irrigation tailwaters or return flows support some environmental purpose.
From page 111...
... OPTIONS FOR THE FUTURE 111 water conservation results in net savings of water, it will tend to preserve water resources now and for future generations. Industry Water use in the industrial and commercial sector accounts for a relatively small percentage of total water use in the study area, ranging from 3 percent in the West Bank to 6 percent in Israel (Table 2.3~.
From page 112...
... Government-imposed water-use restrictions and pricing policies, together with wastewater quality requirements and impact fees, should motivate industrial and commercial users to reduce their water use. In Jordan, the steel and paper industries are recycling their cooling water with significant water savings.
From page 113...
... In most regions of the world, strategies for developing and managing water resources have focused on the provision of water supplies. The emphasis on developing and augmenting water supplies generally leads to water pricing policies that emphasize achieving revenues sufficient to cover the costs of this development.
From page 114...
... As a general rule, the prescription for pricing water in water-scarce regions is to set the price of water equal to the marginal cost of supplying the last unit delivered (Hirshleifer et al., 1960; Russell and Shin, 1996~. As long as marginal costs are higher than average costs which is usually the case where water is quite scarce the use of marginal cost pricing will ensure that revenue requirements are met.
From page 115...
... Pricing policies that encourage conservation, including marginal cost pricing, time-of-use pricing, and water surcharges, generally work best where the quantity of water demanded is reasonably responsive to price. Thus, for example, where existing water supplies are insufficient or barely sufficient to serve basic drinking, cooking, and sanitation uses, an increase in water prices is unlikely to be effective in achieving water conservation.
From page 116...
... Although pricing practices do not augment available water supplies, they are technically feasible and, where they result in a net savings of water, tend to preserve water resources now and for future generations. The economic feasibility of pricing policies will vary from situation to situation, depending on price and income elasticities, which may vary throughout the region.
From page 117...
... , by developing sources of lower water quality (marginal quality water and desalinated brackish water and seawater) , by importing water from outside the study area, by transferring water within the study area (though imports and transfers are not analyzed in this report)
From page 118...
... Irrigation with water enriched in inorganic salts results in soil salinization and increased salinity of underlying aquifers and surface waters. Thus, irrigation, like many other uses of water, degrades water quality for later uses.
From page 119...
... In addition, it is almost always cheaper to prevent deterioration of water quality in the first place than to remediate the problem once deterioration has occurred. Maintaining water quality in effect augments available water supplies.
From page 120...
... This reservoir and some small ponds in the valley have created a severe drainage and salinity problem (Binyamin et al., 1991~. One option to increase the reliable water supply from the Yarmouk River is to construct the proposed Unity Dam.
From page 121...
... According to the Palestinian Water Authority, the quantity of stormwater runoff in the West Bank is 70 million m3/yr. Only 2 million m3/yr of stormwater runoff is generated within the Gaza Strip, although floodwaters originating in Israel make the total available runoff about 15 million m3/yr.
From page 122...
... Particularly in the wadis draining toward the Rift Valley, the recharged water would most likely create a storage zone of fresher water (compared to ambient water quality in the aquifer) , which could be withdrawn when needed.
From page 123...
... In most instances, watershed management will increase available water supplies. Situations in which management measures are undertaken to improve water quality may be an exception.
From page 124...
... The most common methods of water harvesting are the use of rooftop cisterns for individual domestic supplies, and catchment systems and storage ponds for agricultural supplies. Cisterns are used throughout the world for rural water supplies, and they are particularly common in villages within the West Bank (Anonymous, 1988~.
From page 125...
... Large-scale urban construction projects can incorporate systems to convey water from rooftop catchments to centralized treatment plants for inclusion in municipal water supplies. The use of ponds to store rainfall for livestock and irrigation is common in the Gaza Strip.
From page 126...
... Overexploitation of the coastal aquifer in Israel and the Gaza Strip, for example, has resulted in the landward encroachment of saline water. Because of the almost immediate environmental consequences of groundwater overdraft and the eventual environmental and water quality consequences of the total depletion of the resource, attempting to reduce extraction rates from overexploited aquifers should be a high priority in the study area.
From page 127...
... 127 ~ to o ~ CD · o En ~ MU ^, no o CD ~ no _ 5o ° ~ Vie ~ ~ 5, no V)
From page 128...
... What is known is that as water is withdrawn from aquifers containing fossil water, a continual decline in water levels occurs. This decline induces saline or brackish water from adjacent rocks to move into the aquifers to replace the freshwater removed from storage.
From page 129...
... Thus, ground-water overdraft can augment available water supplies in the short run but if overdraft persists, the quantities of water available decline. Ground-water overdraft is technically feasible, except where the depth to the water table is very great.
From page 130...
... . There are three categories of wastewater reclamation: (1)
From page 132...
... For agricultural applications, the quantity of directly reused water will be limited by water quality considerations, although blending or cycling drainage water with better quality water can increase its usefulness (Grattan and Rhoads, 1990~. Direct Use of Treated Wastewater Although it is technologically possible, treated wastewater is not used directly for potable supplies, because the public generally does not accept the concept (U.S.
From page 133...
... Urban nonpotable uses include landscape irrigation, toilet flushing, construction, vehicle and street cleaning, fire protection, and air conditioning (Okun, 1994~. Urban reuse of wastewater requires dual municipal distribution systems one for potable water and the other for reclaimed wastewater.
From page 134...
... Substituting reclaimed for potable water in irrigation obviously allows the more beneficial and efficient use of the limited freshwater sources. Forage and other crops that are not consumed by humans have the lowest water quality requirements, and for irrigation of these crops, effluent given only primary treatment is sometimes used.
From page 135...
... Industrial uses of water include cooling, boiler-feed, and process water. All three of these uses can take advantage of reclaimed wastewater, although additional treatment, ranging from pH adjustment to carbon-adsorption filtration, may be required.
From page 136...
... Where sufficient treatment is provided, environmental uses of reclaimed wastewater may provide an alternative method of storing reclaimed water. Commercial fish production in artificial impoundments of reclaimed water is widely practiced in Israel (Crook, 1990~.
From page 137...
... It suggests that wastewater reclamation may be a relatively attractive option for the study area. Like recycling, wastewater reclamation can significantly add to the region's available water supply.
From page 138...
... only within the region but in many other places throughout the world. Its environmental impacts are generally positive because it improves water quality in addition to stretching water supplies through reuse.
From page 139...
... Management practices for using brackish water in agriculture include restricting the use of brackish water to tolerant crops and tolerant varieties, although the latter are not widely available; mixing water sources, when required, to achieve lower salinity; intermittent leaching; use of drip-irrigation technology when practicable; use of poor quality water only toward the end of the growing season; and avoiding irrigation during hot weather (Shalhevet, 1994~. Although the use of brackish water for irrigation can free up freshwater resources for other uses, this practice is not without drawbacks even with sound management practices.
From page 140...
... , about 40 million m3/yr are available in the Gaza Strip, and an additional 200 million m3/yr of brackish water is available throughout Israel. With time, the quantity of marginal water in the area will increase because of saline water encroachment and the infiltration of pesticides,
From page 141...
... Eventually, the problem of water supply from the coastal aquifer will be one of quality rather than quantity. The long-term use of this aquifer and others with deteriorating quality will depend on finding suitable uses for marginal quality water.
From page 142...
... ) on nonbrackish water up to 2,000 mg/1 of total dissolved solids (TDS)
From page 143...
... Finally, the use of these waters will tend to promote sustainability, stretching existing water supplies further, thus preserving the stocks and qualities of water available now and for future generations. Desalination of Brackish Water According to the International Desalination Association (1996)
From page 144...
... ity of water are less expensive, they will doubtless be developed to their fullest extent before desalination plays a major role in the area's water supply. According to Fisher et al.
From page 145...
... This approach might answer the public reluctance to accept reclaimed wastewater as a potable supply, and it may be practical if the
From page 146...
... If salinity increases, the cost of desalination will generally increase; if salinity decreases, part of the adjacent freshwater resource will be depleted. Therefore, brackish water resources cannot be considered a "free good" or unlimited resource, but must be evaluated to determine their yield, salinity changes with time, and the effect of withdrawal on adjacent freshwater resources.
From page 147...
... Two technologies, electrodialysis and reverse osmosis, provide less costly means of desalting brackish waters. Electrodialysis.
From page 148...
... The costs of facilities using relatively modern reverse osmosis technologies range from about $0.28 to $1.00 per cubic meter. The costs for desalting brackish water with reverse osmosis compare favorably with electrodialysis and with wastewater reclamation where reclamation requires extensive treatment.
From page 149...
... Economic feasibility will depend on the quality of the feedwaters, the technology used, and the relative economic attractiveness of other alternatives. By stretching the existing water supply and providing qualitative improvements, brackish water desalination is likely to produce relatively favorable consequences for present and future generations.
From page 152...
... seawater desalination with costs that are relatively attractive compared to distillation technologies. Table 5.14 shows cost and capacity data for a selected set of seawater conversion projects employing reverse osmosis technologies around the world.
From page 153...
... aModified from National Water Supply Improvement Association, 1992. bModified from Leitner, 1991.
From page 154...
... The evaluation of seawater desalination is summarized in Table 5.11. Clearly, large-scale seawater desalination could substantially add to the available water supplies of the study area.
From page 155...
... While cloud seeding has been used in the study area since 1960, its effects on precipitation are still controversial. Moreover, increases in precipitation do not necessarily result in more runoff, which is critical to water supply.
From page 156...
... Further research is still needed to clarify the effects of cloud seeding on precipitation. At this time, it is doubtful that cloud seeding will ever provide a significant source of increased water supply in the study area.
From page 157...
... The implications of cloud seeding for present and future generations are similarly unclear. Transfers Within the Study Area Water transfers are used to shift water surpluses generated in one part of the system to another part in need of additional water supplies.
From page 158...
... CONCLUSIONS The conventional freshwater sources currently available in the region are barely sufficient to maintain its quality of life and economy. For example, Jordan is currently overexploiting its ground-water resources by about 300 million m3/yr, thus lowering water levels and creating salinization of freshwater aquifers.
From page 159...
... Agriculture Through rationing, research, and possibly economic pricing policies, agricultural water use can become more efficient. However, as regional nonagricultural water demand increases and the cost of additional water supplies grows more expensive, the role of agriculture in the area's economy will have to be reevaluated, so that as much water as possible is conserved.
From page 160...
... Conversely, pricing policies that promote economic efficiency and economizing in water use are more appropriate for regions of increasing water scarcity. Marginal Cost Pricing The committee recommends the use of marginal cost pricing in the study area to help conserve freshwater resources.
From page 161...
... Such simulation can also help identify additional water supply and conveyance facilities that are economically justified. Watershed Management The concept of total watershed management should be adopted for the study area.
From page 162...
... Brackish Water Desalination Where brackish waters can be desalted, this approach offers a clear promise of augmenting the available water supply. Such desalination is technologically feasible and will not usually have adverse environmental impacts.
From page 163...
... The prospect of major urban expansion in the area provides the incentive to plan communities with an initial dual-water system. Marginal Quality Water Use Some savings in freshwater could be obtained by substituting water of marginal quality for some activities now using potable water.
From page 164...
... 1994. Replenishment of Waters by Artificial Recharge As a Non-Controversial Option in Water Resources Management in the West Bank and Gaza Strip.
From page 165...
... 1995. Nitrate Removal and Water Quality: Improvements with Reverse Osmosis for Brighton, Colorado.
From page 166...
... 1990. Saline Water Processing: Desalinization and Functions of Sewater, Brackish water, and Irrigation Wastewater.
From page 167...
... 1991. Wastewater reclamation and water resources management.
From page 168...
... 1989. Variations in Rainwater Quality from Roof Catchments.


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