From there the line will extend west to Sirte. The constant increase in the price of the total scheme will have to be taken into account when figures are worked out for the cost of growing the wheat to be irrigated. The whole idea of using this valuable resource for agriculture is very much open to question, in which the groundwater irrigation accumulates substantial salts in the irrigated land.
The area west of the Nile is an arid plateau some m high, crossed by belts of sand dunes in the centre and west. The Nile is Egypt's most important feature. Rainfall is minimal: Cairo receives only 60 mm annually, while the desert often has no rain at all. A narrow stretch of the Mediterranean coast is milder and wetter, with mm of rain a year. Hydro-meteorologically Egypt is a desert, however, in which the surface hydrology of the Nile River is of direct practical importance.
The Nile is the basic source of water and, with the aid of dams and barrages, supplies an extensive network of distributary canals.
West of the Nile, Nubian sandstones that store a huge amount of fossil to semifossil water underlie the desert. Groundwater development in the depressions, where the saturated Nubian sandstone aquifer underlies, is the worthy complement of the green revolution in western Egypt. Abstraction of groundwater from shallow wells amounted to Seven deep boreholes drilled between and , with depths varying between The yield of these deep wells was Extensive deep production wells were drilled in the mids, to correspond with the New Valley project which aims to expand the cultivated area in the Kharga and Dakhla oases.
At first, much of the water was self flowing under artesian conditions. The pressure quickly fell, however, and an increasing use of water required ever greater amounts of pumping. Saline water began to contaminate some wells, limiting the crops which could be grown. The response of the head of water to the growing abstractions from the deep production wells in Kharga and Dakhla oases from to is shown in fig.
The Egyptian authorities are planning to augment extraction until it reaches 2. Extraction of the target volume will lead to a further decline in the piezometric head to cease the artesian flow.
Another problem of the development project is the human problem that many of the managerial staff do not like living in such isolated areas. Overall, the project cannot be considered a success Beaumont et al. Groundwater in the Damman aquifer on Bahrain island has been seriously contaminated by seawater intrusion or upward leakage from the underlying saline aquifer of Umm er-Radhuma since the s, owing to intensive pumping which exceeded the safe yield. The world's largest reverse-osmosis RO plant for the treatment of saline groundwater, which is located at Ras Abu-Jarjur, 25 km south of Manama, the capital of Bahrain, was commissioned in The RO plant was designed to meet the domestic water demand of Manama city, taking into account its several advantages over a seawater distillation MSF plant: 1 short construction time, 2 lower energy cost, and 3 ease of operation and maintenance Akkad The use of reverseosmosis desalination for saline groundwater in Bahrain island began in The data from its monitoring, examined here, provide one of the key sources of experience in the development of marginal water resources in the Middle East.
The population was estimated at ,, with a growth rate of 4. The climate is arid to extremely arid. Owing to the surrounding Arabian Gulf, the humidity is generally high. Rainfall is confined to the period between November and April, with an annual average of 76 mm, which occurs essentially in a form of ephemeral thunder showers.
There are no rivers, streams, or lakes. The country is occupied by Tertiary sediments, which are rather gently folded on a regional scale into elongate domes or periclines of near north-south trend. Bahrain island is dominated by one such dome, developed principally in carbonate sediments of Cretaceous-Tertiary age, which dip gently outwards.
The Bahrain dome is elongate about 30 km x 30 km and with slight asymmetry, as seen in fig. The sequence is composed of three formations: Damman, Rus, and Umm er-Radhuma, as seen in the schematic geological profile in fig. The Damman formation, which consists of fossiliferous dolomitized limestone, dolomitic marl, and dolomitic limestone, has two forms, known as Alat limestone and Khobar dolomite, from the Middle Eocene.
The Rus formation of the Lower Eocene consists of chalky dolomitic limestone, shale, gypsum, and anhydrite. The Umm er-Radhuma formation of the Palaeocene is composed of dolomitic limestone and calcarenite with some argillaceous and bituminous facies, which is underlain by shales, marls, and argillaceous limestone of the upper Arma formation of the Cretaceous.
The geological sequence and aquifer characteristics are shown in fig. Historically, Bahrain has utilized groundwater for both agriculture and municipal requirements.
Natural fresh-water springs used to flow freely in the northern part of Bahrain, but, with increased demand, spring flow has decreased and pumped boreholes became the normal means of obtaining water. With increased water demand after the exploration of offshore reservoirs of crude oil and gas in , spring flow decreased and pumped boreholes became the normal means of procuring water.
During the s, most of the springs ceased flowing, and further increase in water demand has caused deterioration in water quality, including the intrusion of seawater into the aquifer system. The principal aquifers are pervious limestone units in Palaeocene to Eocene sedimentary rocks. Damman and Umm er-Radhuma are the important aquifers in Bahrain. The Alat limestone in the upper Damman formation used to sustain small artesian flows or springs in the northern island. The Khobar dolomite in the lower Damman formation, a highly pervious unit, was the main productive aquifer to produce fresh groundwater, with a typical salinity of 2, mg of TDS per litre.
Due to excessive abstraction, however, piezometric levels in the Khobar aquifer declined continuously with substantial increase in water salinity figs. This aquifer has become saline in the Ali-Buri area, due to upward leakage of brackish water, and on Sitra, due to seawater intrusion fig. Significant upward leakage of brackish water from the underlying aquifer of Umm er-Radhuma occurs only in eastern and central Bahrain, where the evaporite layers in the Rus formation have been removed by solution.
The deeper aquifer of Umm er-Radhuma, composed of dolomitic limestone and calcarenite, is a salinity stratified aquifer with a total thickness of about m. A further highly saline groundwater contains hydrogen sulphide and hydrocarbons from bitumens as specific contaminants. Since it has become the policy to curb the abstraction of groundwater resources in the Damman aquifer and to improve its quality, such as the salinity of domestic water supply, further development of water resources will undoubtedly be by means of desalination, either by a thermal process or reverse osmosis.
The choice will depend on the sitespecific conditions and economy or cost. The first multi-stage flash MSF distillation plant was introduced in Bahrain in The raw water source is a highly saline groundwater 13, mg of TDS per litre in the Umm er-Radhuma formation, containing hydrogen sulphide and hydrocarbons from oil as specific contaminants.
The design TDS for the plant is 19, mall; it is predicted that this concentration will be reached after 10 years' operation. The predicted range in feed-water salinity is shown in fig. The plant contains five basic systems: a well-water supply, pre-treatment, RO desalination, post-treatment, and product-water transfer systems, as shown in the process flow diagram in fig.
Raw water is pumped from 15 boreholes, which include 13 duty wells and 2 standby wells. Four anti-surge tanks at the high and low points of the wellfield are installed to protect the collection pipes from sudden pressure surges.
The anti-surge tanks are pressurized with nitrogen gas to prevent oxidation of hydrogen sulphide in the well water. TO protect the RO system, well water entering the plant is filtered and chemically treated to remove silt, oil, and other hydrocarbons. The raw water passes through a series of dual media filters and carbon filters.
Sodium hexametaphosphate and sulphuric acid are then injected downstream of the carbon filters to prevent scaling of the system. Before entering the heart of the RO system, the water passes through eight micro-guard filters micrometre with polypropylene cartridge elements.
Seven horizontal multi-stage diffusertype high-pressure pumps are installed to feed water with an average pressure of 60 bar maximum pressure 69 bar. Each pump is equipped with Pelton wheel impulse-type energyrecovery turbines. The RO membrane unit comprises a total of 2, permeators.
The permeators are hollow fibre-type, such as DuPont B Since the well water contains a high level of hydrogen sulphide, the RO product water must pass through a series of stripping towers to remove the gas. Adjustment of the pH of the permeate with sulphuric acid is also needed before stripping for maximum removal of the hydrogen sulphide.
In-line mixers are installed in the pipeline for post-treatment with chlorine, lime, and carbon dioxide. As stated earlier, officials of the Bahrain Water Supply Directorate chose reverse osmosis desalination over multi-stage flash distillation because of the short construction time, lower energy cost, and ease of operation and maintenance.
The parameter that most readily demonstrates the performance of the system is the energy consumption per unit of product. The specific electric power consumption per product water is estimated to be as low as 5. Confines Dammam aquifers. Freshwater plays a pivotal role for sustainable development in the Mediterranean region. Water in the region is unequally distributed both in time and space.
Groundwater is a limited resource in the Mediterranean region, due to arid and semi-arid climatic conditions in many countries and to periods of periodic drought in others. Under these circumstances, aquifer recharge is significantly reduced. The reserves of groundwater and the storage capacity of aquifers play an economic and strategic role in guaranteeing agricultural production and urban water supply of the Mediterranean. The MENA region has among the lowest per capita amount of water supply in the world.
Issues of surface water have been at the forefront in much of the debate on water scarcities, water sharing and improved water resources management. Groundwater continues to be a hidden or forgotten issue that deserves much more attention among policymakers. Most countries in the MENA region are experiencing water scarcity combined with low water use efficiency in irrigated agriculture.
According to FAO, water use efficiency is about 40 percent. This is higher than in Latin America but lower than in South Asia. Out of countries ranked in the WWDR with regard to the annual per capita total renewable water resources availability, more than half of the countries in the MENA region are ranked in the lowest 10 percent.
This has caused almost all renewable water resources to be in use, and many countries have resorted to the use of their non-renewable water resources for agricultural, industrial and domestic purposes. Groundwater is a hidden problem, since many countries extract more than is being recharged. Weak enforcement of environmental legislation leads to groundwater pollution, which further decreases groundwater quality throughout the region.
In some cases, legislation is not comprehensive enough, lacking specific rules on solid wastes, hazardous chemicals, etc. A disproportionately large share of available freshwater is used in irrigated agriculture, but it is accompanied by an intensive use of fertilisers which also contributes to the water quality degradation through pollution and salinisation. The Jordan River, for example, is in poor shape due to overuse of the upper Jordan by Israel and overuse of its tributary, the Yarmouk River, by Syria and Jordan.
There is a great need for improved water resources governance, as well as improved water efficiency and productivity in irrigated agriculture. Population growth together with urbanisation and economic development further increases water demand, with serious implications for development and poverty reduction. Even though some countries in the region are on track to reach the Millennium Development Goal targets on improved water supply and sanitation, ongoing urbanisation will necessitate increased investments in water supply and sanitation.
According to the World Bank, the MENA region will have grown to a projected million in from around million in and the present million, bringing the per capita water average to extremely worrying levels. This raises ever bigger questions on the present approximately 80 to 85 percent of water that is used for irrigated agriculture in the MENA region.
The complexities of managing and sharing common water resources are well-known to the region. Conflicts over water in both intra-national and international settings evolve in complex political and hydrological environments. The water-intensive agricultural irrigation policies are motivated by the pursuit of national water and food security in countries with burgeoning populations but little economic diversification.
Some of the highest demographic concentrations in the world are found in the region, such as in the Gaza Strip. The water resources are used in an agricultural sector which produces little wealth in the MENA region economies.
It has been suggested that a gradual reallocation of water from irrigated agriculture to other economic uses that can provide a higher economic return industrial and services will be a more realistic and long-term sustainable policy option. Such change will not come easy since many people, the poor in particular, have agriculture as their economic mainstay and employment opportunity.
Many countries in the region are currently in a stage of institutional reform, orienting priorities and practices towards integrated approaches to water resources management. Also at the national level there have been some improvements in groundwater management.
For example, in Lebanon, Jordan and Syria water is under the public realm and the pumping and use of groundwater is regulated by legislation. Well drilling is subject to a permit, which also specifies the volume of water that can be extracted and its use. However the actual implementation and monitoring of legislation and permits continues to be a challenge for all three countries. In Syria, despite existing rules and regulations on required permits, almost 50 percent of the total number of wells in the country are considered illegal.
As previously noted, as much as 80 to 85 percent of the water resources in many MENA countries are used for irrigation and countries like Jordan, Lebanon and Syria rely heavily on groundwater.
For example, in Syria 60 percent of all irrigated areas are currently irrigated by groundwater. Despite existing rules and regulations on required permits, almost 50 percent of the total number of wells in the country are considered illegal. The consequences include water over-abstraction.
Too many times extraction exceeds groundwater recharge, leading to falling groundwater tables. In coastal areas over-used groundwater aquifers are suffering from salt-water intrusion.
Countries like Libya, Tunisia and Algeria are sharing vast amounts of groundwater. There are some exceptions to this, such as the groundwater between Palestine and Israel. Interesting cases are now emerging where countries have started to cooperate on transboundary groundwater, such as between Tunisia, Algeria and Libya regarding the North Western Sahara Aquifer System.
Cooperation has so far been on a technical level, such as jointly defining the boundaries of the aquifer, identifying areas where the pressure on the groundwater resource is the strongest and developing a common database.
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