Development of Limited Water Resources: Historical and Technological Aspects October 2000

View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Hochschulschriftenserver - Universität Frankfurt am Main Development of Limited Water Resources: Historical and Technological Aspects October 2000 by Dr. Dov Sitton Applied Research Institutes, Ben-Gurion University of the Negev Historical background ". and the scorched land will become a pool, and the thirsty ground springs of water" (Isaiah 35:7) Scarcity of water has always been the dominant factor in agriculture throughout most of the arid Middle East, with its population relying on scanty and erratic seasonal rains or on rivers for their water supply. In Egypt, for example, the Nile was the only stable source of water in an otherwise desert landscape. In ancient times, sustained agriculture was limited to narrow strips of land on either side of the river. Even today, farming in Egypt is localized mainly along the banks of the Nile. The climate of present-day Israel is strongly affected by the proximity of the desert to the south and east. Most of Israel's territory is classed as arid (60%) or semi-arid. Rain falls only in the winter, mainly between November and March. Average annual rainfall ranges from 400 to 800 mm. in the northern and western parts of the country and declines sharply toward the south and east. A dry season with practically no rain prevails from about the beginning of April to the end of October. Until the beginning of the 20th century, agriculture in the Land was almost entirely rainfed, and therefore was limited to the northern part of the country and the coastal area. In some northern localities, where spring-water was available, fields were irrigated. The water was conveyed by gravitation from the source to the fields in open dirt canals. Each farmer was supposed to get his share of water for several hours once every few days or weeks. However, due to heavy loss of water along the transportation route - resulting from fast percolation into the ground - the water was distributed unevenly, and farmers furthest from the source were left with little water. Along the coast, underground water was raised from shallow wells with the help of 'norias' (bucket-type water-wheels) driven by donkey or ox. The water was collected in a pool and from there conveyed by gravitation to adjacent plantations (mainly orange groves). Such wells were dug manually and the output was low. The notion that agriculture requires a reliable water supply began to take hold only at the end of the 19th century and the beginning of the 20th century. This revolutionary change in attitude was introduced to the area mainly by the Jewish settlers, who were ready to adopt advanced technologies and know-how. Such technologies were introduced by immigrants with specialized skills and professional training. Among them were people experienced in advanced methods of drilling through hard layers of rock and pumping large quantities of water from deep wells. 1 The role of irrigation in advanced agriculture The use of irrigation in traditional farming is hampered by several constraints: Sources of water, especially under arid and semi-arid conditions, are usually very limited in quantity and are not readily available. Water is conveyed to the fields in canals by gravitation, which means that the ground needs to be leveled. Hilly terrain and slopes, therefore, cannot be irrigated by this method. The traditional practice of constructing dirt canals results in considerable loss of water due to percolation of water into the soil. The longer the canals, the larger the loss. The supply of water declines along the line of distribution, leading to unequal sharing of the limited resources. Another disadvantage of traditional irrigation is that the water supply is inevitably irregular, resulting in an inability to meet the needs of the crops and thus in poor yields. In view of the circumstances prevailing at the turn of the 20th century in the area, notably the predominance of dry farming with its almost exclusive reliance on seasonal rains, the introduction of new concepts into agriculture involved not merely technical changes but also profound modification of the strategy and scale of agricultural progress. Two main elements are responsible for the passage from traditional to modern water utilization in agriculture: the human factor, and the introduction and use of newly imported technologies. Following the establishment of the British Mandate at the end of the First World War, many Jewish immigrants came to Palestine, mainly from Europe. Many of their number were highly motivated and keen to establish new agricultural settlements. They were inclined to examine and apply new agrotechnologies, they understood the significance of modern know-how based on scientific studies, and they were eager to take advice from scientists and professionals. But perhaps the pivotal factor in their success was their ability to join together and establish organizations for the purpose of raising funds, formulating policies, and drawing up plans for physical development. All these efforts culminated in the 1920s and 1930s in the establishment of a large number of new agricultural settlements. As part of the settlement movement, geologists led by Prof. L. Picard (who immigrated from Germany in 1924) were recruited to search for underground water. Modern drilling equipment capable of drilling to great depths through hard rock layers, efficient pumping machines and newly introduced materials such as cement and metal pipes were all enlisted to help develop dependable systems of water supply. However, beyond these technical efforts, the challenge was met by radically modifying the concept of what an adequate water supply should be. As mentioned earlier, rainfall in Israel is limited to winter and declines from north to south and from west to east. Furthermore, total annual rainfall fluctuates considerably, drought years being frequent. Planning and building a reliable water 2 supply system must take these constraints into account; that is, it must assure bridging between seasons (winter and summer), regions (north and south), and years (with adequate and inadequate precipitation). Thus, in the early stages, settlements joined together on a local basis, invested money to search for underground water, and succeeded in providing a more or less uninterrupted water supply. Later on, a broader view of the problem of water supply was adopted. The first concerted effort to build a large-scale project was in 1935. The leaders of this project were Levi Eshkol, later Prime Minister of Israel, and Simcha Blass, an engineer who became prominent in the design and development of all the main water projects in the country. The project was designed and carried out between 1935 and 1938 by Mekorot, the newly established public water company. The water came from three wells drilled into the western flanks of the valley of Jezreel. The main features of the project were: Conveyance of water in metal pipes under high pressure, allowing uninterrupted supply over long distances. The high pressure made it possible to irrigate the fields with sprinklers, superseding traditional flood irrigation. Incorporation of two concrete tanks and two open reservoirs, instrumental in providing a constant water supply. The water was pumped into the reservoirs at night, when the cost of electricity was relatively low; thereafter the water was channeled into the irrigation system without interruption. The issue of water resources availability and the potential for further development of advanced systems to provide adequate supply was not merely an academic or technological question. It also had political implications. Indeed, national rights to the land lay at the heart of the conflict between the Jewish and the Arab communities. British government policy was to place restrictions on the purchase of land by Jews, establishment of new settlements and also on immigration to Palestine, based on the argument that physical conditions prohibited further growth of the existing population. One of the measures taken by the leadership of the Jewish community to counter British policy was to demonstrate that, with proper development, the land could sustain a much larger population. Hence, considerable effort was invested in conceiving and designing water projects. Water supply projects In the late 1930s it was accepted by the leading figures in the field that the following principles should guide future water projects: Planning Any system developed to provide water should bridge between areas where water is available and those where it is in short supply, as well as between the rainy and the dry seasons. Therefore, water from rivers, floods and springs should be stored in reservoirs, underground aquifers and tanks for eventual conveyance in supply lines 3 according to needs. Also, water surplus from rainy years should be stored for use in dry years. Water should be conveyed under pressure in pipes. While requiring substantial financial input, this approach circumvents topographic limitations and minimizes water losses, thus promoting long-term water saving. It also guarantees balanced and fair distribution among end users. Planning should be comprehensive. That is, the water projects must convey water all over the country to meet the needs of the growing population and of extensive agricultural development, especially in the Negev, the southern region of the country (the scarcity of rainfall characterizes the Negev region as arid land). From 1939 onwards, several plans for conveying water to the Negev were drawn up, mainly by Simcha Blass. A comprehensive study entitled, "Water resources in the Land of Israel: prospects for irrigation and hydro-electric development" was prepared by Mekorot in 1944, and at about the same time, experts on water and land conservation from the US became involved in studying and presenting schemes for water projects. W.K. Lowdermilk, a highly reputed American expert on soil conservation and hydrology, published a book ("Palestine - Land of the Promise") on the possibilities of developing water projects in Palestine, also in 1944.

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