Cover Image

PAPERBACK
$60.25



View/Hide Left Panel

Status of Agricultural Water Use in Iran

Amin Alizadeh and Abbas Keshavarz

INTRODUCTION

Because water is a critical natural resource, it has always played a vital role in progress and development. Since the first known human empire was established thousands of years ago in the southwestern part of Iran, water has played a key role in any social changes that have taken place in this country. For many people viewing Iran from outside of the country, water scarcity in this country may not appear to be as serious as in other countries of the Middle East. Nevertheless, with a population of more than 65 million people, Iran is actually one of the driest countries of the world. Even if all the renewable water resources could be utilized, excluding the incoming international river, the total amount is not more than 117 billion cubic meters (bcm). Considering that about 88 bcm are currently used each year, the country is left with about 30 bcm of additional water capacity for future use.

Today, the consequence of rapid population increase and the immigration of millions of Afghans is increased pressure for rapid water and land development. In addition, the processes of urbanization and industrialization and the development of irrigated agriculture to support population growth have raised the demand for water, but at the same time have reduced the supply.

Iran is an oil rich country, but water, unlike petroleum, has no substitutes and cannot be purchased in a world market that has many alternative suppliers. If the problem of water scarcity, not only in Iran, but also in other countries of the Middle East, is not solved, its most obvious consequence will be that millions of the people of these countries will seek refuge in other nations. Therefore, water scarcity is not an isolated national problem, but rather is a common problem of



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 94
Water Conservation, Reuse, and Recycling: Proceedings of an Iranian-American Workshop Status of Agricultural Water Use in Iran Amin Alizadeh and Abbas Keshavarz INTRODUCTION Because water is a critical natural resource, it has always played a vital role in progress and development. Since the first known human empire was established thousands of years ago in the southwestern part of Iran, water has played a key role in any social changes that have taken place in this country. For many people viewing Iran from outside of the country, water scarcity in this country may not appear to be as serious as in other countries of the Middle East. Nevertheless, with a population of more than 65 million people, Iran is actually one of the driest countries of the world. Even if all the renewable water resources could be utilized, excluding the incoming international river, the total amount is not more than 117 billion cubic meters (bcm). Considering that about 88 bcm are currently used each year, the country is left with about 30 bcm of additional water capacity for future use. Today, the consequence of rapid population increase and the immigration of millions of Afghans is increased pressure for rapid water and land development. In addition, the processes of urbanization and industrialization and the development of irrigated agriculture to support population growth have raised the demand for water, but at the same time have reduced the supply. Iran is an oil rich country, but water, unlike petroleum, has no substitutes and cannot be purchased in a world market that has many alternative suppliers. If the problem of water scarcity, not only in Iran, but also in other countries of the Middle East, is not solved, its most obvious consequence will be that millions of the people of these countries will seek refuge in other nations. Therefore, water scarcity is not an isolated national problem, but rather is a common problem of

OCR for page 94
Water Conservation, Reuse, and Recycling: Proceedings of an Iranian-American Workshop all the countries of the Middle East. In order to master the complex problem of water scarcity there will need to be regional cooperation and assistance. GEOGRAPHICAL LOCATION AND POPULATION Iran, with an area of 165 million hectares (Mha), is located in a semiarid region of the Middle East. Distribution of precipitation is uneven. The average amount of precipitation over the country is 252 mm/year, which is less than one-third of the world average. While annual precipitation usually exceeds 2,000 mm in some of the northern parts of the country, it may be less than 20 mm in desert areas. Although water surpluses exist in the mountain regions, the areas of high population concentration and high water demand are hundreds of miles away. Population growth in Iran is high. The highest recorded rate of 3.9 percent occurred in 1986. But a remarkable achievement of Iran in applying family planning programs during the years of 1986-1996 contributed to a lower rate of population growth of 1.45 percent in that decade (Ghazi, 2002). The latest census figures showed the population of Iran to be 60 million in 1996. Today, it is estimated that the population of the country may be more than 65 million. It is also expected that the population may double by 2021 (Plan and Budget Organization, 1999). Rapid population growth in the last two decades has changed the relative composition of the rural and urban populations. While the ratio of rural to urban population was 40/60 before the revolution, it is now reversed. By 2010 some 80 percent of the total population may live in urban areas and especially in big cities like Tehran, Mashhad, and Isfahan. Most of the water resources that sometime ago were used for agriculture are now used to supply drinking water to these cities. Altogether, population growth, urban and industrial growth, and agricultural development in Iran have created a condition of water stress. This situation is beyond a water shortage or crisis and aggregates the serious scientific, technical, ecological, economic, and social issues surrounding water for now and the years to come (Ghazi, 2002). WATER RESOURCES AND HYDROLOGY Available data for Iran’s freshwater resources are presented in Table 1. As is seen in this table, the average renewable water in Iran is 130 billion cubic meters only. However, since the hydrologists have been involved in measuring rainfall and river flow at catchment scales, these data may not give a complete and accurate image of water availability unless data are also measured at other scales. The level of water stress depends upon technical scarcity, demographic scarcity, and hydraulic density of population (Falkenmark, 1999). Given the high population increase and recent persistent drought conditions, Iran’s average annual supply of renewable freshwater per person fell from 2,254 m3 in 1988 to 1,950 in 1994, and the estimated figures for the years 2005 and 2020 are 1,750

OCR for page 94
Water Conservation, Reuse, and Recycling: Proceedings of an Iranian-American Workshop TABLE 1 Water Availability and Use in Iran Component Volume (bcm) Percent of Total Precipitation 413 100 Evaporation 283 70 Renewable water 130 30 Surface water 105   Groundwater 25   Total water use 87.5 100 Agriculture 82.0 94.25 Domestic 4.7 4.75 Industry (etc.) 0.8 1 and 1,300 m3, respectively (Ghazi, 2002). Biswas (1998) believes that generally a country will experience periodic water stress when freshwater supplies fall below 1,700 m3 per person per year. Given this statement, Iran is beginning to encounter water stress. Based on the data in Table 1, almost 70 percent of all annual freshwater resources in Iran are already under use, and the remaining 30 percent may not be technically feasible to use. As far as hydraulic density of population is concerned, spatial distribution of water resources in Iran is uneven. Almost 30 percent of all annual freshwater of Iran is concentrated at the southwestern part of the country, where only a very small percent of the population is located. According to these figures, and based on available freshwater resources, the population of Iran has reached its maximum capacity unless sustainable policies are focused on demand management. IRRIGATED AGRICULTURE According to the figures in Table 1, more than 94 percent of the total annual water consumption in Iran is used for agriculture, whereas the percentages for domestic and industrial uses are 4.75 and 1 percent, respectively. Even though most of the renewable water is used in agriculture, the productivity of water (ratio of yield per unit of water) is very low. Out of all water used in agriculture, 50 to 60 million tons of food material are produced. Therefore, the economic value per cubic meter is 0.75 kg/m3. The economic value of agricultural products in Iran (including rain-fed agriculture) is estimated to be U.S. $4.75 billion, which is about 26 percent of the gross domestic product (GDP). Despite the fact that only 10 percent of the total area of the country is arable, the area under irrigation is not more than 30 percent of the total cultivated land. Over the last decades, many attempts have been made to increase the area under irrigation by supplying water through construction of dams, but these attempts were not significantly effective. The amount of water regulated by dams in Iran is estimated

OCR for page 94
Water Conservation, Reuse, and Recycling: Proceedings of an Iranian-American Workshop to be 25 billion m3, which is 28 percent of the surface water used in agriculture (Plan and Budget Organization, 1999). As has been reported, no increase in irrigated land has been seen during the last four decades, except some development during the period of 1980-1990 (Ghazi, 2002). Although more groundwater was exploited and seven large dams were constructed during the years 1990 to 2000, the irrigated land area did not increase. While in 1999 Iran was the ninth highest wheat importer and the third highest rice importer in the world, in the year 2001, due to a prolonged drought, Iran rose to the position of fifth-highest wheat importer in the world. It should be remembered that in spite of heavy storage of oil, Iran is still an agricultural country, and the agricultural sector plays a very important role in the national economy. Almost 27 percent of the gross national product (GNP) and 23 percent of labor forces belong to agriculture (Plan and Budget Organization, 1999). It is predicted that a decade from now (around 2012), in order to feed the population of the country more than 100 million tons of food will be needed. By that time, water demand will increase to 126 bcm, and by the year 2021 it will exceed 150 bcm; this is 15 percent in excess of the country’s total potential renewable freshwater resources. WATER USE EFFICIENCY Considering that 98 percent of all agricultural raw materials in Iran are produced from irrigated lands it must be admitted that theoretically this is not a difficult problem to solve. Agricultural activities account for 94 percent of all water used in Iran. Since water use in the agricultural sector is inefficient, considerable improvement is possible through policy changes, technological solutions, and other alternatives. The situation is further complicated by the fact that agriculture is the major economic sector in Iran, and it will not be an easy task to convince the farmers of the need for water pricing policies to improve agricultural water management. Therefore, water management and development will be an increasingly challenging task in the near future. This is the main reason why more scientific cooperation and exchange of ideas and experiences is needed. PROBLEMS OF IRRIGATION AND DRAINAGE NETWORKS One of the problems of water management in Iran is the way that we view our irrigation and drainage projects. This vision does not coincide with the farmers’ indigenous knowledge of agriculture. The dry, high desert climate in the plateau of Iran and the scarcity of water resources in the area have forced farmers to develop special methods of using their limited natural resources with maximum care. They have tried to manage water and water resources using an understanding of nature that they have acquired through experience. The harmony they have established through the ages with natural processes has brought them a peaceful life through which they have been able to satisfy their needs despite

OCR for page 94
Water Conservation, Reuse, and Recycling: Proceedings of an Iranian-American Workshop limited resources, an inhospitable environment, and inadequate exploitation methods. Their struggle against nature has led to the accumulation of an indigenous knowledge base for conducting life and managing the environment. This indigenous knowledge has then served as a launching pad for further experience and acquaintance with easier and more efficient methods. Water exploitation methods are another facet of their life. Over the years these methods have evolved into what are known as current irrigation practices. These practices are the result of customs, practices, beliefs, knowledge, and experience that they have learned and put to use generation after generation. Unfortunately, the unilateral governmental vision to implement and manage irrigation and drainage projects in the past has been solely physical, and the participation of farmers or nongovernmental organizations has been neglected. The results of such a one-dimensional vision have been the disassociation of cultural and social relations between farmers and their system of irrigation. Even the physical development of irrigation and drainage projects has not been completed. Today, of the 26 bcm of water that are stored in reservoirs, only 17 bcm of water are used for agriculture, while 9 bcm are released just to operate hydropower units. Although the area of agricultural lands below the dams is 1.7 Mha, only 1.2 Mha of project area are equipped with main irrigation canals and 0.5 Mha are equipped with distribution canals. IRRIGATION TECHNOLOGY IN IRAN Operationally, the technology that has been adopted for new irrigation projects is not appropriate. It is true that the irrigation industry is not supposed to do original research and produce original technology. Rather, we look to the experience in other parts of the world and attempt to use good judgment and management, guided by the public interest, to transfer and apply the best available and most appropriate technologies. If technology transfer does not take place with a view to provisions for future developments and to the characteristics of our societies, it is doomed to cause irreparable damage. Such problems are now seen in the modern irrigation projects that have been constructed in Iran during the past 20 to 30 years. Developing countries are suffering from the consequences of improper use of technology more than developed countries despite the fact that developing countries are expected to have learned from the experience in industrial countries. The situation in developing countries stems from the fact that modern technology originated outside their boundaries, and with the import of technology the indigenous social system has also been intruded upon. Every technological import from industrial countries to developing countries has associated with it some unilateral colonialist interests for the exporter, but such technology transfers are more successful if the interests of both parties are secured. What this means is that all aspects must be considered in any case of technology transfer.

OCR for page 94
Water Conservation, Reuse, and Recycling: Proceedings of an Iranian-American Workshop Since technology is usually transferred to developing countries from outside, these countries can face more problems in providing the appropriate social changes to accompany technological developments than the industrial countries in which social development takes place simultaneously with technological development. In developing countries this integration takes time and money. It has been argued by many that if technology transfer is uncontrolled and independent of objectives or values, it will affect all aspects of our lives and sometimes make us slaves of technology rather than vice versa. A careful examination of the relationships between farmers and imported technology in modern irrigation projects of Iran reveals that when farmers have kept a safe distance from technology, they have maintained for themselves the right to choose an appropriate technology that enhances their goals. However, where this distance has disappeared, they have failed to exercise any control over their decisions, leaving them ultimately only the choice to either give up technology altogether or to follow not a progressive, but rather regressive path as dictated by technology. There have been some cases in the past in which an irrigation project has been constructed with a modern system of water distribution. But when the project was given to local farmers, some feature of the project was changed by them, because the new system was not appropriate to them, negating some of the intended benefits of the project. To avoid such catastrophic choices, technology and its relevance to each particular situation must be studied and then an appropriate form of technology must be introduced. APPROPRIATE TECHNOLOGY Over the past decade, technology has been increasingly in demand as a means of development. Particular technologies may be obtained in one of the following three ways: as finished technology from other countries, as imported technology but adapted to domestic needs, and as indigenous technology. In most cases a technology which requires a huge capital investment is cheaper to import than to develop, but the imported technology may not be fully applicable without some modification. Therefore, there is usually a mediating investment involved to balance or adapt the imported technology. This will increase its integration and applicability with the domestic situation. In cases where importing such technologies is not possible, it must be developed within the country based on indigenous knowledge. Indigenous knowledge is the integration of all accumulated personal, social, and historical experience. Indigenous knowledge concerning irrigation practices has accumulated and has been applied over thousands of years of experience in Iran. The study of indigenous knowledge and

OCR for page 94
Water Conservation, Reuse, and Recycling: Proceedings of an Iranian-American Workshop understanding of both positive and negative aspects of the relationship between humankind and nature can help us in the design and implementation of developing new projects. STATUS OF GROUNDWATER RESOURCES Groundwater is one of the most important water resources of Iran. One of the best methods of supplying water is digging qanats, a practice with a long tradition in Iran. Researchers have considered qanats to be an innovation developed by Iranians about three thousand years ago. A qanat initially consists of a well dug in a mountainside to reach the groundwater stored there. An underground tunnel is then dug from this point, directing the water to the village. Along the way to the village, some access wells are also dug at certain intervals, to provide access for later repairs and cleaning of the tunnel. Some of the main wells of the qanats systems in eastern Iran are more than 400 meters in depth, deep enough to hide the Eiffel tower. Their tunnels are longer than the equator. A great amount of water in Iran is supplied by qanats whose total length is estimated to be 160,000 kilometers. Unfortunately, most of the qanats have become dry due to exploitation of groundwater by pumps and wells. Groundwater balance shows that there is a difference of 4.8 bcm between recharge of groundwater resources (56.5 bcm) and discharges from them (61.3 bcm). The effect of this unbalance is evident in most of the valleys. Land subsidence, salt intrusion, and lowering of the water table are among the most prominent effects. The average drawdown of the water table in 168 valleys of the country, from which 73 percent of all withdrawals occur, is more than 1 meter per year. In some of the eastern provinces, more than half of the groundwater storage has been depleted. IRRIGATION EFFICIENCY A common perception is that irrigation wastes enormous amounts of water in Iran. It is commonly said that if irrigation could just be more efficient, water would be made available for more agriculture and other water uses, and there would not be as great a need to develop more water infrastructure. Unfortunately, this perception is in many cases not true, and the opportunity for real water saving through increased irrigation efficiency is much less than perceived. It is claimed that the overall irrigation efficiency in Iran is 30 to 35 percent. Briefly, the term “irrigation efficiency” (Ei) is used to define the amount of water that needs to be supplied from a source and delivered to the field (D) to meet water needs of crops (ET). Therefore, irrigation efficiency is calculated as Ei = ET/D. However, the data show that this may not be an accurate estimate. According to published agricultural statistics, the area under irrigation in Iran is 7.80 Mha. Of this total irrigated land area, 3.0 Mha are devoted to cereal, 2.0 Mha

OCR for page 94
Water Conservation, Reuse, and Recycling: Proceedings of an Iranian-American Workshop to orchards, and 2.8 Mha to different field crops. For irrigating these areas, 83 bcm of water is used. In comparison, it is reported that the average net irrigation requirements in Iran for cereal and field crops are 5,100 and 8,100 cubic meters per hectare (m3/ha), respectively. The Ministry of Energy, which is responsible for water allocation in Iran, has estimated the average amount of irrigation required to be 5,200 cubic meters per ha. The average of figures published by different consulting engineers is 5,900 m3/ha. Considering these figures, the overall irrigation efficiency in Iran will be somewhere between 48 and 55 percent, which is quite different from the figures that are presented officially or unofficially by various sources. Since the above figures are taken from various sources, we have to change our vision toward irrigation efficiency. If data for the area of irrigated lands are correct, then with an irrigation efficiency of 35 percent at least 120 bcm of water would be used, rather than the reported 83 bcm. If the reported volume of 83 bcm currently used for agriculture is right, then with an irrigation efficiency of 35 percent, the area under cultivation would be about 5.2 Mha rather than the reported 7.8 Mha. Based on the available data, the area that receives full irrigation in Iran is 2.5 Mha. Half of this area is equipped with modern systems of irrigation and is operated by government organizations. Irrigation efficiency in such systems is very low and is measured to be 20-30 percent. The reason for such low efficiency may be due to the free availability of water released from dams, giving no incentive to farmers to save water. The other half is operated by the private sector, and the water is supplied from groundwater resources. Here, also, the irrigation efficiency is rather low and has been measured to be about 35 percent. The rest of the irrigated farms in Iran belong to small farm holders who do not intentionally save water, but their irrigation efficiency is quite high. Irrigation efficiency in these farms is estimated to be 55-65 percent. The reason may be due to deficit irrigation, which they usually practice. These farmers have enough land, and the area under their cultivation is much greater than the water available to them. They usually get more benefit from extensive farming with deficit irrigation compared to intensive farming and full irrigation. Considering the above situation, the area under cultivation is balanced with the amount of water supply and demand. MAJOR PATHS TO SAVE WATER While the real irrigation efficiency in Iran is not low, many experts still believe enormous amounts of water are wastefully used in agriculture. Perhaps the major reason for the discrepancy is the way that the word “efficiency” is understood in irrigation. This efficiency may vary between 90 percent in the case of drip irrigation and 20 percent in traditional paddy irrigation systems. Thus, it is reasonable to think that increasing irrigation efficiency can save a large amount of water. In many cases it is possible but in other cases it is not. This possibility to increase irrigation efficiency depends on what happens to drainage water that

OCR for page 94
Water Conservation, Reuse, and Recycling: Proceedings of an Iranian-American Workshop is delivered to the field but not used by the crop for evapotranspiration. Drainage water may flow to the sea or desert, in which case it is effectively lost to further use. In this case, increasing irrigation efficiency will result in real water saving. On the other hand, drainage water may flow to other surface or subsurface areas where it can be captured and beneficially reused. This is what is called the return flow of water. Return flow may be a major source of recharge for aquifers in irrigated areas. One person’s drainage may be another person’s water supply. Thus, countrywide it is advisable to think in terms of basin efficiency rather than field efficiency, as the basin efficiency number is probably a better indicatior in terms of real water savings that can be made. By introducing the concept of basin efficiency, the effect of return flows is taken into account. In Iran, although the typical efficiency in full irrigation farms is 35 percent and in deficit irrigation farms is 55 percent, for the Iranian irrigation sector as a whole, at basin level it is high due to recycling. All things considered, there is not much real water saving to be made through improved irrigation efficiency in Iran, even though the system appears to be inefficient at first glance. The problem with the concept of increasing efficiency, even considering basin efficiency, is that the value of water is considered only in terms of physical quantities. Irrigation efficiency does not fully capture the value of water. This is the subject of the more general concept of increasing water productivity. AGRICULTURAL WATER PRODUCTIVITY Water productivity is simply defined as the amount of production per unit of water applied in the field. Water productivity can be increased by obtaining greater production with the same amount of water or by reallocating water from lower to higher value crops or from agriculture to other sectors where the marginal value of water is higher. Indeed, the greatest increases in the productivity of water in irrigation have not been from better irrigation systems but rather from increased crop yields due to better management. For this reason, it is generally best to use the term water productivity, rather than efficiency. A key to mitigating the problem of water scarcity in Iran is increasing the productivity of water. Let us consider agriculture, as there is a tremendous need to produce food, mainly grains, from water resources. There are generally four paths of generating more agricultural output from national-level utilizable water resources as follows: increase utilizable water, develop more primary water (increase in development of facilities), consume more of the developed water beneficially (increase in basin efficiency), and produce more output per unit of water consumed (increase in water productivity).

OCR for page 94
Water Conservation, Reuse, and Recycling: Proceedings of an Iranian-American Workshop Opportunities to increase agricultural water productivity via the first two approaches are very limited in Iran. If we do not consider the incoming international water, the total amount of renewable water will not exceed 117 bcm, from which only 105 bcm can be controlled as utilizable water. For the third approach, it may be feasible to improve water conservation in those areas that receive full irrigation. By proper water management and improvements in water distribution networks, irrigation efficiency may increase up to 50 or even 60 percent. As a result, the area of these fully irrigated lands may increase from 2.5 Mha to 3.5 or 4.3 Mha, respectively. Although it is also possible to increase irrigation effectiveness in those areas that receive deficit irrigation, no increase in cultivated area could be expected. Thus, the major solution will be the fourth approach, increasing water productivity. In agriculture, water is consumed as evapotranspiration, which is essential for crop production. As Smith (1999) stated, the process of converting water into yield is referred to as the eco-physiological water use efficiency or crop water productivity (CWP). Crop water productivity can be defined as the kilograms (kg) of yield per unit of consumed water (ET), or CWP = kg / ET. An extensive data set of studies carried out worldwide has shown that global values for CWP are very low for some crops (Doorenbos and Kassam, 1979) and generally high for some other crops like tomatoes. The genetic characteristics of the crop are the primary factors determining CWP. A secondary factor that in various ways affects CWP is the reaction of the crop to water stress. For cereal grains, water productivity ranges between 0.2 and 1.5 kg (grain)/ m3(water) (Molden et al., 1999). Based on area under cultivation and the amount of grain yield in the Khorasan Province of Iran, water productivity for this crop is about 0.7 kg/m3, which is quite low compared to a similar environment like the Imperial Valley of California. The Imperial Valley is situated in a desert environment like Khorasan Province. The range in wheat yield in these areas is from 2 to 6 tons per hectare. Within the Khorasan Province, there is a great variability in yield, with some farmers achieving productivity levels as high as those in California and some farmers well below the average. Of course, production levels also depend on environment, market, soil, and other conditions that are not identical in any two sites. In spite of these differences, there appear to be opportunities to manage resources to achieve greater productivity. As a rule of thumb, a reasonable level of water productivity for wheat is about 1.0 kg/ m3. Therefore, if the demand for grain grows by 50 percent in the country by 2020, one way to match this increase is to increase water productivity by 50 percent. Water use efficiency is a combination of water productivity, which is a biological factor, and irrigation efficiency, which is a physical factor. Therefore, the menu of options for improving water use efficiency includes a combination of measures in four different areas as follows:

OCR for page 94
Water Conservation, Reuse, and Recycling: Proceedings of an Iranian-American Workshop Technical practices, such as land leveling for uniform distribution of water on land. Institutional practices, such as establishing a water user organization, reducing irrigation subsidies, and fostering rural infrastructure for private sector dissemination of appropriate, efficient technology. Agronomic practices, such as developing varieties of crops that yield more mass per unit transpiration, substituting crops that consume less water for crops that consume more water, intercropping to maximize use of soil moisture, and selecting drought tolerant crops where water is scarce. Managerial practices, such as better irrigation scheduling, recycling of drainage and tail water, and precision irrigation. Precision irrigation refers to a combination of technologies and associated management practices that can help overcome the problems of quantity and timing of irrigation supply. For example, drip, sprinkler, and level basin techniques enable control of water applications and can contribute to achieving higher crop yield. The results of experiments carried out at Khorasan Agricultural Experiment Station on melon, tomato, sugar beet and watermelon showed that precise drip irrigation can increase water use efficiency up to three times. It should be remembered that precision irrigation does not imply expensive high technology irrigation. Instead, it refers to a broad range of technologies and water management practices that enable farmers with limited access to water to apply water to their crops in the time and quantity that increase the productivity of water. Precision irrigation can even be practiced with existing conventional technologies. Recent development of a mechanized pot system of irrigation in Iran has shown that this system tremendously reduces irrigation requirements, and it successfully has been used for irrigation of orchards (such as pistachio), vegetables, and green houseplants. SELECTED BIBLIOGRAPHY Alizadeh, A., G.H. Kamali, and I. Malek-Mohammadi. 2001. Sustainable utilization of saline water in agriculture based on indigenous knowledge. International symposium on prospects of saline agriculture in the GCC countries, Dubai, United Arab Emirates. Biswas, A.K. 1998. Deafness to global water crises. Causes and risks. Ambio 27(6):93. Doorenbos, J. and A. Kassam. 1979. Yield response to water. Rome: FAO Irrigation and Drainage Paper 33, p. 193. Falkenmark, M. 1999. Forward to the future. A conceptual framework for water dependence. Ambio 25(3):211-212. Ghazi, I. 2002. Water resources management and planning in Iran. Report to the University of Isfahan. Molden, D. and C. de Fraiture. 1998. Major path to increasing the productivity of irrigation water. Chapter 4, Draft 14-5-98. International Water Management Institute (IWMI), Sri Lanka. Plan and Budget Organization, 1999. Document of the Third Plan, Volume 1. Iran Ministry of Water and Power, Tehran.

OCR for page 94
Water Conservation, Reuse, and Recycling: Proceedings of an Iranian-American Workshop Reza, A., Kooros, Ch., Emam-Shooshtari, M., and A. Entezami, 1973. Water and irrigation technique in ancient Iran. Ministry of Water and Power, Tehran. Sally, H., Sakthivadivel, R. and D. Molden, 1999. More crop per drop. 6th International Micro-irrigation Congress, Cape Town. Seckler, D., A. Marasinghe, U. Molden, D. de Silva, R. and R. Barker, 1998. World water demand and supply, 1990 to 2025: Scenarios and issues. IWMI, Sri Lanka. Smith, M. 1999. Optimizing crop production and crop water management under reduced water supply. 6th International Micro-irrigation Congress, Cape Town.