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Water Conservation, Reuse, and Recycling: Proceedings of an Iranian-American Workshop Water Allocation and Pricing in Agriculture of Iran Abbas Keshavarz, Shahram Ashraft1, Nader Hydari1, Morteza Pouran1, and Ezzat-Allah Farzaneh1 ABSTRACT Limited water resources and world population growth have caused a shortage of agricultural products in some countries. Currently, this limitation is one of the most serious problems in Middle Eastern countries, especially arid and semiarid countries. Considering population growth rates and limited water resources in the world, it is anticipated that food security will be a serious challenge in coming decades. The agricultural sector in Iran is one of the most important economic sectors of the country, and water is the most limiting factor for production. More than 90 percent of the renewable water in the country is used in agriculture, but its production is insufficient to meet the country’s demand. Because of low irrigation efficiency, about 50 to 60 percent of renewable water is lost in agriculture, and this has caused agricultural water productivity to be very low. Efficient application of water in agriculture is one of the most important contributing factors to producing as much food as is required at present and in the future. Proper planning, management, and education in this sector would help prevent the waste of limited natural resources. Efficient application of water in the country, therefore, is one of the most important policies of the government of the Islamic Republic of Iran (I.R. Iran). 1 Scientists of Iranian Agricultural Engineering Research Institute.
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Water Conservation, Reuse, and Recycling: Proceedings of an Iranian-American Workshop INTRODUCTION Iran is located in the Northern Hemisphere, between 25° and 40° N and 44° to 63° E. Agriculture plays an important role in the economy of Iran. It accounts for one fourth of the Gross Domestic Product (GDP), one fourth of employment, more than 80 percent of food requirements, one third of non-oil exports, and 90 percent of raw materials for industries. The agriculture of I.R. Iran enjoyed an average growth rate of 5.1 percent over the two National Development Plans (1989 to 1999). Out of the 165 million hectares that comprise the country’s area, about 37 million hectares are suitable for irrigated and dryland agriculture, of which 20 million hectares are irrigated and 17 million hectares are dryland. Of the 37 million hectares of agricultural lands, currently 18.5 million hectares are devoted to horticulture and field crop production. Of these, 6.4 million hectares are under annual irrigated crops, 2 million hectares are under horticultural crops, and about 6.2 million hectares are under annual dryland crops, while the remaining 3.9 million hectares are fallow. The total natural resources and rangeland areas are about 102.4 million hectares, composed of 90 million hectares as pastures (in various level of forage productivity) and 12.4 million hectares as forests. CLIMATE, RAINFALL, AND EVAPORATION The Islamic Republic of Iran is situated in one of the most arid regions of the world. The average annual precipitation is 252 mm (one-third of the world’s average precipitation), and this is under conditions in which 179 mm or 71 percent of rainfall is directly evaporated. The annual evaporation potential of the country is between 1500 and 2000 mm. Unfortunately, in the past six years, particularly in the year 2000, some parts of the country have suffered severely from drought. Altitudes vary from 40 m below sea level to 5,670 m above sea level and have a pronounced influence on the diversity and variation of the climate. Although most parts of the country can be classified as arid to semiarid, the country enjoys a wide range of climatic conditions. Both latitude and altitude have a major influence on climate in the various regions. This can be seen in the geographic variation of annual precipitation (from 50 mm in the central desert to 1600 mm in Gillan Province, situated at the southern coast of the Caspian Sea), and a wide range of temperatures that can vary up to 100°C (from –44°C in Borudjen/Chahar Mahal Bakhtiari Province, located in the central Zagrus Range mountains to 56°C in the south along the Persian Gulf coast). Distribution of precipitation in Iran is presented in Table 1.
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Water Conservation, Reuse, and Recycling: Proceedings of an Iranian-American Workshop TABLE 1 Distribution of Precipitation in Iran Annual precipitation (mm) Area (km2) Percent <50 100,000 6 50-100 285,000 17 100-200 456,000 28 200-300 370,000 23 300-500 280,000 17 500-1000 130,000 8 >1000 18,000 1 Total 1,648,000 100 WATER RESOURCES AND WATER USE The main source of water in Iran is precipitation of both rainfall and snow (70 percent rainfall and 30 percent snow). Total precipitation is estimated to be about 413 billion cubic meters (bcm), of which about 71.6 percent (295 bcm) directly evaporates. By taking into account 13 bcm of water entering from the borders (joint border rivers), the total potential renewable water resources have been estimated to be 130 bcm. Currently, the total water consumption is approximately 88.5 bcm, out of which more than 93 percent is used in agriculture, while less than 7 percent is allocated for urban and industrial consumption (Table 2). Under the present situation, 82.5 bcm of water are utilized for the irrigation of 8.4 million hectares of irrigated agriculture (horticulture and field crops). About 1.4 million hectares of these areas are managed by regulated flow (irrigation networks); 6.7 million hectares by means of traditional networks, and less than 300,000 hectares under a pressurized system. Surface water resources provide 37.5 bcm of water for different consumption purposes (about 42 percent of the total water consumed) in the country. The existence and importance of groundwater has been known and understood for TABLE 2 Estimated Consumption of Water in Iran (Year 1998) Consuming Sector Consumption (bcm) Percent of total Agriculture 82.5 93.22 Urban 5.6 6.32 Industry 0.03 0.03 Miscellaneous 0.37 0.43 Total 88.5 100
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Water Conservation, Reuse, and Recycling: Proceedings of an Iranian-American Workshop thousands of years. The traditional method of groundwater extraction is Qanat, which brings water to the surface by gravity. In recent years more than 50,000 wells of various types have been dug and used for extraction of groundwater from the aquifers. More than 60 percent of total water consumption in the country (51 bcm) is extracted from groundwater resources. Due to inefficiency of traditional irrigation methods and water conveying systems, about 63 percent of the valuable water is lost, and in practice only 37 percent of available water is utilized in agricultural production. SOCIOECONOMIC ASPECTS Agriculture in Iran is run privately, with 99 percent of the agricultural lands being managed and commodities being produced by the private sector. Out of a total population in Iran of 65 million, about 24 million (38 percent) live in rural areas (roughly 60,000 villages). Thirty years ago, in the 1970s, the rural to urban ratio was almost the reverse. Between 1976 and 1998, the rural population increased from 17.9 million to 23.6 million. Out of 14.2 million job opportunities throughout the country, 3.3 million (23 percent) are in the agricultural sector. The distribution of the rural population is largely determined by the availability of water, rainfall, and arable lands. Thus, with the exception of the well-watered Caspian Sea area with its high rainfall, most settlements are isolated and scattered through arid and semiarid regions in the plains and mountains. More than 90 percent of the 2.6 million rural agricultural households possess land, and a great majority of these are small and medium farms, which dominate Iranian agriculture. A high proportion of farms in Iran are considered small in size. About 78 percent of farmers have farms of less than 10 hectares in size, and 11 percent are less than one hectare. While farms less than 10 hectares make up about 37 percent of the cultivated land, represent about 12 million of the rural population, and produce a similar proportion of the agricultural gross output, they produce less than 10 percent of marketed agricultural production. This is accounted for by the fact that small farmers have low income, and many of them are mainly subsistence farmers with no surplus products for sale. Farms over 10 hectares provide about three-quarters of the market supplies. Large farms (over l00 hectares), currently only make small contributions to the agricultural output of Iran. The national farm-size distribution for irrigated and dryland agriculture in Iran is presented in Table 3. Farms less than 10 hectares account for a greater percentage of the irrigated areas. AGRICULTURAL PRODUCTION IN IRAN The production of horticulture and field crops in the decade from 1988 to 1998 experienced positive changes. These changes were due mainly to the imple-
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Water Conservation, Reuse, and Recycling: Proceedings of an Iranian-American Workshop TABLE 3 National Farm-size Distribution (Irrigated and Dryland Agriculture) Size (ha) Total Area (kha) Area (percent) Percentage Irrigated Dryland Average Size (ha) < 1 196 1.6 3.1 0.3 0.4 1-2 423 3.4 5.7 1.4 1.1 2-5 1,630 13.0 17.4 9.3 2.4 5-10 2,371 18.9 20.4 17.6 4.8 10-25 4,467 35.5 29.1 40.7 9.8 25-50 1,585 12.6 10.0 14.7 21.2 5-100 961 7.5 6.2 8.8 41.8 Over 100 947 7.5 8.0 7.1 118.5 Total 12,580 100 100 100 4.9 mentation of the results of research findings and extension activities that contributed to increased yield per unit area. The other factor that caused change was utilization of unused land capacities through development and expansion of areas under cultivation. The average annual growth rate of agricultural production was 5.1 percent during the period from 1988-1998. The total agricultural production for various commodities from 1988-1998 is presented in Table 4. During the same period wheat production increased from 7.2 million tons to 11 million tons, corn grain from 0.143 million tons to 0.941 million tons, and vegetables and horticulture crops from 5.4 million tons to 11.6 million tons. It is noteworthy that the 1998 growing season was an exceptional year in terms of both the amount and distribution of precipitation. Unfortunately, in the last three TABLE 4 Agricultural Production in Various Commodities during Years 1988-1998 Agricultural Products 1988 (in million tons) 1998 (in million tons) Field Crops 28.60 53.30 Irrigated 25.85 44.73 Dryland 2.75 8.57 Horticultural Crops (Fruits) 7.20 11.60 Milk 3.40 5.10 Red Meat (lamb and beef) 0.51 0.75 Chicken 0.30 0.70 Eggs 0.26 0.50 Fish 0.24 0.40
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Water Conservation, Reuse, and Recycling: Proceedings of an Iranian-American Workshop years (1999-2002), particularly in 2002, drought has seriously threatened some parts of the country, and agricultural production decreased about 8-10 percent. Annual crop groups and horticultural crops and their areas under cultivation and production are presented in Tables 5 and 6, respectively. TABLE 5 Cultivated Areas and Total Production of Different Crops under Irrigated and Dryland Conditions in 1998 in Iran Cultivated areas (kilohectares) Total Production (kilotons) Crop Groups Irrigated Dryland Total Irrigated Dryland Total Cerealsa 3,706 5,069 8,775 13,453 5,513 18,967 Pulsesb 173 785 957 250 327 577 Industrial Cropsc 590 132 751 7,629 140 7,769 Vegetablesd 423 35 458 9,730 428 10,158 Summer Cropse 288 47 335 5,316 277 5,593 Forage Cropsf 786 152 938 8,899 1,179 10,078 Total annual crops 5,966 6,220 12,186 — — — Horticulture (orchards) 1,777 188 1,965 11,397 263 11,660 Total 7,797 6,501 14,296 56,796 8,176 64,073 aCereals: wheat, barley, paddy, and corn grain. bPulses: pea, bean, lentil, Fava bean, and other pulses. cIndustrial crops: cotton, sugar beet, sugarcane, and oil seeds. dVegetable crops: potato, onion, tomato, eggplant, etc. eSummer crops: melon, watermelon, cucumber, etc. fForage crops: alfalfa, clover berseem, and forage corn. TABLE 6 Cultivated Areas and Total Production of some Horticultural Crops in 1998 Crops Cultivated Areas (kilohectares) Production (kilotons) Apple 163 2,137 Grape 288 2,342 Pistachio 361 131 Citrus 234.5 3,934 Date Palm 215.7 908 Pomegranate 55 604 Tea 34 270 Nutsa 217 250 Olive 30 24 Othersb 403 987 Total 2,000 11,600 aAlmond, Walnut, Hazelnut. bPear, Peach, Cherry, Apricot, Strawberry, Kiwifruit, Fig, Saffron, etc.
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Water Conservation, Reuse, and Recycling: Proceedings of an Iranian-American Workshop EVALUATION OF WATER USED IN AGRICULTURE Water use in agriculture in Iran may be evaluated in terms of irrigation efficiency and agricultural water productivity. Irrigation Efficiency First of all the authors acknowledge that the discussions in this section are based on personal communication with irrigation experts and research studies in the country that might differ in some ways from official reports. A common perception is that irrigation water is wasted considerably in Iran. Studies have shown that the overall irrigation efficiency in Iran ranges from 33 percent to 37 percent, which is lower than average worldwide irrigation efficiency. This rate of irrigation efficiency indicates that the average consumption of irrigation water in the country is high compared to worldwide consumption of irrigation water. Comparisons between the application of irrigation water in Iran and worldwide application for different crops are shown in Table 7. In 1999 the Iranian Agricultural Engineering Research Institute (IAERI) conducted a research project on the on-farm water application efficiency for different crops. The results obtained from field experiments in different provinces showed that the application efficiency depends on farm management, method of irrigation, growth stage, and type of crop, and it varied from 24.7 percent to 55.7 percent. Considering the conveyance efficiency in the target area of the research study, the overall irrigation efficiency varied between 15 and 36 percent. Based on results obtained from studies and research conducted by different water organizations for determining overall irrigation efficiency, IAERI has published the concerned national document in 2000 (Dehghani S.H, A. Alizadeh and A. Keshavarz, 1999). The overall irrigation efficiency in different provinces in the country is presented in Table 8. As is shown in this table, there is a range of overall irrigation efficiencies for each province; the irrigation efficiency varies from a low to a high value based on the source of water and type of irrigation TABLE 7 Average Application of Water for Different Crops Worldwide and in Iran (1994) Crops World (m3/ha) Iran (m3/ha) Wheat 4,500-6,500 6,400 Melons 7,000-10,500 17,900 Sugar beet 5,500-7,500 10,000-18,000 Rice 4,500-7,000 10,000-18,000 Sugarcane 15,000-25,000 20,000-30,000 Corn 5,000-8,000 10,000-13,000
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Water Conservation, Reuse, and Recycling: Proceedings of an Iranian-American Workshop TABLE 8 Ranges of Irrigation Efficiency in some Provinces in Iran No Provinces Range of Irrigation Efficiency (%) 1 West Azerbaijan 28-41 2 Ardabil 28-39 3 Isfahan 28-42 4 Boshehr 24-30 5 Chaor-Mahhal-Bottiari 30-39 6 Korasan 30-37 7 Kozestan 27-37 8 Zanjan 25-38 9 Semnan 30-40 10 Gazvin 27-38 11 Kordestan 25-40 12 Glolestan 28-40 13 Gillan 38-54 14 Mazanderan 37-57 15 Markazi 29-39 16 Hamedan 27-38 17 Yazd 30-40 management applied for the distribution of water to the farms. The source of water may be surface water, shallow wells, qanats, and springs, and the distribution networks may be modern or traditional irrigation networks. Considering overall irrigation efficiencies in different provinces (Table 8) and different published reports and research studies, the irrigation efficiency in the country is estimated to be 35 percent, which is very low compared to developing countries (45 percent) and developed countries (60 percent). According to published agricultural statistics, the areas under irrigation in Iran total 8.4 million hectares (Mha). For irrigation of these areas, 82.5 bcm of water is used. In contrast, the international water management institute (IWMI) has reported that the average net irrigation requirement in Iran for cereal and field crops is 5,100 and 8,100 cubic meters per hectare (m3/ha), respectively. The Ministry of Energy, which is in charge of water allocation in Iran, has estimated the average amount of irrigation requirement to be 5,200 cubic meters per hectare. The average of figures that have been published by different consulting engineers is 5,900 m3/ha. Based on these figures, the overall irrigation efficiency in Iran is between 48 and 55 percent, which is quite different from the figures that are presented officially or unofficially by various sources. Based on available data, the areas that receive full irrigation in Iran total 5 Mha. At least 1.6 and 1.8 Mha of the irrigated areas are suffering from severe and moderate water stress, respectively.
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Water Conservation, Reuse, and Recycling: Proceedings of an Iranian-American Workshop Half of the fully irrigated areas are equipped with modern irrigation systems and operated by governmental organizations. Irrigation efficiency in such systems is very low and is measured at 20-30 percent. Irrigation efficiency may be so low due to the free availability of water released from dams, there being no incentive for farmers to save water. The other half of fully irrigated areas are operated by the private sector, and the water is supplied from groundwater resources. In this case, the irrigation efficiency is also rather low and has been measured to be about 35 percent. The rest of the irrigated farms in Iran, which are under severe to moderate water stress, belong to small farm holders who do not save water, but their irrigation efficiency is quite high. Irrigation efficiency in these farms is estimated to be 55-65 percent. The reason for this may be due mainly to reduced 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 receive more benefit from their extensive farming with reduced irrigation in comparison with those who practice intensive farming and full irrigation. AGRICULTURAL WATER PRODUCTIVITY Water productivity is simply defined as the amount of production per unit of water. 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 one section of the agriculture sector to another, where the marginal value of the water is higher. Indeed, the greatest increases in productivity of water in irrigation have not been from better irrigation systems, but rather from increased crop yields due mainly to better management. 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 approaches for generating more agricultural output from utilizable water resources as follows: increasing utilizable water, developing more primary water (increase in development of facilities), consuming more of the developed water efficiently (increase in basin efficiency), and producing more output per unit of water consumed (increase in water productivity). Opportunities to increase agricultural water productivity via the first two approaches are very limited in Iran. For the third approach, it may be feasible to improve water conservation in those areas that receive full irrigation. By proper water management and completion of water distribution networks, irrigation
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Water Conservation, Reuse, and Recycling: Proceedings of an Iranian-American Workshop efficiency is expected to increase by 50 to 60 percent. As a result, the areas of these lands may increase from 2.5 Mha to 3.5 and 4.3 Mha, respectively. Although it would also be possible to increase irrigation effectiveness in those areas that receive reduced irrigation, no significant increase in cultivated areas could be expected. Thus, the major solution will be the fourth approach, which is to increase water productivity. This is especially appropriate in the areas where water application is much higher than water requirements of the crops, as estimated by the soil water balance during the growing season in different field studies. Crop water productivity (CWP) 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 (Doorenbos and Kassam, 1979) has shown that CWP is very low for some crops, like sunflower, but for other crops like tomato it is generally high. The genetic characteristics of the crop are the primary factor determining CWP. A secondary factor that affects CWP in various ways is the reaction to water deficit. For instance, CWP for wheat in Khorasan Province of Iran is about 0.5 kg/m3, which is quite low compared to a similar environment like the Imperial Valley in California or even Bhakra in India. The CWP for different agricultural crops in Iran is shown in Table 9. As a rule of thumb, a reasonable level of wheat productivity is about 1 kg/m3. Therefore, if the demand for grain grows by 50 percent in the country by 2020, one way to meet this demand is to increase water productivity by 50 percent. DEMAND FOR FOOD AND AGRICULTURAL PRODUCTS Studies have shown that despite population increases from 1988-1998, the agricultural production per capita index has increased remarkably to 137 per- TABLE 9 Measured Crop Water Productivity at Different Regions in Iran Crop Irrigation Method Yield (kg) Applied Water (m3/ha) Water Productivity (kg/m3) Wheat Furrow-border 5,460 9,900 0.55 Barley Furrow 6,090 6,120 1.00 Sugar beet Furrow-border 37,700 14,500 2.60 Potato Furrow 37,100 5,140 7.21 Corn Furrow 7,000 1,080 0.65 Alfalfa Basin-border 10,500 11,660 0.90 Beans Furrow 5,100 5,600 0.91 Sesame Furrow 1,432 7,000 0.20 Tomato Furrow 16,000 4,800 3.33 Lettuce Furrow 4,100 8,600 4.77
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Water Conservation, Reuse, and Recycling: Proceedings of an Iranian-American Workshop cent. The agriculture sector has produced 80 percent of the food supply in the past decade. The energy supply per capita from 1988-1998 was 2,900 calories. According to international standards, the daily energy requirement is 2,300 calories per capita. Food supply in Iran consists of 72 percent carbohydrates, 17.5 percent fat, and 10.4 percent protein. In comparison, a desirable composition is 55-75 percent carbohydrates, 15-30 percent fat, and 15-20 percent protein. About 85 percent of energy and 76 percent of protein in the Iranian diet is provided by 10 food commodities, which include bread, rice, vegetable oil, sugar, chicken, pulses, milk and its by-products (cheese and yogurt). These are called basic commodities in the Iranian diet. Around 65 percent of total food expenditures are spent on these items. Bread alone provides 40 percent of the energy and 45 percent of the protein in the Iranian diet; therefore, wheat is the staple component of Iranian daily food. However, improvements in the food consumption pattern should be made in coordination with the domestic production potential. SHORT TERM AGRICULTURAL SCENARIO The agriculture sector supplies most of the food requirements in Iran; however, it is not yet self sufficient. The average quantity of major commodities that were imported annually, during 1988–1998, are presented in Table 10. Iran’s population is expected to increase from about 63 million in 2000 to 70 million people by 2005. Challenges in the future include domestic food supply as well as improvement in food consumption patterns. In the short term, which coincides with the Third Five-Year Development Plan (2001-2005), objectives and highlights of the agriculture program can be summarized as follows: Improving quality and quantity of agricultural products (annual crops, fruits, livestock, poultry, fisheries, and aquaculture) through efficient and sustainable use of natural resources, while approaching food security. Priorities are given to strategic crops, including cereals, oil seeds, olives, maize, forage crops, fisheries, and export extension for horticultural products. TABLE 10 Major Commodities Imported During 1988-1998 (Annual Average) Commodity Amount Unit Wheat 3.4 million tons Rice 600 kilotons Barley 500 kilotons Maize 1.2 million tons Sugar (raw) 840 kilotons Oil crops 750 kilotons Meat 520 kilotons
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Water Conservation, Reuse, and Recycling: Proceedings of an Iranian-American Workshop Drafting and completion of all food safety related standards to improve the health status of society. Implementing various policies, including determination of a suitable model for sustainable development. This is planned to be developed based on current needs and capacities and on comparative advantages of increasing yields through efficient use of land and water resources. Innovative approaches to increase use of certified seeds, optimize application of pesticides and fertilizers, and expand development of mechanization are other aspects of these policies. Improving activities related to soil moisture conservation and retention, watershed management, and protection of agricultural land. The geographic location of Iran makes it very vulnerable in terms of its annual precipitation. This factor makes utilization of dryland agriculture with low yields very difficult. The highest priority, therefore, is introduction of drought resistant varieties of crops for irrigated and dryland areas to increase water use efficiency and water productivity. Agricultural products are expected to increase from 60 million tons in 2001 to 90 million tons by 2004. Currently, total production of irrigated crops is 57 million tons, while total water supply for agriculture is 83 bcm. Therefore, water productivity is 0.7 kg/m3. By the year 2005, total production of irrigated crops is expected to reach 90 million tons, while total water supply will be about 90 bcm so projected water productivity is estimated to be 1 kg/m3 of water. CHALLENGES IN THE 21ST CENTURY By 2020 Iran’s population is estimated to reach 100 million. However, total agricultural production is expected to be 200 million tons, of which 189 million tons will be harvested from irrigated crops. Total water supply for agriculture will be about 100 bcm. This means that by the year 2020, water productivity should reach 1.9 kg/m3. To fulfill this expectation, agricultural commodities (wheat, barley, maize, oil crops) will be the main focus for improvements. With opportunities for expanding areas under cultivation almost exhausted, additional food production will have to be accomplished mainly through increasing productivity. Demand for major agricultural products by the year 2020 is presented in Table 11. Intensive use of water, fertilizers, and other agricultural inputs for crop production at present are the major cause of problems in soil and groundwater salinization, nutrient imbalances, incidence of new pests and diseases, and environmental degradation. Rising biotic pressure, lack of a suitable soil management system, and lack of inputs to realize optimum potential of land appear to threaten sustainability of agriculture. Thus, the consequences are degraded lands, loss of biodiversity, soil
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Water Conservation, Reuse, and Recycling: Proceedings of an Iranian-American Workshop TABLE 11 Demand for Major Agricultural Products, Comparing Production in 1998 with Projected Demand in 2020 Commodity Production (1988) (million tons) Demand (2020) (million tons) Wheat 10.00 17.50 Rice (Paddy) 2.70 4.90 Maize 0.90 4.30 Pulses 0.68 1.75 Oil seed 0.24 3.80 Potato 3.30 14.00 Forage crop 7.98 24.10 Apple 2.10 12.00 Grape 2.34 5.70 Pistachio 0.13 0.75 Citrus 3.90 7.30 Date-palm 0.91 3.00 Tea 0.27 0.40 Olive 0.02 1.30 erosion, deforestation, and overall environmental pollution, all of which result in lowered productivity. For efficient and sustainable agriculture it will be essential to shift from a commodity-centered approach to a farming-systems approach, which calls for multidisciplinary efforts. This will require emphases on efficiency, sustainability, post-harvest management, mechanization, marketing, and trade. Such an approach will also require forging links with all who are concerned at the regional, national, and international levels. With implementation of these new approaches, water productivity should be increased to at least 1.9 kg/m3. This implies that the institutional structure and procedures of water allocation in the agriculture sector should be modified. This would necessitate emphases on special prioritization, policies, modernization, water use efficiency, and productivity management. To elaborate more on the importance and role of water, and to draw the necessary attention for improving water productivity in the future, the main agricultural criteria in an index year (2000) and short and long horizons are presented in Table 12. As shown in Table 12, the possible increase in water resources is very limited (9.7 and 22 percent after 5 and 22 years, respectively). However, in order for agricultural products from the irrigated land to increase significantly (by 150 and 337 percent by 2005 and 2020, respectively), water productivity (0.7 kg/m3) has to be increased to 1 and 1.9 kg/m3 by 2005 and 2020, respectively.
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Water Conservation, Reuse, and Recycling: Proceedings of an Iranian-American Workshop TABLE 12 Main Agricultural Criteria of Iran at Index year (2000) and Short and Long Horizons Year Criterion 2000 2005 2020 Population (million) 63 70 100 Volume of water allocated to the agriculture sector (billion cubic meter) 82.5 90 100 Total types of products of irrigated lands 56 85 189 Water productivity (kg/m3) 0.7 1 1.9 Increase in allocated water (%) — 9.7 22 Expected increase in the products of irrigated lands (%) — 150 337 Percent of total water allocated to the agriculture sector 93 93 93 OBJECTIVES AND CHALLENGES As shown in Table 12, it is anticipated that agricultural products from irrigated areas will increase from 56 million tons in 2000 to 85 million tons in 2005 and 189 million tons in 2020. This would be realized when our water resources can be increased up to a maximum of 10-22 percent. Therefore, it is necessary to increase water productivity in agriculture from 0.7 kg/m3 in 2000 to 1.9 kg/m3 by 2020. The expected increase in agricultural products basically depends on the country’s available water resources. Water scarcity is the most limiting factor in agricultural productivity in Iran. Attention to improvements in water supply and water productivity programs has been the most important and governing policy during the past 22 years. Under this policy, different rules have been applied and, in addition, different technical infrastructures (executive, research, and consultative) in both public and private sectors have been developed. This attention, in addition to establishment of special laws and regulations, has been considered in the construction of development programs. Among the established laws which can be nominated are the Balanced Distribution of Water law (established in 1983) and the Executive Instructions of Optimization of the Agricultural Water Consumption. The above mentioned law is a focal point in the evolution of viewpoints on water issues in I.R. Iran. The basic objectives of this law are as follows: Optimum use of water resources in agriculture through optimizing consumption. Volumetric distribution of water based on irrigation requirements in the different regions.
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Water Conservation, Reuse, and Recycling: Proceedings of an Iranian-American Workshop Introduction of suitable cropping patterns (relative to water productivity). Improvement of irrigation management. The first step in fulfillment of these objectives is determination of water requirements of different crops in the different regions. Provision of suitable cropping patterns, and determination of expected irrigation efficiency in different time periods would be the next step. Carrying out these steps in terms of volumetric water distribution and consumption, and developing suitable water pricing policies in local and regional operation and management of irrigation networks, have as their aim the optimization of agricultural water consumption. The following sections summarize actions taken to optimize agricultural water consumption. Many of these actions are documented as the National Water Document, certified by the government of Iran (Ministry of Agriculture, 1998). ESTIMATION OF CROP WATER REQUIREMENTS Determination of the water requirement of crops is the basic measure in irrigation and water resource planning. In the past 50 years widespread and extensive research has been conducted worldwide, and as a result more operational as well as accurate procedures for estimation of crop water requirements are available. These research findings have contributed to better recognition of the physical and biological processes of evapotranspiration. On the basis of these findings, models and practical procedures for estimating crop water requirements have been developed. From the wide variety of studies carried out using different methods and under various climatic conditions throughout the world, it is necessary to select those that have the greatest applicability to the climate and geophysical conditions in Iran. There has been much discussion about which method of estimating evapotranspiration of field crops (ETC) and crop water requirements is the most accurate. The results of a study to determine irrigation and water requirements conducted by the American Society of Civil Engineers (ASCE) and the Society of European Commission in a consortium of research institutes have shown the superiority of the Penman-Monteith method over other methods for the estimation of crop water requirement. These results have shown that the Penman-Monteith method (Monteith, 1965, and Penman, 1948) with a 4 percent overestimate in wet regions and 1 percent underestimate in dry regions (compared with lysimetric data), is the best method for ETC estimation. The Penman-Monteith method was selected as the best method to use for determining crop water requirements as part of formulating a National Document of crop water requirements in Iran (Ministry of Agriculture, 1998). To arrive at this decision, consultations took place between the Ministry of Jihad-e-Agriculture (Agricultural Engineering Research Institute, AERI, and the Soil and Water Research Institute, SWRI), Deputy of Soil and Water of the Meteoro-
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Water Conservation, Reuse, and Recycling: Proceedings of an Iranian-American Workshop logical Organization, and other interested organizations, as well as contributing universities. These consultations occurred under the leadership and supervision of an expert committee. To develop these national crop water requirements, a computer program was prepared for calculation of daily evapotranspiration (ETo) based on the Penman-Monteith method. This program uses existing data from the Meteorological Organization, consisting of daily readings from multiple stations, to calculate ETo values and store them in another file. Since the number of statistical years varies for different weather stations, a statistical index period of 25 years (1970-1995) was developed and daily ETo for each station was calculated. In this manner, a total of 9,125 different ETo values were calculated. For stations where the period of record was less than 25 years, statistical methods were used to standardize the existing data to the 25-year index period. A total of 363 climatic stations were utilized for this study. The Penman-Monteith method was applied to data from these 363 stations. After calculating for each statistical year, the average of 25 years of crop water requirements for each day of the year was computed. In order to evaluate the results of the Penman-Monteith method, ETo was calculated using nine other conventional methods. The results were compared with one another to facilitate understanding any wide differences. There are 618 plains or agricultural areas in Iran that have been investigated and categorized for the Comprehensive Agricultural and Watershed Basins Project as part of the Comprehensive Water Project (JAMAB) in Iran. Considering the location of the meteorological stations of each valley, and taking into account the climatic conditions of each plain, representative stations for each valley were determined and water requirements of each valley were estimated and specified. Determinations were individually made for all annual crops and fruit trees of each plain, and for each case the following information was specified and saved in the computer program: area under cultivation, planting and harvesting date and stages of various growth period, [found using the facilities of different deputies of the Ministry of Jihad-e-Agriculture and results of the study of comprehensive project for development of agriculture]. With the change in the concept of reference plant in the Penman-Monteith method, the plant coefficient has been modified accordingly. For inclusion of a plant factor during various stages of growth, a special computer program was developed. This program provides the curves for changes in plant coefficient factor during the growth period and its value for each day of growth. By drawing the modified curves, it makes available the necessary means for determining the required index during the growth stage. For particular plants such as date palm, citrus, mango, and banana, ambiguities were cleared up by examining research results and scientific papers, and by inviting specialists to the consultation meeting. The total irrigation requirement is reduced by any amount of effective rainfall (Re) that is received.
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Water Conservation, Reuse, and Recycling: Proceedings of an Iranian-American Workshop Priorities for Allocation and Water Pricing for Optimum Use of Water As already noted, the major consumer of water (more than 93 percent) in Iran is the agriculture sector. The average water productivity of agriculture (crops and orchards) is 0.7 kg per cubic meter. Increase in the economic value of water is one of the major objectives in the Economic Development Programs of Iran. Increase in the economic value of water will be possible when the yield or return per specific volume of water increases. For this reason it is preferable to use the available water supply for producing commodities with higher economical efficiency, or to use it in regions where it returns more economic value. Based on the above discussions, determination of cropping pattern for each region, determination of crop water requirements, and finally volumetric allocation of water have been considered to be the important objectives for increasing the economic value of water. For optimum use of water allocated to the farmers, the following policies are considered: Control of water resources and volumetric allocation of water to the farms is based on crop water requirements and recommended irrigation efficiencies. Based on current law (established in 1983) price for regulated surface water is between 1-3 percent of the value of the cultivated crops. Based on the 1983 law, water pumping from groundwater resources must be in accordance with the crop water requirement and proposed cropping pattern in each region. In this case, price for groundwater resources is 0.25-1.0 percent of the commercial value of crop yield. Subsidies for water charges and supervision charges will be levied on farmers whose yields are higher than average. Water allocation will be terminated to the farmers who in two successive years consumed water at more than the permissible level. Policies will encourage the farmers to use less water and maintain their production at reasonable levels using proper management practices. Cropping Pattern and Water Requirements for Different Regions The cropping pattern in each soil and water resources development program is determined by considering factors such as climate, quantity and quality of soil water resources, social needs, livestock, food processing industries, government policy, farming culture of the region, job creation, marketing, transport, vertical and horizontal development of agricultural lands, crop rotation, mechanization, crop diseases, agricultural commodities, potential of executive organizations, health, environment, and sustainable development. For setting this policy in each region the following programs are considered: Investment for rehabilitation of present irrigation networks. Control and prevention of over-extraction of water resources.
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Water Conservation, Reuse, and Recycling: Proceedings of an Iranian-American Workshop Education as the basis for improvement of the methods. Efforts should be focused on education and extension to farmers for optimum use of water and increase in water productivity considering soil fertility, sustainable agriculture, and other environmental challenges. APPROACHES The challenges and opportunities for improving water productivity in the future are summarized in three system components as follows: biological (crop), environmental, and management. However, it is well known that water productivity is the interaction and consequence of all foregoing components in any irrigation system. In the biological realm, drought resistant varieties of crops play an important role in improving water productivity. In this case, genetic improvement of the irrigated crops has been a part of the effort. Specific breeding programs have also been aimed at improving water productivity in irrigated and dryland agricultural systems, using both conventional breeding and genetic engineering. A primary issue in this regard is the study of the interactions between soil fertility, plant nutrition, and water management at the level of plant, plot, and system, and all the way up to the basin level. Although parts of the objectives discussed above have been achieved, there are big gaps between the results obtained from research and the practical application of these results by the users. This is primarily because there has been little interaction between scientists, extension agents, and farmers for practical application of the latest findings. Although little is known about the factors causing the existing gaps, they are common in agricultural water management. The assumption is that new technologies have been picked up spontaneously and used in incorrect ways with insufficient attention by farmers. There are many aspects involved in how farming communities integrate biophysical and socioeconomic issues to adapt their agricultural systems to optimize water use efficiency and water productivity. Many important issues involving anthropology and socioeconomic sociology should also be investigated. Specifically in water institutions study agendas the following concepts should be addressed: Innovative institutions that would deal effectively with problems such as groundwater and waste water management. Rules of prices and regulations for improving water management.
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Water Conservation, Reuse, and Recycling: Proceedings of an Iranian-American Workshop New methods for enhancing stakeholder participation in institutions and in defining water policies and water management. Technical approaches for strengthening irrigation projects, such as equipping and renovating lands and irrigation networks (both in traditional and newly developed projects), and expansion of appropriate pressurized systems. Agricultural approaches such as selection and operation of appropriate crop patterns in different regions. In addition to the above-mentioned measures, the following technical approaches, management approaches, organizational approaches, and agricultural (biological) approaches are being performed for strengthening the laws that have been instituted by the government. Technical Approaches Equipping and renovating lands, including land leveling, land consolidation, and drainage and land reclamation. Constructing new irrigation networks and lining traditional irrigation networks. Expanding pressurized irrigation systems, including enforcement of sprinkler irrigation systems for uniform application of water, enforcement of low energy precise application (LEPA) irrigation for decreasing evaporation and preventing wind effects, and enforcement of micro-irrigation (surface and subsurface) to decrease evaporation effects. Management Approaches Making recommendations concerning irrigation programming. Enforcing water distribution systems using gated pipe in the field to improve conveyance efficiency and reduce deep percolation and evaporation. Supplying water requirements of the crops during critical growth stages. Reusing surface runoff and drainage water. Making use of marginal water. Organizational Approaches Establishing a water utilization organization. Providing government subsidies for pressurized irrigation systems and other infrastructure. Extending applied research, and improving education and extension programs. Improving and applying suitable pressurized irrigation system technologies.
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Water Conservation, Reuse, and Recycling: Proceedings of an Iranian-American Workshop Agricultural (Biological) Approaches Selecting drought resistant crop varieties. Selecting appropriate crops. Optimizing use of other agricultural inputs, such as fertilizers, herbicides, and other supplements. Implementing a proper crop rotation program. SELECTED BIBLIOGRAPHY Allen, R., G.M. Smith, W.O. Pruitt, and L.S. Pereira. 1966. Modifications to the FAO crop coefficient approach. Proceedings of the ASAE International Conference on Evapotranspiration and Irrigation Scheduling, Nov. 3-6 San Antonio; TX. Blaney, H.F. and W.D. Criddle. 1950. USDA Soil Conservation Service Tech. Paper No. 96, p. 48. Doorenbos, J. and A.H. Kassam. 1979. Yield response to water. FAO Irrigation Drainage Paper 33, United Nations, Rome. Doorenbos, J. and W.O. Pruitt. 1977. Guidelines for predicting crop water requirements. Irrigation and Drainage Paper 24, Rev., Rome. p.156. Dehghani, S.H, A. Alizadeh, and A. Keshavarz. 1999. Implementation of water use pattern in terms of volumetric supply of water to farmers, IAERI. Monteith, J.L. 1965. Evaporation and environment. Symp. Soc. Exp. Biol. 19, p. 205-234. Ministry of Agriculture and Meteorological Organization. 1998. National documents of water; Crop water requirements, Vol. 30. Penman, H.L. 1948. Natural evaporation from open water, bare soil and grass. Proc. Roy. Soc. A. 193:120-145. Smith, M., R. Allen, J.L. Monteith, L.A. Pereira, and A. Segeren. 1991. Report on the expert consultation for the revision of FAO methodologies for crop water requirements. FAO/AGL, Rome. Smith, M., R. Allen, and L. Pereira. 1996. Revised FAO metho1ogy for crop water requirements. Proceedings of the ASAE International Conference on Evapotranspiration and Irrigation Scheduling. Nov. 3-6, San Antonio, TX. Pp. 16-123. Thornthwaite, C.W. 1948. An approach towards a rational classification of climate. Geog. Rev. 38, p. 55-94.
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