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<Forum on the Caspian, Aral and Dead
Seas-Perspective Water Resources Development Problems and Features in the Aral Sea Basin Hikaru Tsutsui and Nobumasa Hatcho Problems associated with water resources in the Aral Sea basin have been analyzed. Demand based calculation of water needs can be a first step to find viable and feasible solutions to the water resources and associated environmental problems in the Aral Sea Basin area. In addition, new initiatives to conserve the environment by creating shallow water bodies in the dried sea bottom of the Aral Sea have been described and their implications discussed. 1. Introduction The Aral Sea used to be the world's fourth largest inland lake and is located in the arid region of Central Asia. Its area covered approximately 68,000km2 and the maximum depth was 67m. Water runs into the lake through two major rivers, Amudarya and Syrdarya of which the water sources are located at the Tien Shan and the Pamir. Until the 1950s the water level was comparatively stable due to the total quantity of water inflow from the Amudarya and Sirdarya rivers (about 110 km3/year), precipitation and groundwater were nearly equivalent to evaporation loss from the lake surface. The level of water, however, has drastically dropped over the last 30 years due to water and land resources development that started after World War II (see figure 1). River water has been the source of vastly expanded irrigation withdrawals over the past three decades - the amount of irrigated land has increased by a factor of 1.5 in Uzbekistan and Tadshikstan, 1.7 in Kazakhstan, and 2.4 in Turkmenistan since the 1960s, and the annual river inflows from Amudarya and Syrdarya to the Aral Sea, once 50 billion m3 per year, dropped to only 5 billion m3 in the 1980s and has become a mere a trickle today. The total irrigated area in the basin is now estimated at 7.6 million ha. Reclamation of 7.6 million hectares of irrigated farm land caused environmental degradation in and around the Aral Basin. While the Aral Sea has recessed by about 60 percent from its size in the 1950s and its salinity has risen from 1percent to 2.7 percent, the yield of fishery that used to be over 40,000 tons/year has gone down to zero. Aral's recession has also destroyed river and sea transport as well as the ship building industry. The drop in the water level of the Aral Sea has caused other diversified and complicated environmental problems. As the level of groundwater reduced, many large and small wetlands and lakes around the Aral Sea have dried up or have been salinized. Salts accumulated on the surface of the lake bottom are now blown about with sand and dust and damage human health and farm lands in the surrounding towns such as Aralsk and Muynak. The residents in the area have a serious problem with the drinking water supply due to the decrease of groundwater resources. Extinction of fauna and flora species in wetlands is to be seriously considered, too. Many studies by Russian scientists, international organizations (UNEP and WB) and international/national researchers have been carried out to rehabilitate the Aral Sea and to conserve the degraded environments as well as to develop the region. Of these studies, the most important is the one on water resources which has a direct impact on the Aral Sea itself, agricultural development and environments. Previous studies have mainly focused on water availability and supply of Amudarya and Sirdarya rivers without paying much attention to how the water is used locally. It would be important now to shift the focus from the supply side to the demand side when Colchozes and Sowchoses, which played important roles in managing water locally, are being disintegrated. Without establishing local specific measures of managing water effectively, any proposals for saving water to avoid further deterioration of water supply conditions and environments will not be feasible. As a first step, water demands of lower Amudarya delta are simulated. The model is a robust one with many unknown parameters and assumptions, however, it can be a start for initiating the analyses on water demands. In addition, by establishing this kind of water model, the variations in parameters can easily be reflected in the calculation of water demands which contributes to establishing a better balance between water demands and supply as well as to initiating better water management practices. In addition, a newly proposed project for conserving environment by constructing dike systems in the Amudarya delta area is briefly described and discussed for its possible future implications.
2. Agriculture and Irrigation Requirements 2.1 Cotton problem In discussing the prospects for the development of the Aral region, more detailed attention must be paid to the consequences of heavy reliance upon cotton cultivation. The need for and increase in cotton production was considered to be one of the most important reasons for a new, extensive development of irrigation in Central Asia. It was assumed that such an increase would enable to clothe the population of the country and to increase exports of cotton and cotton fabrics. As a result of the expansion of irrigation, the cotton production in central Asia and Kazakhstan almost doubled between 1960 and the 1975-1980 period (although it subsequently began to decrease). Still, the question arises: is it necessary for the country to produce this much of cotton, or can less be produced without a loss to the national economy? Any viable solution must address the water use for cotton production, since this crop consumes nearly 50 percent of total irrigation needs in the region. Irrigation application for cotton in the region varies from 7,500 to 10,100 m3/ha per crop season, averaging 8,700 m3/ha. Reducing water use for cotton will not be straightforward. The former Soviet Union was the world's largest cotton producer, and over 90 percent of its fiber was produced in the Aral region. For many years the cotton complex of Central Asia was a "success story" of Soviet agriculture, and to the Central Asia republics, cotton is central to their economic life. A transition away from cotton, requires the emergence of an alternative economic activity. We can think of generating employment in a greatly expanded cotton textile industry as a substitute for primary cotton production. In this sense, the preservation of the Aral Sea and the remedy of the regional crisis are linked with the successful adoption of a new economic development strategy. 2.2 Land Use/ Cropping Patterns Low-productivity saline soils on which currently low yields are obtained despite an enormous water use, must be removed from irrigation. Even if only 5% of the lands which are least suited for irrigation, that is 0.5 million hectares, are removed from irrigation (given a current existing water consumption on these lands of 15,000 m3/year), water saving would amount to some 7 km3/year. It is possible that because of environmental and economic concerns it will be desirable to remove an even larger area from irrigation, because 15% of the irrigated lands in the Aral basin presently are in an extremely unsatisfactory condition. This would accordingly yield an greater savings of water: about 15-20 km3/year or more. It should be emphasized that the removal of lands from irrigation must be preceded by the resolution of social problems of the population related to this irrigation: creation of new jobs and, consequently, occupational retraining, relocation of population and enterprises for losses associated with the cessation of irrigation, and reorientation of the economy. Without this the removal of lands from irrigation will be attended with great hardship. It is also necessary to provide for reclamation of lands when irrigation is stopped. A study must also be made on the possibility of reducing the area under rice cultivation. Rice is the crop requiring the most water and under the conditions prevailing in Central Asia and Kazakhstan its irrigation consumes 25,000-55,000m3 of water per hectare per year. A reduction of the areas planted with rice in the region by at least 100,000 hectares would make it possible to liberate at least 3 km3 of water annually. It must be noted that the greater part of such large amounts of water is used to leach salts that accumulated in the soil during the non-rice crop cultivation period. Water requirements for paddy rice cultivation should be considered taking into account the impact of the leaching function of irrigation water. It is entirely evident that the intensive expansion of irrigated land must be replaced by the more intensive use of existing irrigated lands through improved irrigation water management, crop rotations, technologies, and the structure of sown crops. An important role in the intensification of agricultural production on irrigated lands should also be played by the development of new varieties. 2.3 Calculation of ETo and Net Irrigation Needs Reference evapotranspiration (ETo) of the lower Amudarya delta was calculated by the Penman-Montieth method with the climatic data of Chimbay which is located in N: 45/57' and E:59/ 49' and EL=66 m (see figure 1). Wind data at Chimbay were not available and thus values of Mazari-Sharif in Afghanistan were used. The calculated results from April to October (vegetation period) are shown in table 1. Table 1. ETo in the Lower Amudarya Delta (Chimbay Station)
Major crops grown in lower Amudarya delta area (KKAR:Kara-kalpakstan Autonomous Region) are cotton, rice, fodder and maize. FAO standard crop coefficients in dry regions and growing periods for different growth stages are utilized to calculate crop water requirements for different planting periods. Net irrigation needs (m3/ha) of each major crops are calculated on a decade basis and are shown in figure 2. Calculated values, values of Dr. Zhu and other sources are shown in table 2. Table 2. Comparison of Net Irrigation Needs (m3/ha)
1) Field Application Efficiency of 90 % assumed.
The calculated results show similar values as other information sources except for rice which is calculated relatively low. The reason could be attributed to a relatively small deep percolation rate assumed, or due to the crop coefficient used for rice. In addition, leveling accuracy could also affect the irrigation needs of rice. According to the Kazakh Research Institute of Water Economy, the increase in irrigation needs of rice could reach to 14,000 m3/ha between the field with the leveling accuracy of +/- 3 cm and the one with +/- 15 cm. (table 3) Table 3. Land Leveling Accuracy and Water demand of Rice
Kazakh Research Institute of Water Economy,1991(JALDA report 1993) In addition to climate and crop data, such factors as the water supply from underground, the differences in irrigation methods, and leaching requirements which affect irrigation needs would require further field studies for establishing a better water management model based on crop water demands. 3. Simulation of Water Demands in KKAR To test the viability of a demand based approach as mentioned above, water demands in KKAR with an irrigated area of 558,600 ha was simulated using the cropping pattern of 1987. In this simulation, planting started from the second decade of April while the harvest was done in October. The peak demand period came in July with a peak of 1,090 m3/sec in the second decade (case I). When the areas of cotton and rice were reduced as much as 30 percent and the area of maize was increased to 33 percent (case II), the peak demand was reduced to 1,018 m3/sec and 1.6 km3 of seasonal water demands could be saved. Similar savings and peak cuts could be done by improving the irrigation efficiency from the original 50 to 60 percent (case III) with a saving of 1.8 km3 of total demand and a peak cut to 908 m3/sec in July. The comparison of water demands of three cases simulated is shown in figure 3.
By establishing a simple simulation model, it is easy to change parameters of irrigation and to check the impact on water demands. The model can be applied to identify in which area efforts should be directed to save water and to better match between water demands and supply. 4. Environmental Conservation by Creating New Water Bodies New initiatives to create artificial reservoirs (water bodies) in the dried bottom of the Aral Sea were started in 1987 to conserve environments and to rehabilitate local production bases such as fishing, mink culture, and irrigated agriculture.* Artificial reservoirs were created by the construction of dikes along the contour lines with an average water depth of 0.9-2.5m (see figure 4). The dimensions of artificial reservoirs are listed in the table 4 below. Table 4. Dimensions of Artificial Reservoirs (constructed/planned)
In addition, lakes Sudochie (area 61,500 ha with 922 mil. m3) and Makpalkul (15,300 ha with 230 mil. m3) are rehabilitated to allow water level control for fish breeding. Natural lakes and ponds are supplied with river/drainage discharge. Creation of these reservoirs and water bodies has swiftly brought about benefits to the region. Fish catch, which once had been more than 20,000 ton in the southern part of the Aral Sea in the early 1960s and had become zero in the early 1980s, has recovered to 4,670 ton in 1993. Mink production reached back to 10,000 in 1994 and a newly irrigated area of 31,000 ha has been developed. With the return of agriculture/fish production, the population of Muynak, which was 20,000 in 1960 and declined to less than 10,000 in 1987, has grown to about 13,000 in 1994. In addition, it is reported that the incidence of dust storms has been declined. Future plan includes total development of 267,000 ha of water bodies. Several problems have to be solved to realize full developments of these water bodies. First is the stable supply of water from Amudarya. The total expected discharge required for compensating evaporation and water uses are estimated to be 4.5 km3. Inflow of water from Amudarya to the Aral Sea in recent years, is below 5 km3 except for 1987 and 1992. The water intake into these water bodies will result in the total death of the Aral Sea.
Furthermore, low water supplies for several years will result in the drying up of these water bodies and shallow water bodies are not efficient means of storing water because of la arger water surface area that results in more evaporation. The Silt load of Amudarya river is very high, and with 40 million tons/year the sedimentation in these water bodies will reduce their capacity and their functioning. To avoid the sedimentation of created water bodies, discharge sluice with a capacity of 500 m3/sec is planned to be constructed at the low end of Mezhdureche where the water of Amudarya is initially fed. Impacts of creating these water bodies, especially on the water balance (inflow and evaporation rate) and sedimentation, need further investigation before completely implementing the development plans. 5. Conclusion Problems associated with water resources in the Aral Sea basin have been discussed. Demand based calculation of water needs can be an important initiative to find viable and feasible solutions to the water resources and the associated environmental problems in the Aral Sea Basin area. In addition, new approaches to conserve the environment by creating shallow water bodies in the dried sea bottom could become a viable option if careful attention is paid to the available supply and sedimentation problems.
P. Raskin, D. Stavisky, E. Hansen and Z. Zhu (1992). Simulation of Water Supply and Demand in the Aral Sea Region. Water International, 17. pp. 55-67. H. Tsutsui (1992). Irrigation and Envrionment - Aral Sea Basin in Central Asia. Journal of Irrigation Engineering and Rural Planning. JSIDRE. P. P. Micklin (1991). The Water Management Crisis in Soviet Central Asia. The Carl Beck Papers in Russian and East European Studies. No. 905. Univ. of Pittsburgh Center for Russian and East European Studies. Z. Zhu (1991). Water Development Strategies for teh Aral Sea Region. 7th World Congress on Water Resources. Morocco, May, 1991. I. S. Zonn (1992). The Problem of the Aral Sea in the Light of New Geopolitical Policy. The Second International Planning Meeting of the GIF. May, 1992. Istanbul. FAO (1992). Application of Climatic Data for Effective Irrigation Planning and Management: Training Manual ---------------
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