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Tukhtaeva Khabiba Toshevna, Head of the Department, Ph. D., Bukhara Branch of the Tashkent Institute of Irrigation and Agricultural Mechanization Engineers
E-mail: Habiba1078@mail.ru Juraev Sharafiddin Babakulovich, Second year student at the Bukhara branch of the Tashkent Institute of Irrigation and Agricultural Mechanization Engineers Rakhimova Diyora Kakhramon kizi, Second year student at the Bukhara branch of the Tashkent Institute of Irrigation and Agricultural Mechanization Engineers
Yusupov Hamid Hasan ugli, Second year student at the Bukhara branch of the Tashkent Institute of Irrigation and Agricultural Mechanization Engineers
STUDY OF LOCAL IRRIGATION SYSTEMS AND SELECTION OF THE MOST APPROPRIATE FEATURES FOR THE EFFICIENT USE OF WATER AND LAND RESOURCES
Abstract: The article analyses efficient water management methods and prospects for irrigation systems improvement for the region. Scientific and practical proposals and recommendations for the creation of local irrigation systems based on the use of local water resources for desertification control are given.
Keywords: desertification, water and land resources, atmospheric precipitation, runoff, local irrigation, yield.
Introduction. The subject of research is the des- conditions for the annual formation of temporary ert rangeland of the Central Kyzylkum - an extra-arid surface runoff over the seasons with their quantitaregion with annual precipitation of90-180 mm and tive assessment.
annual evaporability of 1400-1600 mm. Due to its For a good understanding of the situation, assess-high agro-climatic potential it is possible to cultivate ments of water resources that are formed in desert heat-loving crops, and with sufficient moisture the rangelands and, for the most part, do not participate rangelands of the region can reach high productivity. in run-off of the river systems were carried out.
Firstly, reliable information on all types of wa- As a rule, desert regions have potential sources of ter resources is collected for the area under consid- water of different quality: groundwater, wastewater, eration, including groundwater, discharge water, precipitation moisture. In addition, the dryland des-wastewater and temporary surface runoff. Plastic ert zones have significant reserves of valuable minrelief mapping method and water balance of the ter- eral and other resources that can be used in fertile ritories were used to assess the temporary surface lands for the development of local irrigation arrays. runoff. On the basis of this, regionalization of the Water supply problem of the region can be Central Kyzylkum was carried out according to the solved by development of the areas rich in natural
resources, increasing rangeland productivity, and desertification control.
Our observations and calculations of watershed have shown, there is water in the desert, but it returns to the atmosphere very quickly and is lost due to seepage.
Therefore, these major issues of desert regions require technical intervention.
Aims and objectives. The aim of the research is the scientific development of proposals for the rational use oflocal water resources for desertification control in the Central Kyzylkum region.
Main body. The article describes developed methods for determining the size of the watershed areas of the drainage basin, the redistribution of the runoff within them, methods for the conservation and rational use of accumulated moisture, and assess temporary surface runoff resources in the macro-, meso- and micro- watersheds.
A survey of suitable for irrigation of land in Ko-nimex area based on the use of local waters was performed. Plots were determined, conditions for the accumulation and preservation of precipitation moisture were studied; and field experiments were carried out on those plots. Research was carried out on forage crops. Alfalfa seeds sown in experimental plot in April with the standard of12-15 kg/ha, with seeding depth of 3-5 cm, satisfactory seedlings were obtained (according to the previously washed soil the norm of 1.5-2 thousand/ m3 ha). With many years of alfalfa sowing, the yield of feed per hectare of irrigated soil is about 100 metric quintals/ha. 0.868 l/sec of water is needed to obtain this yield [1].
The productivity of plant life in the desert is directly dependent on the amount of atmospheric moisture and its seasonal distribution. Under optimal temperature conditions, moisture causes the most important biochemical and physiological processes to occur. With sufficient reserves of moisture in the soil, the plants grow to their full potential, and with a lack of it - go into a low-active state, all their functions slow down. The direct reaction of desert
plants to a lack of moisture is the partial loss of their leaves and shoots and, consequently, a reduction in water consumption.
Knowledge of the water regime of desert plant life is a reliable basis for selection of the most drought-resistant forage plants to improve desert rangelands.
In increasing the desert forage reserve, further irrigation and development of new massifs is of great importance. Of the 30 million hectares available in Uzbekistan, only about 12 million hectares of desert and semi-desert rangelands are used.
Development of water supply for all rangelands (excluding Ustyurt) will provide year-round forage for 9.1 million sheep as a result of improved livestock numbers on rangelands and the actual increase in feeding rates, which naturally will have a positive effect on the productivity of pastoral industry.
The yield of desert rangelands ranges from 2 to 5-6 metric quintals/ha, decreasing in some unfavourable years to 0.5-1 metric quintals/ha of forage. Research by the Institute of Botany has shown that sowing semi-shrub and shrub plants with the use of appropriate agricultural techniques can improve the productivity of rangelands of clay desert by 2-3 times. For example, by the end of the first year of the growing season, the yield of plants reaches 2-3 metric quintals/ha, by the end of the second year - 5-7 metric quintals/ha, and in the third and subsequent years - 8-12 metric quintals/ ha of air-dry weight.
The calculations found that the biological potential of cultivated plants in Uzbekistan is very high. So biologically potential yield ofbasic grains, calculated by the measurement of solar radiation, is 352-412 metric quintals/ha, legumes (soybeans) - more than 300 metric quintals/ hectares, potatoes - 2290 metric quintals/ha, sugar beets - 4100 metric quintals/ ha, cotton - 265 metric quintals/ha. Biologically potential yield of cultivated plants is calculated on the average photosynthesis efficiency of 8% (Photosynthesis and bio-based products, the average for the growing season photosynthetic active radiation
in Uzbekistan is 210 kJ/cm2, the average caloric content of dry plant mass is 19 kJ/g).
The quantitative correlations of the rangeland vegetation yield with environmental factors are es-
The data shows increase of the rangeland vegetation yield with increasing precipitation, while the water-use ratio decreases. It is important to note the fact that the water-use ratio of rangeland vegetation (391-500 m3/metric quintal) is significantly less than the water-use ratio of cotton when cultivated under rain-fed conditions (450-630 m3/metric quintal). This indicates that the biological potential of rangeland vegetation in relation to the water factor is greater than cotton. However, this statement requires additional analysis.
The yields of forage crops, when treated with mineral fertilizers, increases by 1.5-2.5 times in comparison with those indicated in the Table 1.
The long-term average resources of temporary surface runoff from watersheds in the lowland and foothill zones of Uzbekistan (local water resources) amount to 704 million m3 per year [2]. Without significant reduction of regular river flow, soil and groundwater, these water resources can be used to
tablished. For example, the average yield (air-dry weight) of the crop coverage of natural rangelands depending on precipitation over October-May can be determined from the (Table 1).
increase the biological productivity of desert regions in four main areas:
1) creation of regular perennial irrigation systems. With an average irrigation rate of 12 thousand m3/ ha per year (gross), the resources of temporary surface runoff (determined in this article) will allow the development of 58.8 thousand hectares of new land;
2) creation of inundation irrigation systems and other methods of accumulation, storage and economic use of local water resources for the cultivation of food grains and forage crops. With an average irrigation rate of 9.0 thousand m3/ha per year (gross), 78.2 thousand hectares of new land can be developed;
3) creation of inundation irrigation systems for the cultivation of food grains, orchards and vineyards. With an average irrigation rate of 7 thousand m3/ha per year (gross), 100 thousand hectares of new lands can be developed on the basis of local surface runoff;
Table 1.- The dependence of the yield of rangeland vegetation on the amount of precipitation in October-May
Precipitation in October-May, mm Yield of rangeland vegetation, metric quintals/ha Water-use ratio, m3/metric quintal
1 2 3
50 1.0 500
100 2.0 500
150 3.0 500
200 4.0 500
1 2 3
250 5.0 500
300 6.2 484
350 7.8 449
400 9.7 412
450 11.5 391
500 12.75 392
550 14.0 393
4) creation of inundation irrigation systems for the Based on local conditions, these methods can be cultivation of cucurbitaceous food and fodder crops. applied individually or in combinations. Approxi-With an average irrigation rate of5 thousand m3/ha mate assessment indicates that their implementation year (gross), using the resources of the local surface will increase biological yield. runoff, 140 thousand hectares of new land can be developed.
References:
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2. Лешинский Г. Т. Ресурсы временного поверхностного стока пустынь Средней Азии и Западного Казахстана, - Ашхабад. Ылым, 1970.
3. Махмудов М. М. Теория и практика фитомелиорация пастбищ Кызылкум. // Проблемы пастбищного животноводства и экологии пустынь.- Самарканд, 2000.- С. 138-140.
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