Solutions for the rational use of water in the conditions of the Republic of Uzbekistan

The article studies data on the use of water in the territory under consideration and, on their basis, suggests ways of their rational use. Recommendations are given for the rational use of water, these are mainly measures to increase the efficiency of the on-farm network, improve the technique and technology of furrow irrigation, and introduce advanced systems of equipment and technology for irrigation.


Introduction
At present, as in the future, the main limiting factor to improve the production of agriculture further in this large region of the lower reaches of the Amu Darya is the limited free flow of the Amu Darya water. It should also be noted that the suspension of the development of new lands in the Amu Darya basin as a whole, including the Republic of Karakalpakstan, which has taken place in recent years, cannot persist in the future, since population growth and, accordingly, the need to provide food as well as the need for growth the economy of the republic requires a slight increase in the rate of development of irrigated lands through the reconstruction of old irrigated lands. On the other hand, it is also known that the water resources of the river basin are exhausted and distributed over the republics, i.e. limits are set for individual regions.
Therefore, at the same time, by reducing the value of specific water consumption, it is necessary to carry out a number of measures for water conservation and to gradually achieve their introduction into production.

Materials and methods
The study uses a method that allows the loss of water from the on-farm network and allows you to determine the flow rate using the following method: Where: Ʃ is total water losses in the investigated section of the canal; Q b -Q H is water flow in the upper and lower sections; Q b , is water flow through all outlets in the canal section.; Q sbr is water discharge discharged in the investigated area.

Results and Discussion
Taking into account the peculiarities of the natural and climatic conditions of the Republic of Karakalpakstan, at the same time, by reducing the value of specific water consumption, it is necessary to carry out a number of comprehensive measures for the economical use of water supplies, namely:  Conduct planning (capital and operational).  Increasing the efficiency (efficiency) of the channels.  Improving the technique and technology of furrow irrigation.  Introduction of perfect systems of irrigation technology (drip irrigation, etc.).
Saving water by leveling fields. It is known that most of the areas of the Republic of Karakalpakstan are old-irrigated with a primitive irrigation and reclamation system. These lands are characterized by the lack of planning of irrigated areas. So in some areas, the difference in the marks of one field reaches up to 30 -40 cm (within 3 -4 hectares), which requires the supply of a huge amount of water.
Long-term studies carried out on the territory of the Republic of Karakalpakstan show that if the difference in marks on one check (4 ha) is ± 35 cm, then due to this there is an overconsumption of water of the order of 1420 m 3 / ha. Almost the same losses are estimated for the non-vegetation period, so during the period of land leaching, the overconsumption of water with a difference of ± 30 cm (for moderately saline lands) reaches 2100 m 3 / ha.
A set of measures to ensure water saving by increasing the efficiency (efficiency) of irrigation canals.
The results of many years of research carried out in the Khorezm region and the Republic of Karakalpakstan show that the efficiency of the main part and individual inter-farm canals (where they pass through heavy soils) is quite high and ranges from 0.88 to 0.96. On-farm canals have the lowest efficiency, the average value of which corresponds to 0.65.
Analyzing the current state of the main and inter-farm canals, it can be noted that their technical condition is in a relatively satisfactory condition, and taking this into account in the coming years, there is no need to invest large capital costs on these canals for concreting canals (with the exception of sandy areas) and other types of expensive measures.
It should be specially noted that, according to the data of numerous studies, on-farm channels have the lowest efficiency. Therefore, the primary measure to increase the efficiency of canals should be aimed at the complete reconstruction of on-farm canals.
The main results of studies on water losses in on-farm canals, which are on the balance of farmers, as well as the expected water savings in the case of engineering measures, are given in table. 2.
As can be seen from the data in the table. 2, at the first stage, it is possible to increase the efficiency from 0.65 to 0.73 only by arranging a trough network on group irrigation ditches and on other links by carrying out reconstruction on earthen channels. The only way to achieve a water saving of 220 m 3 / ha is to increase the efficiency of on-farm canals (in the cotton-growing zone) Saving water through improved technology.
Features of the local conditions of the Republic of Karakalpakstan, the following irrigation technologies which were tested on experimental plots can be recommended.
 Ordinary traditional watering, which is practiced on farms (watering from one side).  Irrigation through the furrow.  Backwatering, water supply from both sides of the furrow, by cutting single-breasted temporary sprinklers.
The main disadvantages of the ordinary irrigation used in the production, which ultimately leads to excessive consumption of irrigation water, are high labor expenses, long duration of irrigation, a large volume of vertical filtration.
Furrow irrigation is successfully applied on heavy soils, and this method of irrigation improves soil aeration.
The last option, counter irrigation with concentrated water supply. With this option, watering is carried out from both sides through single-breasted temporary sprinklers. Water supply is carried out simultaneously, while the furrow length and irrigation time are reduced by 1.5 -2.0 times. A condition for this is a good leveling and zero slope. According to the data of field observations of the experiments carried out using this technology, the following results were obtained. Saving water through the introduction of perfect irrigation systems. One of the most effective approaches for the rational use of water for irrigation is the use of drip irrigation, which is widely used in world experience, especially where there is a deep shortage of water.
Conducted in 2020 -2021 In various zones of the Republic of Karakalpakstan, experiments on the use of drip irrigation systems for irrigating tomatoes, cotton plants, orchards have shown that, subject to technical and operational requirements, this technology gives a high economy of water resources (table 4).
Along with the great advantages of drip irrigation, there are a number of disadvantages, such as the relatively high cost of construction in modern conditions of the transition of farms to market relations. This is the main deterrent to the introduction of this irrigation system in general in Uzbekistan and in particular in the Republic of Karakalpakstan.

Conclusion
It is known that the problem of water conservation and economical use of water includes the implementation of a set of organizational, agro technical and technical measures. Along with this, the above measures are currently a priority from the point of view of economical use of water resources for the conditions of the Republic of Karakalpakstan. Table 5 summarizes the data on saving water resources in the implementation of the above measures.