More than 98% of inter-farm and on-farm canals in the Khorezm region were laid during the period of intensification of agricultural production in the open ground and do not have an anti-filtration coating. As a result, the efficiency of the canals is very low and a large amount of water is lost during transportation from the water source to the field due to filtration.

In 2009-2012. Employees of the Urgench State University (USU), with the support of the GEF SGP, tested the technology of isolating the bottom and edge of the canal with a polyethylene film to reduce infiltration processes in a single WUA. The channel "Navruz-yap", which is located on the territory of the Yangiarik district of the Khorezm region, with a length of 2.6 km, was selected for work.

Pumping water out by pump

Before anti-filtration measures, the canal provided water for 400 hectares of irrigated land and supplied more than 2,500 people living in the adjacent territory with irrigation water. The throughput of the canal was 1.5 - 2 m3 / s, but due to filtration, the water did not reach the fields in sufficient quantities, which led to a constant shortage of irrigation water. The efficiency coefficient of the Navruz-Yap canal varied seasonally by months from 0.43 to 0.52, and averaged 0.49 during the growing season. In other words, 51% of the irrigation water in the canal was uselessly wasted for filtration and fed the groundwater.

Excavation work - channel preparation

As part of the project, cleaning and filling works with an excavator, as well as manual preparation of the edge and bottom of the canal, were carried out on the Navruz-Yap canal. In this case, the slope angle of the canal, the bottom and slopes of the canal were prepared in such a way as to ensure the gravity flow of water to the irrigated fields. Next, a 10-15 cm sandy layer was laid for laying a polyethylene film, 100 microns thick. On top of the film, a 10-15 cm sand layer was poured onto the bottom and edge of the channel to avoid damage to the film (Fig. 1 and 2). And finally, on top of the sand, soil was laid up to 1 m thick at the bottom of the channel, and 0.5-0.6 m at the edges of the channel.

Start to lay the film подпись к фото

Litter of the film on the prepared channel bottom Backfilling of sand and soil on top of the film

The measures taken to isolate the bottom of the canal gave impressive results. Average efficiency increased to 0.89. We managed to save a lot of water and use it for irrigation of additional hectares, which means getting more harvest and more profit. The numbers are shown below in economic calculations.

Specialists of the NGO "KRASS" conducted an analysis of the economic efficiency of the measures taken. Within the framework of the project, the costs, payback period, as well as direct and indirect benefits from anti-filtration measures were calculated. For convenience, the calculations were carried out for 1 km of the channel length with the perimeter of the bottom and sides equal to 5 meters.

The total cost of insulating 1 km of the canal bottom with a plastic coating amounted to 32.2 million soums (see the Table). As a result of the implementation of this anti-filtration measure and the increase in the efficiency of the canal, about 4 million m3 of water was saved during the year (calculations per 1 km of the canal). Taking into account the price for delivery of 1m3 of irrigation water equal to 5 soums, the cost of delivery of irrigation water decreased by 20.1 million soums. After the appearance of additional hydraulic structures, water now flows by gravity, which makes it possible to abandon a large number of pumps that consume a large amount of energy. As a result, electricity costs decreased by 9.4 million soums.

The measures taken made it possible to provide the fields with irrigation water in a timely manner and in sufficient volume, as well as to increase the yield in the first year by 1.5 centners per hectare, and in subsequent years by 2-3 centners. The calculations for additional harvest income were based on cotton, which is considered the main crop in the region. The profitability of raw cotton grown in the fields adjacent to the canal is 15% and the additional harvest will be 71.5 tons (from 476.3 hectares). With an average price of 1 ton of raw cotton 700 thousand soums, the total income from the additional harvest will amount to 7.5 million soums (calculated per 1 km of the canal). Given the increase in yields in the coming years, it can be assumed that income will gradually increase.

Economic efficiency of insulating the canal bottom with plastic wrap, per 1 km of canal length with a canal perimeter of 5 meters

* - price for 1 kW of electricity = 104.4 soums (2012)

The economic efficiency of the project can be considered according to 2 scenarios, that is, at the level of farms, as well as at the level of WUAs and farms. When calculating according to the 1st scenario, the costs of delivery of irrigation water to the field are not taken into account, since farms pay a contribution to the WUA based on the volume of irrigated area, regardless of the volume of water received. At the same time, the total benefits after the implementation of anti-filtration measures will amount to 16.9 million soums (Table), which will fully recoup the costs within 2 years, and in subsequent years will already receive additional profit. According to the second scenario, at the WUA level, when calculating the benefits, the savings in the delivery of irrigation water to the fields of farms are additionally taken into account. At the same time, the annual total benefits from the use of this technology will amount to 37 million soums, which will fully recoup the costs in the first year.

In conclusion, we can say that the project to isolate the bottom of the canal with a plastic film within the framework of anti-filtration measures justifies itself both from an environmental and economic point of view. As you know, for the implementation of any project, first of all, its economic efficiency is important, i.e. its recoupment, otherwise the project will be recognized as inexpedient. But, do not forget that, in this case, we are talking about water, about water resources. Water is life. Water is the fate of many people living in this area. And therefore it is necessary to implement any measures to save water.

R. A. Eshchanov, H. Zhabbarov, J. Nurmetov
Urgench State University
I. Rudenko, K. Nurmetov
NGO "KRASS"

Contacts:

Prof. R.A.Eshchanov, Doctor of Biological Sciences, Rector of UrDU, (998 62) 226 61 66, ruzimboy@mail.ru
H. Zhabbarov, Ph.D., Associate Professor, UrDU (998 90) 126 13 49, jxujyaz@mail.ru
Zh.Nurmetov, Researcher, UrDU, (998 91) 917 37 67,