Azizdzhan fazilovich babadjanov

Collector-drainage network. Simultaneously with the expansion of irrigated lands and the construction of an irrigation network on reclamation-unfavorable lands, a collector-drainage network was being built. (Appendix 4).
As of January 1, 2004, the length of the collector-drainage network (CDN) was 13939.26 km, including 2649.03 km - inter-farm, 4479.08 km - on-farm and 6811.17 - closed drainage networks. The specific length of CDS is 47.66 running m/ha. As of January 1, 2017, the amount of diverted collector and drainage water amounted to 1551.29 million m ³ , of which 550.35 million m ³ is discharged into the river.
The average annual discharge of collector-drainage waters varied during the period under review from 67.42 to 31.82 m ³ /s, increasing in high-water years and decreasing in low-water years. The mineralization of collector-drainage waters during the period under review decreased from 6.52 to 4.65 g/l (Fig. 2. 7 ).

Figure. 2.7 . _ Change in average annual discharge and salinity
collector and drainage water
Changes in the hydrodynamic and hydrochemical regimes of groundwater are considered for deposits identified in accordance with the geological and structural features of the territory.

§2.6. Technogenic factors contributing to the formation and development of the water management situation

Based on the results of desk studies of hydro-regime data, cartographic material was created, as well as edited and entered into the geodata bank. Comparing the results of studies in 2016 and 2018, it can be noted that the mineralization of groundwater slightly decreased in the absence of irrigation. The direction of the ground flow has changed. If in 2016 filtration from the canal towards the irrigated area was observed, then when irrigation was stopped and the drainage networks were emptied, its draining role was restored.

The achievement of critical depth by groundwater (less than 1.5 m) indicates insufficient natural drainage of the territory.
Many years of experience in the use of irrigated lands in the Kashkadarya region indicates that the development of negative soil processes associated with the depth of occurrence and the salt composition of groundwater, although it has been proven, is not so great as to speak of widespread deep soil changes under the influence of irrigation.
To compile maps, the method of interpolation of data from cameral and field studies was used, on the basis of which cartographic material was created, and the rest of the research results were entered into the data bank.
The hydrogeological and reclamation assessment of irrigated lands is based on the following indicators:
- depth of groundwater;
- the degree of natural drainage of the territory;
- mineralization and chemical composition.
In hydrogeological terms, the irrigation area is located within the Quaternary deposits. The first groundwater aquifer is confined to the Upper Quaternary modern subaerial deposits and the Lower - Middle Quaternary deposits) [3].
The aquifer is free-flowing, the water level is set at a depth of 2.87 to 10.8 m at absolute elevations of 345-377 m. Groundwater is fed mainly due to infiltration of precipitation. Waters occur in the form of a slow ground flow directed from the north, northeast to south and southwest to the valley of the river. Kashkadarya.
The achievement of critical depth by groundwater (less than 2.0 m) indicates insufficient natural drainage of the territory. Replenishment of groundwater (GW) reserves as a result of irrigation leads to a rise in their level. Starting from depths of 4-5 m, GW are spent on total evaporation, and this consumption is quite significant. So, when the depth of GW occurrence changes from 5 to 2 m, its average annual value changes from 20 to 340 mm, incl. for the warm period (April - October) from 14 to 310 mm. Undoubtedly, such participation of HW in the total evaporation can compensate for almost any number of HW balance incoming items that is formed during irrigation. The only question is when this compensation occurs and the accumulation of salts occurs with it or not. From an ecological point of view, accounting for HW in total evaporation and the ability to control this process are of fundamental importance.
Since the reclamation state of lands depends on the position of groundwater and its change in the future, the GWL forecast is an integral part of the operation of the irrigation system.
With systematic monitoring of the state of groundwater in the online mode, it is possible to build a map of groundwater levels (GWL).
The procedure for constructing such a field of heights can be carried out using standard operations of raster algebra (Map Algebra) in the presence of the relief of the territory under consideration and observations of the depth of groundwater in wells [4]. According to the results of the research, digital maps were constructed, reflecting the change in the depth of groundwater in the study area (Fig. 1).
The direction of the ground flow changed, if in 2016 filtration from the canal towards the irrigated area was observed, then when irrigation was stopped and the drain was emptied, its draining role was restored.
In addition, an important information characteristic for local monitoring is the chemical composition of groundwater, since the accumulation of salts in groundwater leads to secondary salinization of irrigated lands.