Azizdzhan fazilovich babadjanov

Aquifer of Upper Pliocene deposits. Interstratal pressure waters confined to the Upper Neogene deposits are ubiquitous within the area under consideration and are tapped by numerous wells within the area of work, as well as outside it. Water-bearing rocks are gray and light yellow sandstones with interlayers of brown siltstones and clays. In the rest of the area, their depth varies from 50 to 235 m.
The thickness of aquifers, according to the work of the Shorsay and Karshi hydrogeological parties of the Kyzylkum expedition, is 20–38 m. The mineralization of the Neogene groundwater is very diverse. Within the study area, as well as on the Karabair structure located north of Kasan, the waters of the Upper Neogene have a dense residue of 1.5–5 g/l, in the area of the Karshi railway station - 6–11 g/l.
Features of the chemical composition of groundwater. The results of the chemical analysis of groundwater, obtained in the course of this dissertation research, showed that their dry residue varies from 1110.0 to 11430.0 mg/l. The content of SO ₄ ^{-2 ions} is 386.0–4360.0 mg/l, while the content of C l ions ^is –177.2–1276.2 mg/l. According to KMK 2.03.11-96 ², groundwater in terms of sulfate content is standardized as highly aggressive to concrete, according to GOST 10178-85 ³, and non-aggressive to concrete for sulfate-resistant cements according to GOST 22266-2013 ⁴. In general, in the city of Karshi and the territory adjacent to it, the mineralization of groundwater is on average 3.0 g/l.
An analysis of the change in mineralization, chemical composition and pollution of groundwater gives grounds for the following conclusion: the mineralization of groundwater throughout the study area remains high and amounts to 1.5–10.0 g/l; the regime of mineralization and chemical composition of groundwater is relatively stable over time; The western part of the area of the district is allocated for irrigation, and in these territories, as a result of the use of various mineral fertilizers, the quality of water is gradually deteriorating. Since the studied area is intensively irrigated for a long time, and the groundwater level lies close to the surface of the earth, secondary soil salinization and areal flooding occur. Over the past 10 years, the groundwater level has been in the range from 0.5 to 3.0 m from the earth's surface. Only in 2010–2011, which were dry, the fluctuation amplitude was 1.3 m, mineralization was in the range of 5.0–8.0 g/ l . In 2017 , for 9 months, the fluctuation amplitude was 1.0 m.
Thus, based on the analysis, it can be concluded that the hydrogeological conditions of the Kashkadarya river valley are determined, on the one hand, by the geological and geomorphological structure, and on the other hand, by the development of the hydrographic network and climatic factors.
Within the limits of the modern valley of the Kashkadarya river, the main supply of groundwater is carried out due to a powerful underground inflow from the side of mountain frames. The flow of groundwater moves from the side of the mountains and in a westerly direction to the center of the basin with a general discharge to the west. A relatively powerful flow of groundwater is confined to a narrow strip of the modern channel of the Kashkadarya River, the formation of which occurs within the Kitabo-Shakhrisabz basin.
Groundwater (WW) occurring in Quaternary sediments form a single powerful water flow. The thickness of the aquifer is from 10 to 45 m with salinity from 1 to 3 g/l. Within the city, the groundwater regime is closely linked to the irrigation regime of both cotton and other agricultural crops. Irrigation is usually carried out in summer and autumn, infiltration contributes to an increase in the level of groundwater to its maximum value. In most of the territory, the groundwater level lies in the range from 1.0 to 3.0 m with a mineralization of 1.5–5.0 g/l.
Currently, vertical drainage wells operate within the city, but no effective result in changing the parameters of the seasonal regime has been obtained. During the period from April to May, in the studied area, the groundwater level lies at a depth of 1.0–7.0 m, depending on the terrain. Near the Kashkadarya River, the groundwater level was noted at a depth of 3.0–4.5 m. At elevated places in the central part of the city of Karshi, the groundwater level was noted at a depth of more than 5.0 m, and at some points - 10.8 m. According to regime observations, the highest position of groundwater levels is observed in May-June, the lowest - in October-December. The amplitude of groundwater level fluctuations is 0.43–1.89 m.
Based on long-term regime data and hydrogeological conditions of the city of Karshi and the calculated maximum, the groundwater level should be expected at a depth of 0.3–6.3 m [14; With. 221-224] . Regime monitoring of the level of groundwater in wells No. 730 and 131, an increase in the level of 0.6 m. This is due to the irrigation of areas to the east of the city, from where the flow of groundwater moves to the west and southwest. The hydrodynamic regime of the city's groundwater was studied using observation wells No. 47, 64, 102, 131 721, 730. In well No. 730, located in the southwestern part of the city near the airport, over the past 12 years, the average long-term level was 1.45 m. The maximum average annual amplitude was observed within 1.73 m. For well No. 131k, located in the Shurtan microdistrict, the average long-term level was 2.09 m, level rise - 0.23 m, maximum oscillation amplitude - 2.71 m. For well No. 64v, located in the western part of the old bazaar in the mahalla Zo gd a, the average annual level for the last 12 years was 7.59 m. In this case, the maximum oscillation amplitude was observed within 1.19 m. For well No. 102, located in the eastern part of the city, the average annual level is 9.60 m, the maximum amplitude of oscillation is 1.20 m.
The results of observations of the groundwater level showed that in the central and southwestern parts of the city (military camp, regional trauma hospital, settlement Shibaev and Mekhanizatorov, district of the railway station and airport) the level of groundwater was above the critical depths by 2 m. An increase in the level was observed in 20 1 3 d. This was due to an increase in water supply and precipitation. The results of studying the hydrodynamic regime of groundwater in characteristic wells of the city of Karshi (average annual level of groundwater, m) are given in Table. 2. 2. and in fig. 2.5.
Table 2.2
Results of the study of the hydrodynamic regime of groundwater

No. p/p	Year	Well No. 730	Well No. 131k		No. p/p	Year		Well No. 730		Well No. 131k
1	2000	1.75	2.02		eleven	2010		1.36		1.93
2	2001	1.87	2.36		12	2011		1,44		2,33
3	2002	1,41	2,10		13	2012		1,72		2,09
4	2003	1,09	2,08		14	2013		1,73		2,20
5	2004	1,30	1,84		15	2014		1,52		2,31
6	2005	1,20	1,87		16	2015		1,39		2,71
7	2006	1,73	1,96		17	2016		1,51		2,26
8	2007	1,49	1,91		18	2017		1,21		1,81
9	2008	1,42	2,23		19	2018		1,22		1,97
10	2009	1,52	2,01		20	201 9		1.31		1.47
					Medium long-term		1.46		2.07

Figure. 2.5. Graph of changes in the level of groundwater by wells