INTERNATIONAL JOURNAL OF ARTIFICIAL INTELLIGENCE
ISSN: 2692-5206, Impact Factor: 12,23
American Academic publishers, volume 05, issue 06,2025
Journal:
https://www.academicpublishers.org/journals/index.php/ijai
page 1165
УДК
556.535.8
FEATURES OF THE HYDROLOGICAL AND HYDROCHEMICAL REGIMES OF
THE CHIRCHIK RIVER UNDER CLIMATE CHANGE CONDITIONS
А.Аkhmedova
Hydrometeorological Research Institute,
Abstract:
The article presents the results of research on the hydrological and hydrochemical
regimes of the Chirchik river. This research is devoted to a scientific or practical problem, such
as insufficient effectiveness of existing monitoring. Factual data on the concentration of
pollutants, most often exceeding the maximum permissible concentrations, are presented. An
analysis of the study of the spatial distribution of pollutants (PV) along the river length is
presented, which allows for the identification of the most polluted areas. The dependence of the
concentration of pollutants on the water content of the year was considered.
Key words
: pollution, quality, water resources, anthropogenic factor, river, petroleum products,
wastewater, industry, utilities, multi-water, water consumption.
Introduction.
The problem of rational use of water resources and their protection from
pollution is one of the pressing problems of our time.
The decree of the President of the Republic of Uzbekistan states: "The increase in the discharge
of pollutants into water bodies leads to the pollution of open watercourses and, as a
consequence, causes irreparable damage to aquatic flora and fauna, as well as affects public
health"[1].
Currently, there is a need to assess and predict the quality of river water. Currently, there is a
need to assess and predict the quality of river waters, and primarily transboundary rivers. This
also applies to the transboundary Syrdarya River. The issues of protecting and sustainably using
transboundary water resources of the river basin concern the interests of many people living in
the region. This problem is especially relevant for regions with a tense water balance, where the
development of an economic sector may be hindered not only by the quantitative but also by the
qualitative depletion of water resources. Such regions include the Chirchik River basin. The
Chirchik River with its tributaries enters the Syr Darya River basin and is its right-bank
tributary.
After the Chirchik River flows into the Syr Darya River, the territory of the Republic of
Kazakhstan begins after 90 km. Therefore, the Chirchik River's pollution can significantly
affect the water quality in the lower reaches of the Syr Darya River.
Due to the intensive use of the Chirchik River basin's water resources for various purposes and
the discharge of untreated or poorly treated wastewater into the river, the quality of both surface
INTERNATIONAL JOURNAL OF ARTIFICIAL INTELLIGENCE
ISSN: 2692-5206, Impact Factor: 12,23
American Academic publishers, volume 05, issue 06,2025
Journal:
https://www.academicpublishers.org/journals/index.php/ijai
page 1166
and groundwater is deteriorating over time. In some areas, the river water has become
unsuitable not only for fish farming, which places stricter demands on water quality, but also
for domestic and drinking water supply.
Object of research. The Chirchik River basin is located in the north-eastern part of the Republic
of Uzbekistan. (Fig. 1). From a hydrological point of view, the river belongs to the most well-
studied river basins of Central Asia.
Fig-1. Location of the study object
The basin area of the river is 14900 km2, length -161 km [10]. The river flows through an area
with intensive economic activity. Even in the drain formation zone, there are objects that are
sources of pollution. The Chirchik River basin district is the largest industrial center of
Uzbekistan. The main place in its complex economic complex is occupied by industry and
agriculture. Here, almost all the republic's machine-building products serving cotton growing
and the cotton processing industry are produced, and machines for the mining, chemical, food,
and light industries are manufactured.
Multidisciplinary agriculture occupies an important place in the district's economy. The
total area of irrigated land in the Tashkent region is 399.2 thousand hectares, which is 9.15% of
the total area of the Republic. About 4 million people live in cities, more than 1 million in rural
areas, the population density here is very high - about 200 people per 1 km2. The entire
economy of the region is closely linked to the intensification of water use. The high degree of
Chirchik River water use leads to its intensive pollution by wastewater discharges. In the
prospective plans for the development of the sectors of the republic's economy, the issue of
water source purity will be a primary problem as the basis of balance in the ecological situation
of the basin [2].
Household wastewater, industrial wastewater, and agricultural wastewater have a
significant impact on water quality. These factors have a noticeable impact on the nature of
surface water pollution.
One of the significant sources of river water pollution is also the discharge of collector-
drainage waters from numerous irrigated areas of the Tashkent region. Irrigated lands in the
INTERNATIONAL JOURNAL OF ARTIFICIAL INTELLIGENCE
ISSN: 2692-5206, Impact Factor: 12,23
American Academic publishers, volume 05, issue 06,2025
Journal:
https://www.academicpublishers.org/journals/index.php/ijai
page 1167
Tashkent region are mostly not saline, so the existing collector network can fully handle land
leaching.
The most characteristic features of the climate of this territory are its continentality, as well
as the abundance of heat throughout the growing season. In the foothills, an average of 435-514
mm of precipitation falls annually, while in the mountains it is 895 mm and more. In the plains,
there is a shortage of moisture in most years. In summer, in July-August, there is practically no
precipitation. Changes in Air Temperature and Precipitation Using the Tashkent Meteorological
Station as an Example Meteorological observations have been conducted since the late 19th
century. Figure 1 shows graphs of Tashkent GMS for as an example 2013-2023
Figure 1. Average long-term trend of average
air temperature for 2013-2023
Changes in air temperature at this station are
observed in a positive trend. Over 150 years, the average annual air temperature in Tashkent
has increased by 1.2°C. During periods of warming, the amount of atmospheric precipitation
has not undergone significant changes [12].
Subject of research
. Study of the spatial (along the river) distribution of pollutants (PV). This
is of greatest interest, as it allows us to identify the most polluted areas, hypothesize possible
sources of pollution, and subsequently identify them, as well as propose measures for protection
from pollution and cleaning.
Materials used
. In this study, the results of ground data from Uzhydromet's hydrological posts
and water quality observation points in the Tashkent region were used [4]
Research methods
. The work used mathematical statistics, cartographic methods, and
generalized methods for assessing the hydroecological state of the water div.
Main results and their discussions
. To characterize the hydrological regime, we selected a
series of observations of water flow at the Gazalkent hydropost from 1991 to 2021. The upper
watershed of the Chirchik river mouth is outside the zone of anthropogenic influence and
characterizes the natural regime of the river [11].
INTERNATIONAL JOURNAL OF ARTIFICIAL INTELLIGENCE
ISSN: 2692-5206, Impact Factor: 12,23
American Academic publishers, volume 05, issue 06,2025
Journal:
https://www.academicpublishers.org/journals/index.php/ijai
page 1168
Figure 2 Chronological course of average annual water discharges of the Chirchik River
for 1991-2021 (Gazalkent)
A negative trend is observed in the changes in average annual water discharges for the Chirchik
River (Figure 2). During the period under study, the hydrological regime of the studied rivers
was characterized as follows: low-water - 2008 and high-water - 1994, and medium-water -
2015.
Fig. 3. Spatial change in nitrite concentration over the characteristic years in the Chirchik River
Analysis of the obtained data on the intra-annual distribution of water discharges showed that
the Chirchik River floods occur in May-August. This depends on the type of river feeding. As
the Chirchik River belongs to the snowy-glacial type of feeding, it is due to the peak flow
during the summer months due to the melting of glaciers (see Figure 3).
INTERNATIONAL JOURNAL OF ARTIFICIAL INTELLIGENCE
ISSN: 2692-5206, Impact Factor: 12,23
American Academic publishers, volume 05, issue 06,2025
Journal:
https://www.academicpublishers.org/journals/index.php/ijai
page 1169
Fig. 4 Situational diagram of the Chirchik River with an indication of water
quality monitoring points
To date, the state of surface water quality of the Chirchik River is assessed at 9 observation
points of the Uzhydromet (see Figure 1), and for the study of water quality, we have selected 6
main channels on the Chirchik River from its upper reaches to the mouth
1. Gazalkent city - 0.3 km above Gazalkent city;
2. Chirchik city - 0.5 km below the city, 3.0 km below the "Maxam-Chirchik" JSC wastewater
discharge;
3. Tashkent city - higher than the city;
4. Tashkent city - within the city limits, 3 km below the Sergeli industrial zone embankment;
5. Novomikhaylovka settlement, 1.6 km below the settlement;
6. Chinoz city - 3.5 km from the mouth (Figure 4).
Based on the results [2,7,8,9] and our own research, CОD (chemical oxygen demand- an
integral indicator of water quality characterizing the content of difficult-to-oxidize organic
substances), BOC
5
(biological oxygen consumption over five days - an indicator characterizing
the content of easily-oxidizing organic substances) were adopted as the main controlled
indicators. In addition, the actual concentrations of petroleum products, from heavy metal ions -
copper ions, nitrogen-containing pollutants of both industrial and organic origin (nitrates,
nitrites, ammonia) were studied.
One of the important integral indicators characterizing the state of water quality is the
biological oxygen consumption (BOC). By the magnitude of this indicator, one can judge the
presence of easily oxidizing organic substances in water. However, throughout the entire
Chirchik riverbed, the concentration of BOC and COD does not exceed the maximum
permissible concentration (MPC). Figure 5 shows the distribution of average long-term BPK
and CPK values along the length of the Chirchik River [4].
INTERNATIONAL JOURNAL OF ARTIFICIAL INTELLIGENCE
ISSN: 2692-5206, Impact Factor: 12,23
American Academic publishers, volume 05, issue 06,2025
Journal:
https://www.academicpublishers.org/journals/index.php/ijai
page 1170
Fig. 5
Average long-term change in the concentration of pollutants
along
the Chirchik River
-
концентрация ЗВ
- MPC
It can be confidently stated that Chirchik and its industrial zone, as well as the territory of the
city of Tashkent, have a strong influence on the quality of surface waters to increase the content
of BOC and COD. Analyzing the visual information of the river from the "Maxam-Chirchik"
JSC wastewater discharge point to the "Novomikhailovka" dam, the largest amount of easily
oxidized organic matter enters the river.
Moreover, taking into account the peculiarities of economic activity in this section of the
river, it can be assumed that the main sources of pollution by such organic substances are
agriculture and communal-domestic services. The largest contribution to the pollution of the
river with organic substances in this area is made by these two industries.
The change in oil product concentrations along the river's length shows that the most
urbanized sections of the river contribute the most to surface water pollution. In Figure 5, the
INTERNATIONAL JOURNAL OF ARTIFICIAL INTELLIGENCE
ISSN: 2692-5206, Impact Factor: 12,23
American Academic publishers, volume 05, issue 06,2025
Journal:
https://www.academicpublishers.org/journals/index.php/ijai
page 1171
pollution zones are clearly distinguished. Moreover, the Tashkent city zone contributes the most
to river water pollution. The trend of increasing oil product concentration from the "Maxam-
Chirchik" dam to the "Chinaz" dam indicates insufficient reliable protection of the water source
from this type of pollution.
The main sources of ammonium nitrogen in the Chirchik River basin appear to be
concentrated in the upper reaches above the "Maxam Chirchik" JSC discharge - 0.51 mg/dm
3
.
Below this channel or such sources are absent or do not have any significant impact on water
quality. For this very reason, the spatial distribution graph appears so flat, with a clearly
expressed tendency to decrease concentration below the 2nd channel towards the mouth of the
river (see Figure 5).
A high content of copper ions in a section, where it would seem that at least they should
not be found in high concentrations (1.90 μg/dm3), may indicate either natural pollution or a
non-specific source of copper ions entering surface waters. These may be either abandoned
workings or tailings from old processing plants.
Regarding the sharp increase in the concentration of copper ions in section 2, this
increase is apparently related to the discharge of industrial wastewater in this area, or to the old
wastewater collectors containing high concentrations of copper ions in the industrial areas of
Chirchik city, and their possible leaks, including filtration losses. If we consider the age of the
deposits, the geology of the riverbed base, and the close relationship between the surface and
underground tributaries of the Chirchik River, the appearance of increased concentrations of
copper ions along the entire length of the river is not surprising.
Table 1
Limits of fluctuation of pollutants in the water of the Chirchik River (1991-2021)
Hydraulic
solutions
COD
BOC
petroleum
products
nitrites
copper
min
max
min
max min
max
min
max
min max
1
1,5
4,82
0,39
1,72 0,01
0,14
0,001
0,08
0,01
3,6
2
2,6
12,6
1,04
5,12 0,02
0,18
0,019
0,36
0,9
4,4
3
3,93
9,3
1,38
6,2 0,04
0,19
0,04
0,137
0,3
4,3
4
3,81
12,7
1,62
6,35 0,02
0,11
0,08
0,358
0,01
3,4
5
2,6
12,68 1,62
4,53 0,01
0,24
0,014
0,201
0,5
3,8
6
3,8
13,37 1,27
5,29 0,01
0,24
0,004
0,328
0,6
4,2
REM
15,0мг/дм3
3,0мг/дм3
0,02мг/дм3
0,02мг/дм3
1,0
мкг/дм3
Along the river's length, a steady increase in nitrate nitrogen concentration is observed from the
upper reaches to the mouth, and throughout the entire river, the nitrate nitrogen concentration
does not exceed the REM [5].
Discussion.
The constant increase in concentration from the upper reaches to the lower
ones, starting from the city of Gazalkent towards the city of Tashkent, with all certainty,
indicates a constant increase in the volume of pollutants containing nitrite forms of nitrogen-
containing substances entering surface waters (Table 1).
Based on the analysis of changes in nitrite nitrogen concentrations in the surface waters
of the Chirchik River, it can be said with a certain degree of certainty that the main sources of
INTERNATIONAL JOURNAL OF ARTIFICIAL INTELLIGENCE
ISSN: 2692-5206, Impact Factor: 12,23
American Academic publishers, volume 05, issue 06,2025
Journal:
https://www.academicpublishers.org/journals/index.php/ijai
page 1172
pollution by this form of nitrogen-containing pollutants are concentrated in the section of the
river below the "Maxam-Chirchik" JSC discharge and above Tashkent city, and the increased
nitrite content in the Chinoz channel may be caused by discharges of polluted wastewater.
Considering that the main source of such pollution in the conditions of the Chirchik
River basin is wastewater containing fecal pollutants, it can be said that the protection of
surface waters from untreated or poorly treated municipal wastewater is unsatisfactory.
Fig. 6. Spatial change in nitrite concentration over characteristic years
(Chirchik River, Gazalkent gauging station)
In Figure 6, it was established that in high-water years, the nitrite concentration decreases
(increase in REC 1.6 times), in medium-water years (increase in REC 4.9 times), and
conversely, in low-water years, the concentration value increases (increase in REC 7 times).
This indicates that under changing climate conditions, the river's sanitary condition depends on
the year's water content. The lower the water content, the higher the concentration of pollutants.
In order to maintain a favorable ecological situation and the required water quality in the lower
reaches of the Chirchik River, special discharges of the minimum water volume along the
riverbed are provided, which is called sanitary (ecological) discharge [6]
Conclusion.
1. The analyses we conducted allowed us to determine the list of pollutants (nitrites,
petroleum products, and copper ions) that most often exceed the maximum permissible
concentrations and have a dominant influence on the formation of surface water quality
indicators in the Chirchik River.
2. Based on the results of the analysis of the spatial distribution of pollutants, it was
possible to identify the most polluted areas (Chirchik, Tashkent, and Chinoz cities) and possible
sources of pollution (wastewater discharge from the "Suv ta'minot" branch of the Chirchik
Aeration Station, the Bektemir treatment plant, and the "Maxam-Chirchik" JSC treatment plant).
These results allow for their further identification and, moreover, to propose measures for
protection from pollution or cleaning.
INTERNATIONAL JOURNAL OF ARTIFICIAL INTELLIGENCE
ISSN: 2692-5206, Impact Factor: 12,23
American Academic publishers, volume 05, issue 06,2025
Journal:
https://www.academicpublishers.org/journals/index.php/ijai
page 1173
3. Water contaminated with untreated municipal and domestic wastewater can serve as a
cause of infectious diseases and even their epidemics. In the mouth of the river, pond fishing is
developed: in artificially created shallow water bodies, separated by temporary dams from the
main channel of the Chirchik River. Pollution can cause significant damage to the fish
population.
4. The banks of the Chirchik River are densely populated and, as our surveys have
shown, have numerous restaurants, unauthorized quarries, cafes, and dacha buildings with small
poultry and livestock farms. All household wastewater, including fecal wastewater, is
discharged into the river without any treatment; of course, no account is taken of all these
numerous discharges, and the water quality in the Chirchik River deteriorates from them,
especially in terms of nitrogen-containing substances. The "Maxam-Chirchik" plant, Chirchik
city's aeration station, and the Bektemir treatment plant, Salar aeration station have significant
impact on their concentration.
5.
It has been established that in high-water years, the nitrite concentration decreases,
and conversely, in low-water years, the concentration value increases. This suggests that under
changing climate conditions, the river's sanitary condition depends on the year's water content.
REFERENCES:
1. Decree of the President of the Republic of Uzbekistan UP No. 5863 dated October 30,
2019 "On approval of the concept of environmental protection of the Republic of
Uzbekistan until 2030”.
2. Axmedova T.A., Shetinnikov A.A. Current ecological state of the Chirchik River // Jurnal
“Ekologicheskiy vestnik” №3, Tashkent. 2017.— P.40-43.
3. Axmedova T.A., Vidineeva Ye.M., Gafurov A.A. Flooding of the Chirchik River by
Biogenic Vessels / Proceedings of the International Scientific and Practical Conference
“Modern Problems of Hydrogeology and Monitoring of the Environment in the SNG
Transit Environment” -Sankt-Peterburg, 22-24 October. 2020 у. — P 289-293.
4. Hydrological yearbook. Vol.5. River basins of Central Asia. Issue 9. Uzhydromet. 1991-
2021у
5. 6. Methodological principles for assessing and regulating anthropogenic impact on the
quality of surface waters // Edited by A.V.Karausheva. -L.: Gidrometeizdat.1987. —286 p.
6. 7. Markin V.N., Ratkovich L.D., Sokolova S.A. Integrated use of water resources and
protection of water bodies // Moscow. 2015. 316 p.
7. 8. Rubinova F.E. Ivanov Yu.N. Water quality of the rivers of the Aral Sea basin and its
change under the influence of economic activity. Tashkent, 2005. —185 p.
8. 9. Chembarisov E.I., Raximov M.N. Features of hydrological and hydrochemical
monitoring of surface waters of the middle reaches of the Syr Darya River.Tashkent,
«Navruz». 2019. —91p.
9. 10. Shilkrot G.S., Yasinskiy S.V. Spatiotemporal variability of nutrient flow and water
quality in a small river //Vodnie resursi, 2002. tom 29. №3. — P.343-349.
10. 11.Shuls V.L. Rivers of Central Asia. L.: Gidrometeoizdat 1965.- 691p.
11. 12. Akhmedova T, Akramova I., Radjabov A., Mavlyanova D. Assessment of the hydro-
ecological state of piedmont rivers of the Republic of Uzbekistan in the context of climate
change, International Scientific Conference "Construction Mechanics, Hydraulics and
INTERNATIONAL JOURNAL OF ARTIFICIAL INTELLIGENCE
ISSN: 2692-5206, Impact Factor: 12,23
American Academic publishers, volume 05, issue 06,2025
Journal:
https://www.academicpublishers.org/journals/index.php/ijai
page 1174
Water Resources Engineering". Tashkent
April 25, 2020
ID: 16f3802e-8427-4b16-87a1-
40964dfdf2d8 DOI 10.1088/1757-899X/883/1/012010.
12. 13.Keiser О. Bewertung und Entwicklung urbaner FlieBgewasser. Freiburg i. Br.: Institut
fur Landespflege, 2005. 280 p.
