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CURRENT CLIMATE CHANGE TREND STAGE AND ITS INFLUENCE ON HYDROMORPHOLOGY OF THE KURA RIVER
(AZERBAIJAN)
AYSEL JALILOVA GARIB
Chief researcher, Ministry of Defence Industry of the Azerbaijan Republic, National Aerospace Agency (NASA) of Azerbaijan, Deparment of Special design bureau of Instrument engineering, Baku
Abstract. This article presents the results of the study, obtained by the authors in the process of working on the problem of climate change and its impact on the water resources of small transboundary basins. Problems of climate change impact on the water regime of the Azerbaijan rivers were considered. These basins included the Kura river, which is fed by glaciers and snow, located in Azerbaijan. An attempt was also made to predict changes air temperature and river flow for a long period. Subject to a continuing trend of changes in the main runoff-forming factors - air temperature, precipitation and glaciation. As a result of global climate change, research into changes in hydromorphological parameters in the Kura River, the largest water source of the Republic of Azerbaijan, has become a very relevant topic, and the results obtained can be used as literary data by young scientists.
Keywords: environment, precipitation, air temperature, water resources
Introduction. Climate change is a gradual change in the average characteristics of the factors (temperature, precipitation, evaporation) that determine it over a long period of time. The problem of climate change is relevant not only now, but also in the foreseeable future, both in global and regional aspects [1,2]. Taking into account that Azerbaijan is one of the world's poorest countries in terms of river water resources, it is relevant to study the impact of climate change on water resources, annual river flow, as well as their regimes.
The problem of climate change in the seventies of the last century became global in nature, as signs of climate change began to appear more and more clearly, which resulted in more frequent droughts, catastrophic floods, an increase in the amplitudes of interseasonal air temperature fluctuations with a general tendency to increase both seasonal and average annual, average monthly temperatures [4]. The magnitude of the increase in air temperature is consistent with the forecast of global warming due to an increase in carbon dioxide in the atmosphere, first made more than 40 years ago based on an energy balance model. The warming process that began in the last century continues today, with record above-average global average temperature anomalies [5,6]. The study of patterns of changes in the amount of atmospheric precipitation is associated with some difficulties due, on the one hand, to the large temporal and spatial variability of precipitation, and on the other, to the inaccuracy of instrumental measurements.
According to the shape of the hydrograph, the Kura river belongs to a type with two pronounced phases of the regime - high water (April-September) and low water (October-March). Changing climatic conditions will lead to changes in the water resources of river basins in various regions and countries (Figure 1).
Those changes that are caused by greenhouse gas emissions are irreversible in the foreseeable future. The essence of forecasting is the pre-calculation with varying lead times and degrees of accuracy of one or another climate element (in this case, temperature). Climate warming is already affecting many ecosystems, the state of which depends on the temperature regime - rivers, lakes, glaciers, soil moisture, biodiversity, etc. The Kura River is a transboundary watercourse, the flow of which is used by three states. And how the river flow changes against the backdrop of climate change is of interest to both sides. The following presents the results of an analysis of the river flow and its dynamics in different time periods, as well as a forecast and consultation of the expected
water content for a very long period. At the same time, all available publications of other developers on forecasting were used and the authors' forecast was given. To determine the impact of climate change on precipitation within Azerbaijan, a paired correlation was established between air temperature and the layer of average long-term precipitation.
Methods. Contemporary global climate change, which has an impact on water resources, has also been noted on the territory of Azerbaijan. In the Kura River basin, an analysis of the main climatic parameters - air temperature and precipitation - was carried out at a weather station. The development of forecasting methods and their further use, which make it possible to determine in advance (with a certain lead time) the development of processes and phenomena, is based on observational data in the previous period. This forecast method for such a long period can be taken as a consultation, compiled on the basis of a retrospective analysis of data on the average annual temperature of the observation period, provided that the trend and rate of climate warming (increase in average annual temperature) continues during the forecast period. According to the forecast for climate scenarios, the temperature increase is expected under the A2-ASF scenario by 2050 within the range of 1.8...2.82; according to the B2-MESSAGE scenario within 1.7...2.50. These scenarios are based on projected increases in greenhouse gas emissions, and provide a significant range of projected temperature increases. An analysis of the seasonal water flows of local rivers shows that during the winter low-water period in most of them, water flow increases. With a decrease in annual runoff, an increase is observed in the winter low-water period, and a decrease in the spring and summer months. In some rivers there is an increase in flow in the autumn season.
Results. The trend analysis of the average annual temperature at the Kura river by weather station for the observation period is clearly positive [3]. The temperature increase from the initial 7.00 to the final 9.18°C trend value was 2.19°C (growth intensity 0.020°C/year). The deviation of the average annual temperature for the period 2018-2023 years from the long-term average value, from which we can conclude: the trend of climate warming after 2020 not only continues, but also becomes more significant than over the entire observation period. The climate warming trend continues and is becoming more dynamic character. Difference integral curves of average annual temperature show that the calculation period includes periods of decreasing and increasing temperatures, while the period after 2019 is in a positive phase - an increasing trend. The river flow is formed due to the accumulation of seasonal snow (snow reserves of the cold period). Snow runoff - first phase floods, the second phase - from the melting of glaciers and snowfields the high mountain zone is the glacial component of the runoff. Liquid precipitation (rain feeding) does not play a significant role in the formation of runoff and amounts to 3...5% of the annual volume. Low-water period on rivers fed by glaciers and snow falls during the cold season (October-March), when the thawing process stops and river flow is formed by groundwater in the active water exchange zone. Low water is characterized by stable, low water flows, which decrease towards the beginning of the flood. The duration of low water is up to 195 days. Minimum flows are observed at the end of the low-water period - March, April, when groundwater reserves in the river basin reach exhaustion. The Kura river belongs to the group of rivers with unstable freeze-up. The increase in water consumption is directly related to from the increase in air temperature over the same time periods. The connection is close; the correlation coefficient, reflecting the closeness of the connection, is close to 1 (R=0.97). This connection confirms that the increase in water content in rivers fed by glaciers and snow (the degree of glaciation
basin more than 2...5%) occurs due to more intense melting glaciers against the background of ongoing climate warming. Atmospheric precipitation does not change significantly and generally does not have a decisive role in increasing runoff. Regression equation describing the relationship (y=0.639x+1.38), can be used to calculate long-term average annual runoff using temperature forecast data. By dividing the runoff hydrograph of the Kura river into genetic components (snow, glacial, underground), glacier runoff (July-September) in a year of average water content makes up 53% of the total annual flow. With the complete disappearance of glaciers, the river flow will depend mainly due to the seasonal accumulation of precipitation from the cold period in the high-
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mountain zone (snow runoff) and accompanying precipitation from the flood period - AprilSeptember (snow in the high-mountain zone, rain in the low-mountain zone). As a result, the hydrological regime and intra-annual flow distribution will change, the flood will shift to earlier months (May-June), and glacial floods (July-September) will decrease and during these months there will be a shortage of irrigation water. The variation (variability) of runoff over the years will increase, since the runoff will mainly depend on the amount of precipitation in each particular year, and the role of glaciers as flow regulators in dry years will decrease to a minimum. The loss of glacier area and glacial mass in the future will lead to a decrease in glacial runoff and, as a consequence, to reduction in the water content of rivers of the glacial-snow type of feeding, which has already been noted on rivers in the basins of which there was insignificant glaciation in the form of individual glaciers, small in area and mass. If the trend of rising air temperatures and active melting of glaciers continues, there will be a reduction in the area and mass of glaciers feeding the rivers. The consequences of such a significant projected decrease in surface runoff will negatively affect the living conditions and economic activities in the transboundary river basins in the field of water use, water allocation and hydropower. An analysis of local rivers by food source shows that snow water makes up 39-40%, rainwater 30-36%, and groundwater 32-35%.
Figure 1. Average monthly water flows of the Kura River in different years
water content
Average annual consumption varies from 4.48 to 9.17 m /day, depending on the water content of the year, in a year the average water content is 6.36 m3/day (in the runoff volume this is 141, 288 and 200 106 m3).
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