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1THE IMPACT OF CLIMATE CHANGE ON THE SURFACE WATERS OF THE
SARYSU
ТАУКЕН ЖАНГАСЫР КАРИПОЛЛАУЛЫ
Магистрант кафедры «Физической и экономической географии», Евразийский национальный университет имени Л. Н. Гумилева, Астана, Казахстан
Abstract. This study examines the impact of climate change on the surface waters of the Sarysu River, located in the arid Kazakh uplands. The region experiences a sharply continental climate with extreme temperature fluctuations and limited precipitation, making water availability largely dependent on snowmelt. Climate change exacerbates these issues by altering precipitation patterns, reducing snow cover, and increasing evaporation rates due to rising temperatures. As a result, the hydrological cycle of the river faces increased variability, with more frequent droughts and reduced runoff. This article emphasizes the need for adaptive water resource management strategies to address the growing impact of climate change on the fragile water resources of the Sarysu.
Keywords: Surface structure, Kazakh uplands, Geological processes, Erosion, Relief, Tributaries, Ulutau and Argynaty, Hydrology, Climatic conditions, Continental climate, Temperature, Precipitation, Snow cover, Watershed, Seasonal conditions, Precipitation patterns, Water resources, Water resource management, Hydrological cycle.
This study explores the effects of climate change on the surface waters of the Sarysu River, located in the arid Kazakh Uplands. The region experiences a sharply continental climate, with extreme temperature fluctuations and limited precipitation, making water availability highly dependent on snowmelt. Climate change exacerbates these challenges by altering precipitation patterns, reducing snow cover, and increasing evaporation rates due to rising temperatures. As a result, the river's hydrological cycle faces increased variability, with more frequent droughts and reduced runoff. This paper highlights the need for adaptive water management strategies to address the growing impact of climate change on the Sarysu's fragile water resources.
Surface Structure.
Sarysu is a river of the Kazakh Uplands (or Kazakh Folded Country). Hills and their ridges flank the river for a significant portion along both banks.
The Uplands represent a plain with remnant mountains and hills. This is a peneplain, remnants of a large mountainous region, eroded over time and shaped by denudation and erosion processes, partially buried under loose sediments.
Hills with dome-shaped or cone-shaped peaks rise above the surrounding landscape by 30-40 meters, sometimes reaching heights of 80-100 meters. They often form ridges, predominantly oriented in a meridional direction. The hills and ridges stand out against the undulating plain. The slopes of the hills are covered with gravel, and bedrock is exposed on their peaks. Against the background of the hills, mountain uplifts, ridges, and isolated low mountain massifs are visible. Of the two low mountain ridges in the Uplands, the southern one belongs to the Sarysu basin.
( Figure 1.)
Physical map of Sarysu river basin. Figure 1.
In the western part of the Kazakh Uplands, the Ulutau Mountains (up to 1135 m in height) and the Argynaty Mountains rise. From their eastern slopes flow the tributaries and feeders of the most water-abundant river in the Sarysu system—the Kara-Kengir River. On the western slopes, the tributaries and feeders of the Ulyzhylan-Shik and Turgay rivers, which belong to the neighboring basin of the endorheic Shalkarteniz depression, originate.
The sources of the Sarysu tributaries in the eastern part of the basin are located in the Buguly Mountains (the highest point is 1184 m—Mount Burkitty), the Zhaksytagyl (up to 1076 m— Agadyrskaya Expedition Mountain), Kosmurin, and Ortau (the highest point is 1068 m). The river is also fed by streams from the Aktau Mountains. These are merely peripheral mountains of the Kazakh Folded Country. The main mountain massifs and ridges lie outside the basin and feed other rivers with their moisture.
Upon reaching the desert, Sarysu sharply turns south and flows along the western edge of the Betpak-Dala plateau. Betpak-Dala is the northern part of the Hungry Steppe. The plateau drops steeply into the Sarysu valley with cliffs as high as 40-60 meters. Betpak-Dala is an extensive desert plain with long, gently sloping ridges.
The drainage basin here is inactive. Water runoff does not form; on the contrary, it is lost. The desert is clayey, but on its western edge, sands are widespread, often mobile and wind-blown (called "kumy"). The surface is slightly hilly, with the southwestern part lowered (absolute elevations up to 300-350 m). The landscape is characterized by numerous basins and dry ravines. In the southwestern part, there are many takyrs and sor depressions, as well as small salt lakes.
Climatic Conditions.
From the perspective of runoff formation, the climate is unfavorable. It is sharply continental and arid. The basin is located deep within the Eurasian continent, far from the beneficial, moistening influence of the Atlantic. However, dry subtropical air from the deserts of Central Asia freely penetrates here, as well as moisture-poor Arctic air moving meridionally.
In the warm half of the year, it is dry and hot: air temperatures are high, precipitation is scarce, and the air is dry. The duration of sunshine accounts for 60-70% of the possible amount. Winters are
harsh and frosty. The snow cover is stable but not very thick. Windy conditions are common, as are frequent snowstorms. Transitional seasons, spring and autumn, are short, lasting only about 30 days each.
With a zonal circulation pattern, a distinct belt of high pressure is observed, and baric formations move from west to east. The temperature background is elevated, and precipitation is relatively low. During meridional disruptions in zonality, the area is subject to northwestern and northern incursions, as well as southern ones. Depending on the nature of meridional circulation, precipitation can either increase or decrease, and temperature anomalies can be both positive and negative.
The characteristic values of meteorological parameters are provided in Tables 1-4, in accordance with [11]. Station elevations: Zhana-Arka - 488 m, Zhezkazgan - 345 m, Kyzyl-Zhar -361 m.
Air Temperature.
In both summer and winter months, isotherms run almost latitudinally across the basin's territory. The average annual air temperature in the northern part of the region is approximately 2°C, while in the south, it reaches 6-7°C.
The average temperature in January ranges from minus 15-16°C to minus 13.5-14°C. However, in certain years and on specific days, significant deviations from the norm are possible. Frosts can drop as low as minus 40-47°C. Occasionally, thaws occur in winter with temperatures rising to 4-10°C, which naturally leads to snowmelt.
The average July temperature is 20-26°C. The soil dries out, and summer precipitation practically does not contribute to runoff formation. On certain days in July-August, dry winds blow for 2-4 days in a row, during which the relative humidity drops below 40%, and the air temperature exceeds 23°C.
The absolute annual amplitude of air temperatures exceeds 90°C.
In spring, the air temperature crosses 0°C around April 10. The air warms up quickly, and within 10-12 days, it rises by about 10°C, although during prolonged springs, this period can stretch to 1520 days or even longer.
In autumn, the air temperature typically falls below 0°C around October 29-31. Thus, the period with positive average daily temperatures lasts about 200 days, while the frost-free period ranges from 118 to 180 days.( Table 1).
Table 1
AVERAGE ANNUAL TEMPERATURE OF ZHEZKAZGAN WEATHER STATION FOR THE PERIOD 2000-2023
2,0 1,0 0,0
<$?> ^ <$?> Jp JP ^ ¿V Л? ^ лУ
year
Atmospheric Precipitation
The annual amount of precipitation across the region varies from 150 to 350 mm. In most of the basin, it ranges from 200 to 250 mm (Table 1). Precipitation levels are higher in the headwaters of the rivers. In the Ulutau and Argynaty Mountains, more than 350 mm of precipitation falls, with approximately 350 mm also falling near the village of Atasu. On the steep mountain slopes, precipitation can be 1.5 to 2 times greater than at their foothills and in mountain valleys. Within the Uplands, the western and northern slopes are better moistened, while the eastern slopes receive the least precipitation. For every 100 meters of elevation, precipitation increases by an average of 60-70 mm.
Designations: N - station elevation; T - average air temperature; lmax. p - air pressure; V - wind speed; e - relative humidity; d - air moisture deficit; S - number of sunshine hours; X - total precipitation.
During the warm period, 70-80% of the annual precipitation falls. The highest amounts occur from April to July, with increased precipitation in October. The rainless period can last up to 70 days, and the average number of cloudy days does not exceed 4-5 per month. The total number of days with precipitation in the warm period is 6-10. Summer precipitation is more often in the form of showers rather than continuous rain, with the daily maximum in the Uplands reaching 50-60 mm, while on the plain it reaches 30-35 mm (Table 2). However, as mentioned above, the large air moisture deficit (Table 1) leads to rapid soil drying, and summer precipitation generally contributes little to runoff formation.( Table 2)
Table 2
AVERAGE ANNUAL PRECIPITATION OF ZHEZKAZGAN WEATHER STATION FOR THE PERIOD 2000-2023
30,0 -26,1
.1 25,0
S 20,0
15,0
u
£ 10,0
5,0 0,0
Years
Snow Cover
The snow cover accounts for almost all of the runoff in the Sarysu River, with groundwater contribution being minimal. The distribution of snow cover across the territory is primarily related to latitude, with snow accumulation gradually increasing as latitude increases. However, latitudinal zonality is disrupted due to the terrain.
Along the western edge of the Kazakh Uplands, the latitudinal direction of snow cover isolines shifts to a meridional one.
The first snow usually falls as early as the beginning of October. A stable snow cover typically forms in November, in the southern part of the region by early December, and in some years as late as mid-January. Long-term variations in these dates can be as much as 1.5-2 months.
In elevated areas of the Uplands, stable snow cover lasts 130-150 days, while in the south it lasts 100-120 days. In some years, it may not form at all over large parts of the territory. The average maximum snow depth in the watershed ranges from 15 to 35 cm (Table 3), and the maximum water reserves in the snow cover range from 50 to 120 mm. The highest snow reserves are found in the
22,9
14,4
Ulutau and Argynaty mountains. In the lower reaches of the Sarysu, snow reserves are less than 50 mm.
There are significant variations in late-winter snow reserves over time: in different years, their amounts can vary by 4-5 times, leading to major fluctuations in river runoff. The average dates for reaching maximum snow reserves shift from February 25 in the south to March 13-14 in the north. The main accumulation of snow often occurs in the first half of winter.
Analysis of the Impact of Climate on the Sarysu River Basin
The Sarysu River Basin, located within the Kazakh Uplands, faces significant challenges due to its harsh continental climate and arid conditions. The region's physical structure, climate, and hydrological characteristics combine to create a fragile water system, primarily dependent on snowmelt for its runoff. This analysis explores how these factors interconnect and shape the water resources in the basin.
Surface Structure and Hydrology
The surface structure of the Sarysu River Basin plays a critical role in shaping its hydrological characteristics. The basin is characterized by hills and ridges that rise 30-100 meters above the plains, creating natural features that influence precipitation distribution and water retention. The higher elevations in the Ulutau and Argynaty mountains feed important tributaries, such as the Kara-Kengir River, contributing significantly to the Sarysu's water supply. However, the peripheral mountains within the basin provide limited moisture, leaving much of the region dependent on snowmelt from outside the immediate area.
This topographical configuration highlights the basin's vulnerability. While the higher elevations capture more precipitation, much of the water is lost in the lower, flatter regions where evaporation rates are high, especially in the summer. The landscape's features emphasize the uneven distribution of water resources across the basin.
Climatic Conditions and Water Availability
The climate of the Sarysu River Basin is sharply continental, with extreme temperature variations and limited precipitation. Located deep within Eurasia, the region is far from the moisture-bearing Atlantic air masses, instead receiving dry subtropical and Arctic air. This leads to hot, dry summers and cold winters, with short transitional seasons. Precipitation is concentrated primarily in the spring and early summer months, but this is insufficient to sustain consistent water runoff.
The lack of significant rainfall during the warmer months, combined with the rapid evaporation due to high temperatures, severely limits the basin's water availability. Summers see little contribution to runoff formation, placing even greater reliance on winter snow accumulation. These climatic conditions create a highly variable hydrological system, where water resources fluctuate significantly depending on seasonal and annual variations in temperature and precipitation.
Air Temperature and Precipitation Variability
The extreme temperature range within the basin further complicates water resource management. The article notes that the temperature amplitude exceeds 90°C annually, with winter temperatures dropping as low as -40°C and summer highs exceeding 26°C. This extreme variability exacerbates the challenges of maintaining consistent water supply, as the harsh winters and hot summers create periods of both water scarcity and flooding.
Precipitation levels vary widely across the basin, ranging from 150 mm to 350 mm annually, with the higher amounts found in mountainous regions. However, most of the precipitation falls in the spring and early summer, accounting for 70-80% of the total yearly amount. This uneven distribution of rainfall, coupled with the rapid drying of the soil in summer, limits the effectiveness of precipitation in sustaining river flow.
Snow Cover and Runoff Formation
Snow cover is the primary source of runoff for the Sarysu River. The article highlights how snow accumulation varies by latitude and elevation, with the highest snow reserves found in the Ulutau and Argynaty mountains. Stable snow cover typically forms in November and lasts until March, providing a vital water source during the spring thaw. However, the variability in snow
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accumulation, with differences of up to five times between years, results in significant fluctuations in river runoff.
The unpredictability of snowmelt, combined with the limited rainfall during the warm months, underscores the basin's vulnerability to both droughts and floods. The reliance on snowmelt for runoff formation means that any variations in winter snowfall directly impact the availability of water in the spring and summer. Conclusion
The Sarysu River Basin faces substantial challenges due to its climate and geographical conditions. The sharply continental and arid climate severely limits water availability, with the region heavily dependent on snowmelt for its runoff. The extreme temperature fluctuations and uneven precipitation distribution exacerbate the basin's vulnerability, making water resource management difficult. The article effectively highlights the complex interplay between the region's surface structure, climate, and hydrological dynamics, showing that the basin's water resources are fragile and subject to significant variability.
In conclusion, the Sarysu River Basin's dependence on limited and highly variable snowmelt, combined with minimal contributions from rainfall and groundwater, presents a daunting challenge for sustaining a consistent water supply in this arid environment. Effective water management strategies will be essential to mitigate the impacts of climate variability and ensure the long-term sustainability of the basin's water resources.
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