The exceptionally high spatial-temporal variability of the river runoff and the significance of its transboundary component considerably worsen the problem of the water supply of the republic. Due to the disadvantageous geographical location in the lower reaches of transboundary river basins, the Republic of Kazakhstan is largely dependent on water economy activities taking place in neighbouring countries. In the article the modern change of the resources of river runoff in Kazakhstan, taking into account climatic and anthropogenic influences is considered. For the assessment of the impact of economic activities on the river runoff and changes in climatic-related runoff, the complex of integral methods was used, and appropriate methodologies were developed. The obtained results of the modern influence of a complex of factors, as well as their significance for the future (till 2030), can be used for the development of scientifically based solutions for sustainable management and protection of water resources. An assessment of the anthropogenic activity of this study shows that the water resources of the river runoff of the Republic of Kazakhstan have decreased by 16.0 km 3∙y –1. According to our forecasts, there will be a further decrease in the water resources of the republic due to the expected decrease in transboundary flow to 87.1 km 3∙y –1 by 2030, in dry years less than 50.0 km 3∙y –1. We propose a set of measures to prevent the negative impact of possible reduction of river runoff resources in the future in the water basins of Kazakhstan.

The role of river runoff resources is very important for Kazakhstan – the country located deep within the continent, with an arid climate, and experiencing water shortage. With such a geographical location, the hydrological regime of rivers is characterized by the considerable spatiotemporal variability, thereby complicating the water resousrces management. The issue of evaluating water resources is particularly relevant not only from a scientific point of view. In recent years, it has gained socio-economic and political nature due to the increasing role of anthropogenic factors (including geopolitical ones), as well as increasingly more noticeable changes in the global and regional climate. Based on hydrometric information using modern methodology, the water resources of eight water-resources basins (WRBs) on the territory of Kazakhstan have been estimated in the context of water-resources regions.

Runoff formation is a complex meteorological-hydrological process impacted by many factors, especially in the inland river basin. In this study, long-term (1960–2015) river runoff and climate data in the Arys and Keles River watersheds (Kazakhstan) were gathered to analyze the impacts of climate variation and human activity on runoff. The non-parametric Kendall test and the Pettitt test were used to identify trends and change points in the time data series. It was found that both watersheds had significant upward trends in temperature and potential evapotranspiration data, and insignificant upward trends in the runoff. Change points in annual runoff were identified around the year 1973. The hydrological sensitivity method was employed to evaluate the impacts of climate variation and human activity on mean annual runoff based on precipitation and potential evapotranspiration. It was found that the decline in annual runoff over both catchments can be mainly attributed to human activity, the reduction percentages due to human activities range from 59% to 99%. The results of this study can provide a reference for the development and water management of the regional water resources.

The global water crisis, which intensifies each year, underscores the urgent need for accurate assessment and sustainable management of freshwater resources. Lakes, as significant components of surface water systems, are particularly vulnerable to human activities and climate change due to their slow renewal rates. Western Kazakhstan, a region affected by economic development and intensive mining activities, faces acute water scarcity. A reliable water supply is crucial to meeting the requirements of industrial operations and the needs of the region’s population. Understanding the dynamics of lake systems and implementing effective conservation and restoration strategies are essential to addressing this challenge. This study, employing cartographic and remote sensing techniques, identified 323 lakes in Western Kazakhstan, covering a total area of 1944 km². Comparative analysis with historical data from the 1960s and 1970s revealed a 23% decrease in the number of lakes exceeding 1 km². The most significant decline was observed in the Atyrau and Mangystau Regions, where the number of such lakes diminished by a factor of three. These findings highlight the pressing need for an integrated, interdisciplinary approach to water resource management in Western Kazakhstan.

The surface water resources of the West Kazakhstan Region (WKR) face escalating vulnerability due to the synergistic effects of a sharply continental climate, which intensifies climate change impacts, and rapidly increasing anthropogenic water demand. This study aims to quantify and project the future water stress on WKR’s surface waters, assessing the combined influence of climate change and socio-economic development over the critical period of 2030–2050. This study presents a comprehensive quantitative assessment and future projection of water stress on the region’s surface waters, integrating state-of-the-art CMIP6 climate scenarios (SSP2-4.5 and SSP5-8.5) with a novel model of water consumption growth accounting for regional demographic and economic developments. Employing advanced bias-corrected ensemble climate projections alongside physically interpretable water balance models, we estimate changes in river flows and lake volumes through mid-century. A newly developed Water Stress Index (WSI), supplemented by the Falkenmark Index, reveals an alarming increase in water stress, with projections indicating that over 70% of the WKR territory may face severe resource limitations by 2050. The analysis underscores significant spatial heterogeneity driven by climatic variability and socio-economic factors, emphasizing the urgent need for regionally tailored adaptation and water management strategies. These findings provide a robust scientific basis to guide policy decisions aimed at mitigating future water scarcity under evolving climate and development scenarios.

Международно-правовая основа должна обеспечивать справедливый, разумный, экологически устойчивый и обязательный для всех сторон режим водопользования и вододеления. При этом необходимо учитывать потребности самой природы в воде с целью сохранения и умножения биопродуктивности и биоразнообразия. Другими словами, сохранение естественного характера стока реки как природного объекта. Изъятию подлежит лишь экологически допустимый объем водных ресурсов с учетом обязательных потерь стока и экологических требований дельты. Для сохранения речных экосистем важнейшей задачей становится научное обоснование допустимых объемов изъятия и экологического стока рек. Процесс оценки экологического стока очень сложный, ресурсоемкий и для определения показателей экологического стока в регионе, в конкретной стране и в трансграничных бассейнах, охватывающих несколько стран, является важным подбор методик. В статье рассмотрены вопросы и сделан обзор определения экологического стока. Выполнен обзор методики нормирования экологического стока. Приведен общий алгоритм расчета для различной обеспеченности стока. Получены значения экологического стока и объем предельно допустимого изъятия речного стока различной обеспеченности для замыкающих створов рек Сырдария, Арыс и Келес.