Changes in river flow resources under the influence of natural, climatic and anthropogenic factors (the Chumysh River as a study case)

Studies of the dynamics of water regime of rivers, as one of the key components of water resources, are of particular importance under global climate change. Rational water use and adaptation of water management systems call for understanding the patterns of runoff changes caused by both natural and anthropogenic factors. The aim of the study is to identify the features of the long-term dynamics of the Chumysh River runoff in the context of a changing climate and anthropogenic impacts, with an emphasis on its intra-annual redistribution. Methods. The paper deals with analyzing the meteorological and hydrological data (1943–2021) on checking the stationarity of time series, assessing linear trends, constructing difference-integral curves and calculating the coefficients of natural regulation. Correlation and cross-correlation analyses were also performed to establish relationships between climatic parameters and runoff. Results. We have revealed a statistically significant air temperature rise (especially pronounced in the cold period) accompanied by increased winter runoff, decreased volumes of spring floods, maximum water discharges that result in the increasing natural regulation. Anthropogenic impacts, including flow regulation and water intake, are assessed as weak; they make the insignificant effect on water regime of the Chumysh River. The obtained results confirm the predominant influence of climatic factors and can be used in developing the measures on adaption to climate change.