Abstract

The trends in river runoff during the winter lower water period in the Ural River basin have been analyzed in this work. The long-term dynamics of the runoff parameters has been studied. Concurrently, consideration has been given to the phases with a different river water content. It was found that the water regime of the rivers in the study basin is characterized by a stable trend of a decreasing share of the spring runoff and an increasing share of the winter runoff. The growth of the share of winter runoff is caused by an increase in the frequency and duration of positive temperature anomalies and the share of basic (underground) river feeding. Comparison of the annual runoff and 30-day values of the minimum runoff in the winter period illustrates a certain interdependence in the changes of their values. In spite of the general trend of the increasing winter low water discharges, certain differences have been revealed for the rivers of the basin studied due to the heterogeneous conditions under which the runoff is formed. The regional features of the formation of the winter low water runoff confirm the different dates for occurrence of the maximum (complete) depletion of the river runoff. The significant increase in the water content of the rivers in winter affects the decrease in the variability of daily discharges, which is consistent with the previously established trend of decreasing interannual variability of the river runoff in the basin of the Ural River. The increase in the winter low water runoff is of great practical importance, because the runoff value for a given period is the limiting factor that determines the guaranteed and sustainable water consumption. Accordingly, the current trends in the change in the water regime of the rivers of the Urals basin must be taken into consideration when determining the regulations and norms for the use of water resources in the steppe zone.

中文翻译：

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乌拉尔河流域冬季低水期河流径流变化

摘要

本文分析了乌拉尔河流域冬季低水期河流径流的变化趋势。已经研究了径流参数的长期动态。同时，考虑了不同河流含水量的阶段。研究发现，研究流域河流水情呈现春季径流占比下降、冬季径流占比增加的稳定趋势。冬季径流份额的增长是由正温度异常的频率和持续时间以及基本（地下）河流补给份额的增加引起的。年径流与冬季最小径流30天值的比较说明它们的值变化具有一定的相互依存关系。尽管冬季低水流量总体呈增加趋势，但由于形成径流的非均质条件，流域内的河流已显示出某些差异。冬季低水位径流形成的区域特征证实了河流径流最大（完全）枯竭发生的不同日期。冬季河流含水量的显着增加影响了日流量变异性的减小，这与先前确定的乌拉尔河流域河流径流年际变异性减小的趋势是一致的。冬季低水径流的增加具有重要的现实意义，因为给定时期的径流值是决定保证和可持续用水量的限制因素。因此，在确定草原区水资源利用的法规和规范时，必须考虑乌拉尔流域河流水情变化的当前趋势。