Abstract

The synoptic situation that developed in the summer of 2019 in the southwestern areas of Irkutsk oblast region, in the mountains and foothills of Eastern Sayan, was responsible for heavy rainfall that caused extreme flooding on the Iya river. A landscape-hydrological analysis of the territory was made. It was found that topography, morphology and structure of soil and vegetation cover have a considerable influence on the hydrological regime of the river and on the formation of the flood runoff. An important role for the operation of the hydrological functions of landscapes in the formation of this flood is played by the intensity, duration and spatial differentiation of precipitation, coupled with the state of the underlying surface within the Iya basin. During the period of extremely high precipitation, the landscapes of most of the catchment were characterized by a significant humidification resulting from preceding precipitation, which reduced their regulation and accumulation capacity. Goletz, subgoletz and mountain-taiga larch landscapes on frozen tundra soils of the northeastern macroslope of Eastern Sayan which are characterized by large slope angles, sparse vegetation and a shallow soil layer, are distinguished by large water yield in conditions of heavy precipitation. A significant flow-regulation potential of mountain-taiga dark coniferous landscapes of gentle slopes and low mountains, and also the accumulating properties of meadow‒marsh complexes of foothill depressions and valleys were realized during the previous precipitation events and did not have a significant regulatory effect during the formation of the flood at the end of June. Hilly-ouval topography and a high groundwater level in the middle part of the basin are the factors promoting flooding thus impeding infiltration and outflow of water.

中文翻译：

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2019年6月伊亚河洪水形成条件的景观水文分析

摘要

2019年夏季，伊尔库茨克州西南部地区，东萨彦岭的山麓和丘陵地区出现了天气情况，这是造成大雨的原因，造成了伊亚河的极端洪灾。对该领土进行了景观水文学分析。研究发现，土壤和植被覆盖的地形，形态和结构对河流的水文状况和洪水径流的形成有相当大的影响。降雨的强度，持续时间和空间分异以及伊亚河流域内下垫面的状态对洪水形成过程中景观水文功能的运行起着重要作用。在极高的降水期间 大多数集水区的景观特征是前期降水导致了明显的增湿，从而降低了它们的调节和蓄积能力。东萨彦岭东北部大斜坡的冻冻苔原土壤上的戈莱茨，次戈莱茨和塔伊格山落叶松景观具有较大的坡度角，稀疏的植被和较浅的土壤层，其特点是在强降水条件下的高产水量。在先前的降雨事件中，实现了缓坡和低山的针叶林暗针叶林景观的显着的流量调节潜力，以及丘陵洼地和山谷的草甸沼泽复合体的积累特性，并且没有明显的调节作用。在六月底的洪水形成过程中。