Occasional Floods On The Rivers Of Russian Plain In The 20^Th –21^St Centuries

Abstract

The article focuses on the study of flood flow changes on the rivers of the European Territory of Russia (ETR) in the last thirty years. This is an extremely important problem, as with floods, whose contribution to the structure of the annual flow of European rivers in recent decades has been increasing, the most destructive floods are associated. On the example of 55 representative hydrological gauge stations located on the ETR in regions with different conditions of runoff formation, the features of both summer and winter floods formation are considered. It has been established that over the past thirty years on the most rivers there has been an intensive reduction in the ratio of volumes and maximum flood discharges in relation to the similar characteristics of the basic runoff. Increased groundwater supply is observed, and the absence of significant freezing of the soil leads to an increase in infiltration. The volumes of flood runoff and the basic runoff become comparable or the proportion of the latter begins to prevail. The main reason for the increase in minimum water discharge is associated with an increase in flood flow under the influence of more intense and prolonged thaws. A distinctive feature of the water regime of recent decades has been the flood peaks in almost any season of the hydrological year. In the middle and southern part of the ETR – in the basins of the Volga, Oka, Vyatka, Don Rivers – there is an increase in low-water flow and in the quota of flood in annual flow. On some rivers of the ETR, the spring flood runoff currently accounts for less than 50% of the annual runoff.

Machine Learning Reveals a Significant Shift in Water Regime Types Due to Projected Climate Change

“…Thus, by the end of the 21st century, at least 73.6% of the study area will transit to different water regime types. The main directions of that transition-interruption of low flow periods by thaws, rain-induced floods or droughts, and earlier and lower spring floods-this agrees with the modern changes in runoff characteristics [24,53,55]. Thus, even following a less aggressive RCP scenario (RCP26), we could be confident in a substantial change of water regime in the northwest of Russia.…”

Fluctuations of Winter Floods in Small Austrian and Ukrainian Catchments

“…In the last decades, the increasing phase in melt temperatures has resulted in decreasing winter floods in Ukrainian catchments, which corresponds well with changes in flood magnitude identified by the author of [2] in Eastern Europe. This study, however, did not find a significant change in flood or snow characteristics as reported in [3] or [40] or North-Eastern Europe [4,5]. The seasonality of winter floods and associated climate characteristics have an extreme inter-annual variability.…”

“…Due to recent climatic warming, changes in the timing of snow accumulation and melt are observed mainly in northeastern and eastern Europe and in mountain regions [3]. Recent analyses in Eastern Europe [4,5] indicate a simultaneous increase in number of winter floods as a result of thawing and a general increase in winter flow volumes. The changes in snow cover are known also to affect the hydrological regime and hence floods, but how this effect varies between regions is still not well understood.…”

Space‐Time Inconsistencies in the Dynamics of Water Coverage: Tracking Walking Floods

“…Remarkably, the lowest displacement ( d ext and d tot < 0.3) was characteristic of most of the boreal belt, especially across northern North America, Europe, and the vast majority of Russia. Local inundation dynamics were well captured at the landscape level with an approximate concentric expansion and retraction dynamic, possibly explained by the temperature‐dominated (as opposed to precipitation‐dominated) timing of floods (Kireeva et al., 2020; Papa et al., 2008; Torre Zaffaroni, Baldi, et al., 2023), the glacial processes that have shaped the topography of these landscapes in the past (i.e., a currently inactive geomorphological agent), and the role of permafrost in channeling water (Blöschl et al., 2020; Buttle et al., 2016; Rowland et al., 2023). It is crucial to note that these regions, due to the observed and potential effects of climate change on permafrost stocks (Holgerson & Raymond, 2016; Schuur et al., 2015; Smith et al., 2022), may face increased rates of displacement and geomorphological alterations, putting at risk local and downstream communities and ecosystems (Lafrenière & Lamoureux, 2019).…”