A comprehensive characterization of the flood hazard on the rivers of the Baikal region is presented, which was obtained by investigating the streams within the basins of the Angara, Upper Lena (with...

We have estimated the rate of changes in the main hydroclimatic characteristics for the period 1961–2008. It has been established that all months are involved in the formation of positive tendencies of mean annual temperatures, with the largest changes corresponding to February (0.62–1.94°C/10 years). It has been found that the changes in annual precipitation amount and annual river runoff are differently directed and mostly statistically insignificant. The cold period of a year is dominated by tendencies for a decrease in the amount of precipitation. A predominance of positive changes in river runoff is observed between October and December.

Siberia is a huge and relatively sparsely populated territory in the centre of Eurasia with a harsh climate and diverse flow formation conditions. Nevertheless, it is characterized by a high flood hazard, as most of the settlements and industrial centres are located along river banks. The flood hazard can vary across space and time against a background of climatic and anthropogenic changes, as well as socio-economic factors. We carried out a geographical analysis of floods as a tool to identify the present status of flood hazard in Siberia. The analysis included: analysis of flood hazard during a period of climatic change (1985-2016); analysis of ice jams and ice dams as a specific natural factor causing floods; and identification of areas with different flood hazards using multi-scale mapping. Rainfall floods, mixed floods (due to rainfall and snowmelt) and floods resulting from ice dams are the most dangerous in Siberia. They have the highest rate of recurrence, strength of impact, and number of fatalities and displaced people. The locations of areas with different flood hazards were identified by multi-scale mapping. The highest flood hazard in Siberia is in the most populated and economically developed southern regions along the Ob, Lena, Yenisei rivers and in the Lake Baikal basin. In areas with a high flood hazard, complex measures are needed, taking into account regional peculiarities.

In June and July 2019, on the left tributaries of the Angara river there occurred catastrophic rainfall floods inflicting enormous damage and human victims. The greatest damage was experienced by the city of Tulun on the Iya river. A comprehensive characteristic is given to the 2019 floods in comparison with similar events of the historical past and from the period of instrumental observations. An analysis is made of the characteristics of the flood hazard at gauging stations: their frequency and impact. The homogeneity of the series of the peak flood runoff is estimated against the background of climate change. The objects for study were the basins of the left tributaries of Angara river: the Irkut, Kitoi, Belaya, Oka, Uda and Biryusa, with a more detailed characteristic for the Iya river basin. The floods of 2019 were formed by extreme precipitation on the previously moistened surface of the catchments. In 2019, an exceptional hydrological situation developed in terms of both flood hazard characteristics and the devastating consequences for the city of Tulun. Nevertheless, catastrophic floods of a similar magnitude also reoccurred in the historical past and during the period of instrumental observations. The situation with two extreme floods during the summer season is also not unique. The event under study cannot yet be associated with climate change. Changes in the peak rainfall runoff series are mostly insignificant, even when the approximate runoff maxima of 2019 are taken into account. The decreased flood frequency over a later period may be associated with a low-water period that ended in 2019. Therefore, similar events can be expected to recur on the rivers of Irkutsk oblast, both within the Angara basin and within the Lena and South Baikal basins.

We examine the water potential and the characteristics of the present state of Siberia’s water resources in the early 21^st century. The resources utilization and the ensuing problems are analyzed, and the ways to solve them are highlighted. The flood genesis, frequency and damage are investigated. The possibilities of exporting the Siberian water to neighboring countries are explored.