Hydroclimatic features of mud flood formation in the Slyudyansky district of Irkutsk oblast
N.V. KICHIGINA1, A.A. RYBCHENKO1,2, A.A. YURYEV1,2
1V.B. Sochava Institute of Geography, Siberian Branch, Russian Academy of Sciences, Irkutsk, Russia
2Institute of the Earth’s Crust, Siberian Branch, Russian Academy of Sciences, Irkutsk, Russia
Keywords: mudflows, rainfall floods, flood-forming precipitation, water level, mountain rivers, Slyudyansky district
Abstract
The main hydroclimatic factors of rainfall and mud flood formation have been studied, and the spatial distribution of flood hazard of various genesis has been determined within the territory of the Slyudyansky district of Irkutsk oblast. The maximum water levels at six hydroposts of the Roshydromet network for 2001-2022 have been analyzed. All flood cases with the excess of critical levels corresponding to the onset of flooding have been identified. Flood-forming precipitation and atmospheric circulation features have been assessed for years with floods. It has been determined that the greatest danger is posed by rainfall and mud floods in the Khamar-Daban estuary zone. Mudflow processes are most developed here, and the towns of Slyudyanka and Baikalsk, as well as the sludge storage facilities of the closed Baikal Pulp and Paper Mill, are at risk. In the 2001-2022 period, floods were recorded at three hydroposts in 2001, 2005 and 2019. The floods in 2001 and 2019 were of rainfall genesis, and in 2005 - mixed snow and rain. Extreme precipitation (up to 200 mm per day or more, according to the Khamar-Daban weather station), along with previous humidification of the territory during the meridional circulation of the atmosphere, are the main factors in the formation of rainfall floods and mudflows here. Foothill weather stations reflect the climate of only the coastal strip. The most representative data for a significant part of the river basins are the data of the high-mountain (1442 m above sea level) Khamar-Daban weather station, where almost twice as much precipitation falls as in the foothill territory. This difference in the amount of precipitation is not taken into account when analyzing observation data from weather stations located in the foothill territories. Therefore, for mountain catchments, it is important to create an observation network in high-mountain areas where rain floods and mudflows are formed, especially where settlements are located in the foothills.
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