Home – Home – Jornals – Geography and Natural Resources 2024 number 3

The results from studying the specifics of the formation of rain floods in river basins of mountainous areas are presented. The features in the formation of dangerous hydrological events, such as floods and mudflows, are considered. An analysis of the rain floods characteristics on the rivers of the Eastern Sayan mountains was carried out, based on data from highly detailed monitoring of river flow parameters and atmospheric precipitation using automatic measuring devices. Water level measurements are carried out once every 15/30 minutes, and precipitation once per hour. The characteristics of floods for the flood season of 2022 on eight rivers are given as well as floods on the Belaya and Kyngarga Rivers from 2019 to 2022. For extreme floods that can cause significant damage, an assessment of flood-forming precipitation is made. The timing of passage, duration, height of the level rise and its amplitude, the rate of rise and fall, etc. are determined. It was established that during flood season, up to 10 rain floods of different sizes occurred on the rivers. There is a synchronicity in the high floods passage on the left tributaries of the Angara river. Most often, the maximum floods of the year occurred in July. The duration of a flood rise is on average 2-3 times less than its reduction, and the average rate of level rise is three times higher than the rate of reduction. The duration of the highest levels during floods is several hours. For small floods occurring in mid-summer, it is 15-30 minutes and is equal to the measurement step of the devices. Flood-forming precipitation during extreme floods can be long-lasting and widespread or intense and short-lived. The total amount of precipitation before the peak of the flood varied from 31,4 to 122,6 mm, and the average intensity of precipitation varied from 0,10 to 1,95 mm/h.