Home – Home – Jornals – Geography and Natural Resources 2020 number 4

Based on operational data from the Irkutsk Hydrometeorological Service, the main characteristics of catastrophic flood that occurred in the period from June 24 to July 13, 2019 on the rivers of the Iya drainage basin are presented. It is shown that the flood on the Iya river and on its tributaries was the highest both in the runoff volume and in the maximum water discharge for the entire observation period. Contribution from the various parts of the Iya catchment to the total flood runoff is considered. An increased variance in fluctuations of the maximum water discharges since 1980 and increased repeatability of very large values of discharges over the last several decades were determined. This is a reason for the heterogeneity of the maximum water dis charges for a long observation period. Standard distribution curves did not allow to adequately describing the empirical points on the probability curve. Only based on combined use of composite homo generous distributions and consideration of the out standing rare maximum it became possible to obtain a satisfactory compliance between empirical and analytical distributions of maximum water flow rates and determine calculated parameters of the maximum discharges the Iya river near the city Tulun. Estimation of the calculated maximum water disharge and depths of flood runoff of different probability in the post the Iya river - Tulun city are presented.