MODELING OF THE SUMMER 2019 DISASTROUS FLOODS ON THE IYA RIVER (IRKUTSK OBLAST)
O.M. MAKARIEVA1, N.V. NESTEROVA1, A.D. FEDOROVA2, A.N. SHIKHOV3, T.A. VINOGRADOVA2,4
1North-East Research Permafrost Station of Melnikov Permafrost Institute, Siberian Branch, Russian Academy of Sciences, 685000, Magadan, ul. Portovaya, 16, Russia
omakarieva@gmail.com
2St. Petersburg State University, 199034, St. Petersburg, Universitetskaya naberezhnaya, 7-9, Russia
alexandra120559@gmail.com
3Perm State National Research University, 614068, Perm, ul. Bukireva, 15, Russia
and3131@inbox.ru
4OJSC SPA Gidrotekhproekt, 199178, St. Petersburg, Chetyrnadtsataya liniya Vasilyevskogo ostrova, 97, lit. А, pom. 3-N, Russia
vinograd1950@mail.ru
Keywords: catastrophic flood, Hydrograph hydrological model, maximum water discharge, ICON weather model, extreme precipitation, streamflow hydrographs
Abstract
The paper discusses the results of investigation of the factors that led to the formation of a catastrophic flood in June 2019 on the Iya river in Tulun town, Irkutsk oblast, as well as a calculation and assessment of the characteristics of these floods. Ananalysis of the meteorological environments of flood formation is performed by using the ICON global weather forecast model. The trends in hydrometeorological characteristics for the period 1966-2019 are analyzed. The study revealed an increase in the precipitation amount in June by 36-61 % (31-46 mm), and negative trends in the maximum water discharges making up 24-37 % from May to September. Using the data on the water level and historical Q(H) curves, the maximum daily water discharge on June 29, 2019 was estimated at 6800 ± 700 m3/s. A schematization of the Iya river basin is carried out, the pa-rameters are systematized and the distributed hydrological model Hydrograph is verified. For three sub-basins within the Iya river basin, the median value of the Nash-Sutcliff criterion was 0.69 for the period 1970-1996. The flood characteristics are simulated and assessed using two sources of meteorological data. According to the data from weather stations, the maximum daily discharge was 6570 m3/s. This value falls within the range of estimates of observed values but its formation is delayed by 1 day. According to the simulation based on the ICON model data, the maximum 3-hour discharge reached 5260 m3/s, or at least 840 m3/s lower than the observed value; however, the simulated flood hydrograph coincides with observed one for the time intervals. The results of the study confirm a possibility for a short-term flood forecast using the method of deterministic hydro-logical modelling
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