Катастрофические паводки в бассейне Ангары в 2019 ГОДУ: моделирование условий формирования и водного режима рек

Abstract

The main factors of extraordinary rainfall floods formation on the Angara River left tributaries in the summer of 2019, which caused catastrophic floods in the Irkutsk oblast, were investigated. On the basis of information modeling system, the core of which is a physically based model of runoff formation ECOMAG, a spatial distributed regional hydrological model was developed. The model performance was evaluated against the longterm (35 years) data of hydrometeorological observations in the five river basins of the region. It was found that the simulated stream flow hydrographs and the peak flow values fit satisfactorily (in terms of the assigned statistical criteria) to the corresponding observations. Based on the spatial modeling results, fields of the hydrological cycle characteristics (precipitation, snow water equivalent, soil moisture) in the upper Angara basin in the summer of 2019 were analyzed. It was shown that the main factors in the formation of catastrophic floods on the Iya River were extreme precipitation combined with small losses of runoff for infiltration into preliminary saturated soils. The simulated peak flow discharge on the river near city of Tulun exceeded the historical maximum by 40% and amounted to 5640 m 3 /s. The spatial and temporal peculiarities of the two flood waves formation on the studied Angara River left tributaries in 2019 were analyzed.