Probabilistic models of extreme flood water discharges in the rivers of Cisbaikalia
N.V. OSIPOVA1, M.V. BOLGOV1, N.V. KICHIGINA2
1Institute of Water Problems of the Russian Academy of Sciences, Moscow, Russia
2V.B. Sochava Institute of Geography, Siberian Branch, Russian Academy of Sciences, Irkutsk, Russia
Keywords: maximum flood runoff, truncation of distributions, joint analysis, zoning, extreme hydrological events, integrated approach
Abstract
This article considers the possibility of using probabilistic models to analyze the maximum flow discharges of rivers in order to obtain reliable calculated statistical characteristics for hydrologically poorly studied basins. The study was carried out by using Cisbaikalia as an example, which is characterized by a flood regime of river flow. It was found that floods in the study area most often occur in the summer (July-August), which is associated with the climatic characteristics of the region, and are often destructive. The analysis of the maximum flow of rivers is based on data from the Roshydromet observation network. The series of maximum water discharges were checked for homogeneity and, in general, no disturbances in the steady state of runoff caused by climate changes were detected. As the main probabilistic model, a generalized distribution of extremes is proposed, the parameters of which are recommended to be determined on the basis of group analysis. For the first time, an integrated approach has been applied, which combines well-known methods of hydrological calculations that are most often used to clarify the characteristics obtained for the runoff in the zone of extreme values, namely: the apparatus for truncation of distributions, joint analysis of data, use of a reduction formula with reduction of the drain modulus value not only to the area of 200 km2, but also to the average height of basins in the region, as well as the method of probability of probabilities for estimation of obtained results. These methods are all recommended by regulatory documents for effluent calculations and are most often used separately. The comprehensive approach described by the authors makes it possible to take into account the features of the formation of runoff in the zone of extreme values and obtain more accurate values of characteristic quantiles of a given probability of excess for use in design on poorly studied rivers of the region.
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