Estimation of the Probable Maximum Rainfall and Snowmelt Floods Via Physically Based Model of River Runoff Generation

by L. S. Kuchment,



Document Type: Proceeding Paper

Part of: North American Water and Environment Congress & Destructive Water

Abstract:

Disastrous floods can be caused by unusual combinations of hydrometeorological factors and river basin conditions that have not been observed during a long observation period. The physically-based models of runoff generation provides opportunities to find dangerous combinations of hydrometeorological factors and to estimate the risk of extreme floods. The case studies for a number of the Russian rivers have shown that although the probable maximum precipitation rate is usually larger then the probable maximum snowmelt rate, the maximum floods of the middle and large rivers of Russian are of snowmelt origin. The comparison of the calculated maximum snowmelt and rainfall discharges have been carried out. It has been revealed that at the same region the probable maximum discharge can be of snowmelt or rainfall origin depending on the river basin area and the runoff generation mechanism. The problem of the assignment of the extreme meteorological inputs is discussed. The methods of determination of the probable maximum snowmelt rate based on the heat balance approach are suggested. The reduction of the maximum snowmelt rate as a function of the basin area have been investigated. The estimates of the probable maximum discharges, obtained on the basis of application of physically based models, were compared with those computed by statistical methods.

Subject Headings: Snowmelt | Rivers and streams | Floods | Runoff | Basins | Hydrometeorology | Water discharge

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