Dynamic-Stochastic Model of Snowmelt Runoff Generation and Its Application for Estimating Extreme Floods

A coupling of a physically based model of snowmelt runoff generation with the Monte-Carlo simulation of the model inputs is applied. The model of runoff generation is based on the finiteelement schematization of river basin and includes the description of the following hydrological processes: snow cover formation and snowmelt, freezing and thawing of soil, vertical soil moisture transfer and infiltration, overland and channel flow. The Monte-Carlo simulation is based on stochastic models of daily precipitation series, daily air temperature and daily air humidity deficit (for continuous modeling during autumn-winter-spring seasons) or distributions of snow water equivalent, depth of frozen soil, and soil moisture content before snowmelt ( for modeling during only spring period). The dynamic-stochastic model was applied for the Seim River basin (the catchment area is 7460 km). The 20-years hydrometeorological measurement series have been used for calibration and verification of the dynamic part of the model (5 parameters have been calibrated); the 34-years series have been used for construction of the stochastic part. The calculated exceedance probabilities of the peak discharge were compared with ones calculated using 61-years runoff data. The good correspondence of the measured and calculated values have been obtained.