SNOWMELT FLOOD FREQUENCY ESTIMATION USING PHYSICALLY BASED MODEL COUPLED WITH WEATHER GENERATOR (WITH ESTIMATION'S UNCERTAINTY)

摘要

A dynamic-stochastic model, which combines a physically based model of snowmelt runoff formation with a stochastic weather generator, has been proposed to estimate frequencies of extreme snowmelt floods. The physically based model describes snow accumulation and melt, soil freezing and thawing, vertical soil moisture transfer and infiltration, detention of melt water by the depressions at the catchment surface, overland and channel flow. The weather generator includes stochastic models that produce daily values of precipitation, air temperature, and air humidity during a whole year. Daily weather variables have been generated by Monte Carlo procedure and transposed to snowmelt flood discharges by the physically based model. The suitability of the dynamic-stochastic model has been demonstrated through its ability to reproduce frequencies of snowmelt flood peak discharges measured at the Seim river (the catchment area is 7460 km~2). Uncertainty of the calculated peak discharges of low probabilities has been assessed on the basis of Latin hypercube sampling.