HYDROLOGICAL MODELLING OF SMALL ALPINE WATERSHEDS WITH THE NAM MODEL

Analysis of long-term hydrometeorological data in the Alps shows an increasing number of rainfall and flood related natural hazards. Beside decreasing return periods of high-flow events, the intensity of hydro-meteorological disasters has been increasing. Weather risks of this type may result in higher material and economic losses, thus prevention and protection from floods becomes a major challenge, where forecasting has an indisputable role. A great number of hydrological models are now available with a wide range of data requirement and usability. The aim of this paper is to verify the applicability of the MIKE 11 rainfall-runoff model on the watershed of Lake Mondsee, a small Alpine catchment located in Salzkammergut, Austria. The NAM (Nedbor-Afstromnings-Model) is a lumped and conceptual model with an autocalibration algorithm providing a timesaving option for the adjustment of the great number of free variables included in the system. The simulated runoff and long-term accumulated runoff results of the modelling achieved a variance above 86% with a proper model structure, matching the characteristics of the studied watershed, and a set of parameters provided by a systematic calibration-validation process focusing step-by-step on low flow, high flow parts of the runoff and on the overall RMSE. The model proved to be applicable to the Mondsee catchment and is expected to work in similar catchments as well, and could serve as a useful tool for runoff estimation on unmonitored catchments.