Optimierung der Klauswehrordnung des Mondsees, Teil I – Hydraulik

The main objective of this paper is to quantify the discharge capacity and potenzial of the outlet system at Lake Mondsee, Austria. The results obtained here are used as a hydraulic basis in optimizing lake control and in defining the technical scope for actions to improve flood risk management. Using a hybrid modelling approach consisting of numerical and physical modelling as well as field measurements for calibration and validation, it was shown that the existing hydraulic conditions have a discharge limiting effect resulting in high lake water levels during floods. The reduced hydraulic capacity of the lake outlet system both limits the current lake operation and the possibility for future optimization. A notable increase in discharge is achievable by enlarging the effective flow cross-section, reducing the flow resistance of the weir inlet channel and adjusting the flap position at the weir. The hydraulic analyses were accompanied by a stakeholder survey, from which limitations and user-specific criteria for revising lake control at Klauswehr could be derived. The inclusion of stakeholder interests was considered a decisive step towards a generally acceptable and thus feasible optimized lake control for improved flood risk management at Lake Mondsee.