"If a man will begin with certainties, he shall end in doubts; but if he will be content to begin with doubts he shall end in certainties." (F. Bacon, 1605)
The goal of this research project is to develop a dam break analysis tool. An user friendly, numerically accurate and robust, and cost and time saving application shall be implemented. This application aims at supporting the decision makers in their risk assessment. Embedded in QGIS and BASEMENT, both existing software packages, the main focus of the project is on the quantification of the numerous uncertainties in dam break modeling. The origin of these uncertainties is the yet missing exact understanding of the progressive mechanisms of dam breaching, while this process being the most sensitive one regarding the flood inundation.
The uncertainty quantification will be accomplished by the use of meta-modeling, where simple approximations of the computationally intensive and physical based dam break models are at focus. In addition the strength of georeferenced data is utilized to include numerous spatial and socio-economical aspects in the post-processing, such as buildings, bridges, schools etc.
Peak discharge capping of floods at Langkampfen river power station
Lüke, Eva Martha Gerber, Marco Vetsch, David Boes, Robert
The construction of a run-of-river power plant may involve the separation of floodplains from the river. Consequently, the flood peak discharge will not be reduced due to inundation of the floodplains anymore and thus the flood wave will not be damped by retention. This may lead to more acute flooding problems downstream of the power plant, especially for people and buildings in densely populated regions.
The run-of-river power plant Langkampfen on the Tyrolean Inn, operated by TIWAG – Tiroler Wasserkraft AG, was built in 1998. Due to the construction of the weir and the embankments along the river, a reservoir has been formed. This artificial reservoir shall be used to reduce the flood peak discharge. The objective is to control the weir during the passage of the peak discharge to refill the storage and to facilitate an optimal capping. The volume of the instream reservoir is small relative to the flood volume of the Inn river, so that only peak discharge capping becomes possible. The potential retention volume depends on the discharge as well as the corresponding water level. The higher the discharge, the lower is the retention volume. Furthermore, a forecast of the flood hydrograph to be capped must be provided for optimal retention.
The flood routing and the control of the weir are simulated with a hydrodynamic 1-D model developed at VAW, namely BASEMENT. The model includes a PID (proportional integral derivative) controller that can be used for controlling the water level in the reservoir. The objective is to adapt the PID controller automatically to the situation before, during and after the flood event. Therefore, requirements for the controller regarding the gate operation during the passage of the flood wave must be predefined. For the capping operation, the main constraints are not to exceed the normal operation water level and to comply with the freeboard regulations. The model is tested by investigating past flood events and possible scenarios. Finally, the model will be implemented for real time operation to provide recommendation to the operator for weir control during a flood event.