Author(s): S. M. Sayah; S. Mai; J.-L. Boillat; A. J. Schleiss
Linked Author(s): Anton J. Schleiss
Keywords: In situ measurements; Wind and wave prediction; Numerical wave modelling
Abstract: Large lakes in Switzerland, as many other lakes in Europe, suffer from severe beach erosion. In order to thwart the continual regression of shores, systematic analysis of the effect of wind waves on natural shores is undertaken. The analysis allows a better and comprehensive understanding of the impact of waves on the surf zone, generated during mean as well as extreme wind events. It provides a helpful tool for the design of shore protection measures in Swiss lakes. The research is carried out at Lake Biel. It comprises field measurements of wind and waves, and includes furthermore, numerical simulations of wind- waves. In a first stage, a large-scale phase averaging wave model is set-up. This allows predicting the wind generated surface wave climate in Lake Biel and the impact of incident waves on the eroding shores. The simulation is based on in-situ measurements of wind over land and water, in addition to wave characteristics. The results are compiled in a wave atlas relating wind conditions (speed and direction) and wave conditions (significant wave height, mean period, mean wave direction). Using the transfer functions, wave statistics are determined based on wind statistics. For the calibration of the model, a transient calculation of the wave field is carried out using a time-series of winds, measured in December 2003, as the driving force. The quality of the model is proven when comparing its results with wave measurements. They can be used to analyze the effectiveness of different projected shore protection measures, e. g. brushwood fences or breakwaters.