Numerical modelling of bank failures during reservoir draw-down

¹ Department of Civil and Environmental Engineering, The Norwegian University of Science and Technology, S. P. Andersens vei 5, N-7491 Trondheim, Norway
² Department of Hydraulic Engineering and Water Resources Management, University of Stuttgart, Pfaffenwaldring 61, D-70569 Stuttgart, Germany

^* Corresponding author: nils.r.olsen@ntnu.no

Abstract

Numerical algorithms are presented for modeling bank failures during reservoir flushing. The algorithms are based on geotechnical theory and the limit equilibrium approach to find the location and the depth of the slides. The actual movements of the slides are based on the solution of the Navier-Stokes equations for laminar flow with high viscosity. The models are implemented in the SSIIM computer program, which also can be used for modelling erosion of sediments from reservoirs. The bank failure algorithms are tested on the Bodendorf hydropower reservoir in Austria. Comparisons with measurements show that the resulting slides were in the same order of magnitude as the observed ones. However, some scatter on the locations were observed. The algorithms were stable for thick sediment layers, but instabilities were observed for thin sediment layers.