Author(s): Paul Demuth; Cristina Rachelly; David F. Vetsch; Robert M. Boes; Volker Weitbrecht

Linked Author(s): Paul Demuth, David Vetsch, Volker Weitbrecht, Cristina Rachelly, Robert Boes

Keywords: River restoration; River widening; Dynamic river widening; Excavated river widening

Abstract: Due to anthropogenic activities, many rivers in Switzerland and worldwide are highly degraded. Hence, they are limited in width, channelized, straightened, and the sediment budget is often strongly imbalanced due to sediment mining and damming, leading to sediment retention. Such rivers are characterized by decreased morphological heterogeneity and dynamics and substantial losses in riparian biodiversity. Based on regulations such as the EU Water Framework Directive 2000, many countries nowadays pursue river restoration strategies to mitigate these negative effects. Swiss river restoration efforts include re-establishing sediment continuity at hydropower plants and reach-scale restoration measures along 4'000 km of streams and rivers, among other targets. River widenings, varying in length from a few hundred meters up to several kilometers, are an oftenimplemented restoration measure. In this study, we investigated the layout of 105 existing and planned river widenings in Switzerland. The first widenings realized in Switzerland were fully excavated to immediately establish the design geometry. More recently, dynamic river widening has become popular, where bank protection is removed, and bank erosion can progress during morphologically relevant discharges. Most river widenings in Switzerland are one-sided, i. e., on one orographic bank only. 20% of the projects considered in this study involved widening on both sides of the river. The present paper gives an overview of the restoration progress by river widening in Switzerland and referring to a data set of the above-mentioned 105 widening projects including their most important characteristics.

DOI: https://doi.org/10.3850/978-90-833476-1-5_iahr40wc-p0562-cd

Year: 2023