An ex‐post analysis of the German Upper Rhine: data gathering and numerical modelling of morphological changes in the 19th century

Abstract

AbstractTo ensure sustainability, long‐term effectiveness and limited maintenance, river flood management practices should take into consideration the potential morphological adaptations resulting from the imposed changes to a river system. To illustrate the ability of numerical models to provide a valuable tool for flood management planners, an ex‐post analysis of the Rhine during the 19th century is carried out. The Upper German Rhine has been reshaped deeply by large engineering works over this century. The initially braided reach Basel–Maxau was constricted into a single channel, while the reach Maxau–Mainz was significantly shortened by meander shortcuts. Both types of works resulted in intense erosion upstream and spread deposition downstream, with most of the changes occurring during high‐flow periods. As ancient data are generally difficult to obtain, the paper shows how fragmentary ancient data may be complemented with more recent data adequately interpreted for reconstructing a realistic set of initial conditions. The study is an attempt at reproducing qualitatively the behaviour of the Upper Rhine with a dataset collected only from publicly available sources.