Ahead of the curve : channel pattern formation of low-energy rivers

Many rivers have been channelized in large parts of the world in the past centuries. However, in the last decades, realization has grown that channelization has negative consequences: it results in loss of ecological niches and high discharge peaks that may lead to flooding. Therefore, rivers worldwide are currently being restored. One of the most used restoration measures in small, low-energy rivers is to re-meander the river channel pattern, often by mimicking the sinuous pattern from before channelization. However, it remains largely unknown how sinuous patterns of low-energy rivers naturally form and develop with time, because they do not have sufficient energy to erode their banks, and generally do not show lateral migration.

In this doctoral thesis, the aim is to understand and predict the channel pattern formation of low-energy rivers. Distinctive channel patterns form in valleys with a peaty, heterogeneous and sandy floodplain. For each river type, a palaeogeographic reconstruction was performed using coring, ground-penetrating radar and geochronological data from different valley cross-sectional research sites. Based on these reconstructions, conceptual models were developed on how these channel patterns develop. The bank strength was identified as a key forming factor of the channel pattern of low-energy rivers, and incorporated in a newly developed channel pattern prediction tool, which has a high prediction success. River restoration can benefit from the insights of this research and focus on restoring natural processes of low-energy rivers in a scientifically sound way.