Author(s): Tatjana Edler; Marcel Van Der Perk; Hans Middelkoop

Linked Author(s): Tatjana Edler, Hans Middelkoop

Keywords: Sediment; Rhine; Budget

Abstract: Suspended sediment is an important part of healthy river systems as it is a source of nutrients in soils of riverbanks and floodplains and eventually forms the principal building material of river deltas. Sufficient sediment is required for the delta to sustain area and elevation. In the past decades, the delivery of suspended sediment from many river basins to deltas has been decreased, which, together with sediment extraction through dredging and mining has caused the sediment budget in these deltas to become negative. To design strategies to attenuate or reverse the decreased sediment delivery, a quantitative understanding of the sources, fluxes, and budget of suspended sediment in river basins is crucial. The aim of this study is to quantify annual loads and budgets of suspended sediments in in the Rhine river basin during the past decades. For this, we used fortnightly or monthly measurements of suspended sediment concentrations at 34 monitoring and corresponding daily discharge measurements stations along the main branch of the Rhine river and its four major tributaries Aare, Neckar, Main, Mosel in the period 1990 – 2015. Annual suspended sediment loads were estimated by means of the sediment rating curve method, which allowed establishing the annual sediment budgets for the 28 river sections . Our results indicate that the annual suspended sediment load has decreased in nearly all river sections, including those in the tributaries, which has resulted in an overall decline of sediment delivery to the delta. This consistent decline of suspended sediment loads across the river basins suggests that its primary cause must be sought in basin-wide changes in land use, land management, hydrology, or climate. The precise cause of such changes needs further investigation.

DOI: https://doi.org/10.3850/IAHR-39WC252171192022984

Year: 2022