Author(s): Sophia Demmel; Ludovico Agostini; Jessica Droujko; Peter Molnar

Linked Author(s):

Keywords: Suspended sediment; Monitoring; Experimental floods; Sediment yields

Abstract: Experimental floods (e-floods) are typically released in regulated rivers to simulate natural flood pulses and improve the ecological integrity of degraded reaches, for example downstream of dams. Here we show that it is very important to continuously measure the suspended sediment concentrations (SSC) during such e-floods so that released sediment volumes may be estimated and peaks of SSC which may have negative ecological consequences may be detected. The paper reports on the e-flood regime of the past 6 floods in the Spöl River, which has the longest systematic annual e-flood release program in Switzerland. We observe that (a) SSC waves typically show an early peak on the rising limb of the release hydrograph followed by subsequent smaller variations; (b) SSC peaks often exceed 5 g/l which is considered a critical level for fish; and (c) despite almost identical discharge peaks, the total released fine sediment yields during e-floods varied from ~1000 to 2,500 tons, indicating that the availability of sediment for transport plays an important role. With this work we argue for a consistent high-resolution monitoring of SSC during e-flood releases for ecological purposes.

DOI: https://doi.org/10.64697/iahr.proc.ise2026.abs.318

Year: 2026