Author(s): Sohei Kobayashi; Boyuan Cai; Sameh Kantoush

Linked Author(s): SAMEH KANTOUSH

Keywords: Channel incision; Bed stability; Armouring; Sediment replenishment; Shield'sparameter; Benthic invertebrates; Caddisflies

Abstract: Channel incision and riverbed armoring caused by sediment deficit can lead to serious environmental issues, including outbreaks of certain organisms and the loss of species diversity in rivers. The changes in cross- sectional shape, flood-flow characteristics, and riverbed stability for benthic invertebrates, as well as the current spatial distribution of these organisms, were examined in the Uji River, Kyoto, Japan. Although the upstream dam was constructed about 60 years ago, channel incision and riverbed armoring have still been progressing over the past 20 years, as indicated by changes in cross sections, bed grain size, the Shields parameter, and water level. Benthic communities were dominated by net-spinning caddisflies, sessile clams, and less-mobile snails, all of which prefer stable bed conditions. Caddisflies were more abundant in riffles, whereas clams and snails were more abundant in runs and pools within sites, and all groups were more abundant at sites with higher bed stability. Sediment replenishment with appropriate grain size and volume can improve riverbed conditions and reduce caddisfly abundance to an appropriate level by enhancing the riverbed mobility and disturbance necessary for maintaining species diversity.

DOI: https://doi.org/10.64697/iahr.proc.ise2026.abs.137

Year: 2026