Sediment build-up in valleys could lead to catastrophic floods downstream.
Researchers studied sediment movement in the Dragonja catchment in Slovenia. They found that sheet wash on agricultural fields was the main source of sediment, with bank erosion and channel incision also contributing. The river carries most sediment during high-flow events, depositing some on floodplains. Sediment disintegrates during transport, leading to a build-up in the valleys. Extreme floods can flush stored sediment downstream.