Are Torrent Check-Dams Potential Debris-Flow Sources?

Check dams as a typical torrent structure behave as retention structures typically storing torrent sediments in order to stabilise the torrential bed. If such structures are damaged and partially broke down, stored torrent sediments may cause sediment-related disasters in the downstream torrent's reaches or on torrential fans. A field study on the status of 22 check dams in the Upper Sava River in NW Slovenia with regard to their structural stability was performed to answer a question whether they should be taken as a possible debris-flow source. For this purpose we used the existing inventory (cadastre) of water infrastructure in torrents and field survey. The resulted hazard assessment showed rather high debris-flow risk for downstream infrastructure in the lower parts of the investigated torrential watersheds. That is why we should treat some check dams as "large" dams.