From the Rio Rotiano to the regional scale: Identifying and managing protection structures at risk

Since the second half of the 19th century, many protection works (mostly check dams) have been built on mountain channels of the Alps. The general objectives of control works are to avoid the loss of agricultural and forested areas due to channel erosion and slope destabilization and to defend settlements and transport routes. Over time, the former function became less relevant, while the latter became largely prevailing. Some issues arose in recent years: - Many check dams are reaching the end of their lifespan. - In some cases, the current protection needs are different from those at the time when the protection structures were built. - In the worst cases, the failure of check dams may enhance the severity of floods and debris flows, as happened in the Rio Rotiano. An index was developed for preliminary identification of "critical" check dams prone to failure, or whose failure could have major impacts (large sediment volumes involved, cascading effects). The index is intended to be: - suitable for application at regional scale - simple and taking advantage of already available information - aimed at defining priorities for monitoring (i.e. orienting more detailed analysis).