抄録
There are many small debris flow torrents so called zero-order basins. It is usual that a channel with necessary cross section can not be prepared at downstream of a sabo dam. The frequency of debris flow is low, for example once every 100 years. Debris flow control can be said a sort of crisis management. To control not whole debris flow but only sediment is a rational way. Damage by only water must be accepted to some extent. Present control structures are strong but expensive. The budget for debris flow hazard mitigation has been shrinking. A simple structure, we call a debris flow fence is proposed. It is made of steel not of concrete. It is less expensive and can be constructed for a few months.
