CHANGING OF TWO-WAY RIVER COURSES IN RESTORATION PROJECT AT THE SHIBETSU RIVER

The Shibetsu River originally had a number of meander bends, and wetland spread in its lower reaches. Cut-off works to straighten the meandering river course began in 1953. As a result, safety level against flooding was much improved, the wetland disappeared and farmland development progressed in the river basin. In recent years, however, there have been increasing demands from local resident for creation of a river environment taking into consideration. Restoration of the natural river environment has therefore been promoted since 2000. Because it was considered difficult to ensure safety against flooding if only the old meandering river course was restored, it was decided to adopt a method of restoring the old river while maintaining the present straightened river course. Water was reflowed into the restored meandering river course on the March 18 2002. The conditions of the straight river course and the restored meandering course connected to it in the five months after reintroduction of water were observed.