| The original appearance of the Shibetsu River、 Hokkaido、 included numerous repeated meanders、 with the lower reaches flowing through a broad、 undeveloped helocrene. After 1953、 full-scale cutoff works were completed to straighten the meandering river channel and lower the levels of groundwater and the river、 to increase land use in the river basin and improve flood safety. As a result、 flood safety improved and the helocrene vanished as the groundwater level fell、 and the river basin was developed into farmland. Over time、 however、 local demands to recreate the river’s natural ecosystem increased. Since 2000、 an effort has been made to restore the meandering river channel through "nature restoration-type river development".Before beginning full-scale meander restoration、 a test flow using part of the former river channel (an oxbow lake) was created to understand and solve technical problems caused by meander restoration、 by restoring the former river channel while retaining the present straightened channel. On March 18、 2002、 water flow was released into the former meandering river channel. In this paper、 we report on a study we conducted concerning changes in the straight channel and the former river channel to which it was connected、 after commencement of the water flow. |
