2004 Volume 48 Pages 991-996
In the Kita River, several large-scale widening of low channel have been carried out from 1998 to 2003. To understand the impact of the widening on river ecosystem, field surveys are conducted at two investigation sites: Honmura and Matono districts. At Honmura district, where the widening of low channel has been carried out before 1982, variation of riverbed, plane distribution of vegetation and the thickness of surface soil layer were investigated. On the other hand, the sedimentation structure of the flood channel which have been formed in several hundreds years was surveyed at Matono District. It is inferred from these results that there would occur the extension of wetland covered with willow and phragmites community and the reduction of bare bars in the future after the widening of low channel in the Kita River.
