Evaluation of gravel and sand found on stream preservation works
of Neo]Natural River Reconstruction Method after the improvement
Ken]ichi UMEZU and Osamu TOMATSU
Abstract
Flood control and water utilization have been considered as important factors
in river works for some time now. However, in recent years, there is an emphasis
on the Neo]Natural River Reconstruction Method which takes into account the biological
environment of the river. The Ministry of Construction has been promoting this
method since 1990, and has implemented it in the whole country. This Neo]Natural
River Reconstruction Method recognize the biological environment and preserve
a natural landscape. Therefore, it is possible to evaluate the method by observing
the process of environment recovery after the structure is completed. Unfortunately,
there have been no studies to observe this environment recovery process after
the completion of the structure. Therefore, we had observed characteristic of
gravel in each different riverbed condition point in natural riverbeds, and artificial
riverbeds. As a result, we have concluded that this filed has various distribution
of riverbeds gravel than natural riverbed, and total displacement length of gravel
tracer was within 300 cm when high water level at May in 2006. In this paper,
we describe evaluation of riverbeds gravel in stream preservation works of Neo]Natural
River Reconstruction Method in Gifu prefecture.