2010 Volume 16 Pages 89-94
In the yosasa river, that a flood occurred by a heavy rain in the August, 1998, the large-scale improvement was performed. The authors observed the changes of the topography of the river-bed to examine a response by the impact of the construction.
As a result, I confirmed the following: 1) Sands and gravels began to flow from the river-bed, then accumulated in the wide place of the river and in the inside of the bend. 2) In several places, the gravels of the river-bed disappeared, and bedrock cropped out. 3) A plant grew in the place that water did not flow through, and the landscape of the river changed. 4) The change of the topography of the river-bed is slowly, because the amount of gravels and sands flowing from the upper basin is little.
