2025 Volume 35 Issue 1 Pages 55-66
This report describes the results of an environmental monitoring study and the development of a sediment supply test downstream of a multi-purpose dam located in the Yoro River, Chiba Prefecture, which is a sand-bed river, that has been conducted for about 10 years. The annual sediment supply volume was increased from 1,500 m3 to 10,000 m3 by reviewing the timing, frequency, shape, etc. of sediment placement in the river channel. In monitoring surveys, various surveys were continuously conducted in the downstream river, and no particular impact was observed. On the other hand, it was confirmed that the proportion of fish species that prefer sand beds tended to increase with the expansion of the distribution range of sand content.
