2018 年 24 巻 p. 343-348
Exposure height of stones — the maximum height from the riverbed surface to the top of stones — was proposed as an indicator for quantification of burial degree of stones then applied to an assessment of changes in riverbed environment after an artificial sediment supply in the Yahagi River using the BACI (Before-After-Control-Impact) design. As interaction between time (before and after) and sites (control and impact) was not significant, the effects of the artificial sediment supply were not detected in this study. The results should be caused by the used fine sediments (particle size at 50% percentage passing: 0.2 mm), which were expected to be little deposited. Trends of decrease in exposure height in the both control and impact sites may be caused by deposition of fine sediments associated with natural flow regimes because trends of increase in coverage of smaller size classifications (less than or equal to gravel) on the riverbeds were observed in the both sites. Therefore, the exposure height of stones should relate to fine sediment deposition. Effectiveness of the exposure height of stones for evaluation of changes in riverbed environment should be examined in the future studies aimed to artificial sediment supply using coarser sediments which are expected to be deposited on riverbed.
