河床表層の鉛直構造の変動を考慮した付着藻類現存量の変動予測

Abstract

Supplying sediment below dams may change algal biomass on stone surfaces by not only promoting detaching algae but also decreasing exposed stone surface area for algae growth. This study is aiming to predict the algal biomass per unit area. Attached algae growth and detaching rate were measured in the prototype flume to make a prediction model focusing sand height and algal biomass. We also developed a new model to estimate the average height of exposed stones and their distribution. The result showed that the production rate was higher after sediment supply. Especially, the highest rate was recorded in case that the sand height was the just before the stone surface area start to decrease by sediment covering. If sediment will not reduce exposed area, higher production rate can be expected under the increasing sediment supply condition. The estimation of the exposed height or the riverbed covered degree should contribute to evaluate the effects of sediment supply on the habitat of attached algae.