宮ヶ瀬ダムの放流試験による河川流下有機物の変化とその要因

抄録

This study aimed to estimate the effects of experimental flood on particulate organic matter in river water below the Mayagase Dam. We classified the POM into some origins by stable isotope analysis. Terrestrial plants, POM of the dam discharge water, and periphyton in three sections were assumed as sources of carbon and nitrogen of POM in the river. Periphyton in middle-section of our study area supplied much organic carbon and nitrogen to POM in the downstream of river. Periphyton drifted down by shearing stress of around 200g cm⁻¹ s⁻² or more. The plan of the discharge water of the dam to flush periphyton away should pay attention to the shearing stress value of 200 g cm⁻¹ s⁻². The frequency of the river water flux that can flush out the periphyton had decreased by the existence of the dam.