3:45 PM - 4:00 PM
[MAG41-08] Change of sediment sources in suspended sediments due to surface decontamination in the Niida river catchment area affected by the Fukushima Daiichi nuclear power plant accident
Keywords:Cs-137, suspended sediment, Niida river, Decontamination works
In the Niida river basin, we installed an integrated suspended sediment sampler, turbidity sensor, and water level sensor at the downstream site starting in December 2012, and another three sites, Sakegawa-bashi (SK), Notegami-Kita (NT) and Warabi-daira (WR) in July 2014. The monitoring has been continued until now. During our monitoring period, most of the agricultural land (paddy and cropland), the topsoil up to 5 cm and replaced with lower part of the soil taken from 2014 to 2015.
We found that the flux of suspended sediments has increased with executing rate escalation of decontamination activity. Also after the decontamination activities, the number of counterclockwise hystereses increased compared with other types. In this presentation, we will discuss the effect of decontamination on the fine sediment yield to the downstream, and the use of radiocesium as a tracer of suspendiment sediment sources.