**Abstract Text**
Remote sensing technique has enabled to depict the turbidity distribution not only at limited observation points but also throughout watersheds. In this study, turbidity maps were processed based on NIR bands’ information from Sentinel-2 (10 m resolution) and Planet Dove (3 m resolution). They were used to investigate the turbidity distribution in spatiotemporal manner in the Iwaki River basin (Japan).
The basin has experienced a significant flood in August 2022 with minor slope collapse in the upstream mountain area. After the flood, the basin has been experiencing high turbid condition in months. Field observation found that the differences of high turbidity in main stream and low in sub streams. The authors attempted to elucidate the differences by focusing on the geological structures and rainfall distribution. The satellite information, field surveys, and rainfall-runoff-sediment-transport model were used to explain the differences. 
The satellite information showed that the turbidity of the main stream remained at around 200 FTU for a long period over a wide area. In contrast, the turbidity of sub streams temporarily increased up to about 50 FTU, then decreased to below 10 FTU in a few days. Field surveys revealed that these differences were due to differences in geological structures; the one could produce the silt and the other produce the sand, in the upstream mountain area. In fact, very fine sediment about 100 μm was remained in higher turbid river sections, however, only fine sediment about 1 mm was observed in lower sections. The rainfall-runoff-sediment-transport model yielded similar results.



Turbidity monitoring using satellite information in a river with complex geological structures – case study in the Iwaki River basin, Japan (Room 322, June 26th, 3:30pm-5:00pm)

Engineers, researchers, and climate scientists share developments and innovative practices in the water engineering industry. The Technical Committee for Hydraulics Measurements and Experimental Methods (TCHMEM) of EWRI has organized the HMEM conference six times since 1994, when the first HMEM conference was held in Buffalo, NY. Since then, successful conferences were held in Estes Park, Colorado (2002), Lake Placid, New York (2007), Snowbird, Utah (2012), and Durham, New Hampshire (2017).