2024 Volume 80 Issue 17 Article ID: 24-17140
The mouth of the Sekikawa River, which flows into the Sea of Japan, opens predominantly in the NNW direction, where winter high waves prevail. Consequently, during the winter season, high waves can propagate upstream in the river channel, leading to sediment deposition from the mouth of the river to approximately 1.6 km upstream on the left bank of the Sekikawa River. Previous studies have reported that sedimentation was facilitated by long-period waves. In this study, first, we analyzed data such as aerial photographs, topographic surveys, and river flow rates to understand the geomorphic characteristics formed by river flow. We revealed the formation of a sandbar near 0.7 km upstream. Next, to elucidate the factors influencing sediment deposition from the mouth to 0.7 km upstream, we conducted wave and flow observations within the river channel and topographic surveys during the winter high wave period. It was found that sediment within the river channel from the mouth to approximately 0.4 km upstream primarily moves and deposits due to wind waves, while upstream from 0.4 km, there is potential for sediment transport during the propagation of long-period waves.
