In this study, we investigated groundwater flow and its effects on the enhancement of water purification in a tidal flat located in the Ota River Floodway where a tide pool forms in the flood channel. It was found that groundwater flow from the flood channel maintained the groundwater level in the tidal flat, which contributes to both the relaxation of annual range groundwater temperature and the purification of groundwater quality. It is expected that, in the case that a low-water channel tidal flat forms in the river having compound structure, the nitrification and denitrification of sediment in the tidal flat are facilitated by constructing river structure to generate groundwater flow.
