Characteristics of Groundwater Flow and Tidal Flat formed by River Structure in the Estuary

Abstract

The variations of river flow by river structure created ecological tidal flat in Ota River. The formation mechanism of ecological tidal flat was analyzed by the distribution of soil environment and variation of water level and quality of the groundwater. In Ota River, groundwater level was kept high in main channel because tide pool is formed by the revetment in flood plane. The groundwater flow was occurred by the gradient of ground water level between tide pool and main channel with tidal variability. The high porosity in the tidal flat is kept by the variation of groundwater level. It is considered that tidal flat which content low organic matter is formed by transportation of organic matter which occurred by groundwater flow.