Mechanism of Fine Particles Movement Caused by Groundwater Flow in Tidal Flat

In the previous studies, it was pointed out that mahogany clams live at the deeplayer (80cm from ground surface) of the tidal flat located at the midstream of Hiroshima's Ota River. It is believed that a current of water transports organic matter for food into the deep layer of the tidal flat. In this paper, a series of field observations and laboratory experiments was undertaken to look into the mechanism of organic matter movement under the effects of groundwater flow. In the field observations, variations in fines content and ignition loss provided evidence that organic matter was transported by groundwater flow to the deep layer of the tidal flat. From the laboratory experiment results, the permeability and the critical condition of organic matter movement were demonstrated with respect to the void ratioand velocity of the groundwater flow.