CLARIFICATION OF SILTATION MECHANISM OF INTERTIDAL FLAT DUE TO RIVER FLOOD

Abstract

 Clarification of sediment transport in intertidal flats is very important for conservation of intertidal flat and future prediction. Furthermore, since the river basins is closely related to the quality and weight of sand supply, it is important to clarify the regional sediment transport. In this study, we studied Nakatsu Intertidal Flat. Nakatsu Intertidal Flat is sandy and muddy tidal flat. However, in recent years, there is concern about it has erosion and siltation. Moreover, salient siltation of Nakatsu Intertidal Flat was observed from spring to autumn 2017 from field observations by the previous authors. In this study, we targeted North Kyushu Heavy Rain Disaster in July 2017 and verified siltation mechanism of Nakatsu Intertidal Flat from numerical simulations of sediment discharge from the river and regional sediment transport of coastal zone and river. As a result, we obtained spatial distribution of suspended mud and settling velocity of suspended mud corresponding to tidal and river discharge. Therefore, we were able to qualitative reproduction of mud transport in intertidal flats.