2022 Volume 78 Issue 2 Pages I_643-I_648
Numerical simulations of regional sediment transports from river basins to coastal zones are important in order to propose comprehensive countermeasures for river and coastal sediment problems. In such simulations, one of important factors is the treatment of boundary conditions of river discharges and sediment discharges. In this study, numerical simulations of regional sediment transports from river to coastal zone by using a regional sediment transport of mud/sands and morphodynamic model by considering tidal and coastal currents : WDM-POM and a river sediment model by using a simple model and observation data : gRSM. In these simulations, several conditions of river discharges were applied and discussions were made especially on differences of coastal sediment movements by comparing between numerical results and observation results of remarkable siltation of Yamakuni River and Nakatsu Intertidal Flat due to North Kyushu Heavy Rain Disaster in 2017. First of all, numerical results by using boundary conditions of river discharges with hydrographs revealed qualitative agreements with observation results in terms of siltation. Furthermore, in conclusions, boundary conditions by using hydrographs were very important and time relationships between the hydrograph and tidal elevations affected severely on sediment movements of the intertidal flat. By using optimal boundary conditions, accurate simulations will give answers of mechanisms and countermeasures of erosion/deposition and siltation.
