The Effects of Flooding on Shirakawa Delta Morphology

Floods can significantly alter the morphology of a delta, from inputting increased volumes of sediments to modifying the reach of incoming waves, currents, and other gravity-driven forces occurring within the near shore. Kumamoto experienced flooding in July 2012. This flood event altered the equilibrium profile of the intertidal flat area of the Shirakawa River. This research looks at these modifications and attempts to explain their long-term implications on the overall delta morphology. Data collected over a 30-year period was analyzed and profiles were generated to better analyze and assess the trend in delta morphological changes. Numerical predictions on delta morphology in the presence of gravitydriven sediment transport were applied to investigate the morphological changes related to the flood event. The slope of equilibrium profile is lower and steeper offshore, helping to explain the models created before and after the flood occurred