天竜川河口域の出水と波浪による地形変動の観測 Observation of morphological changes due to floods and waves at the river mouth of Tenryu

Morphological changes at the river mouth of Tenryu by floods and waves are observed continuously with a X-band radar for years 2010 and 2011. X-band radar grasps the shapes of the river channel and sand bar,and the submarine extent of river terrace formed at the seawards of the river mouth. When the river water level increases,flood flow erodes the sand bar,and sediment is fed to expand the river terrace. After the flood,recover of the sand bar starts and its tip migrates to close the river by the action of oblique incident waves. At the same time,river terrace starts to shrink also by the action of waves. The amounts of these changes were estimated from the result of X-band radar observation and were reasonably well correlated with the flood intensities and wave energy fluxes.