OBSERVATION OF RIVER CHANNEL DEFORMATION IN ESTUARINE BASIN WITH X-BAND MARINE RADAR

Abstract

An X-band marine radar has been installed at the river mouth of Tenryu, Sizuoka, Japan, to observe morphological behaviors of river sand bar and channel configuration in the estuarine. Original images captured by the radar are averaged every hour yielding averaged images, which are analyzed to identify land regions and water lines. Sand bars deformed remarkably during the flooding due to Typhoon 4 in July, 2007. Sand bar in the river channel shrank and its position migrated in the downstream direction. Annual variation of sand bar volume within the tidal range has been estimated. It showed a seasonal variation: it increases in the summer seasons and decreases in winter. Seasonal losses and gains of sand volumes in an area of 1000 square m within the tidal range were in order of 10⁴ m³.