庄川新川開削区間の河床変動調査報告

抄録

This report presents an outline of new river course excavation work completed in 1912 at the mouth of the Sho River and the results of a study of the present state of the river course based on measured rivetbed fluctuation data and the results of sounding performed by acoustic exploration. In the low water channel of the excavated part of the Sho River, groynes (wooden mattresses) installed at that time have reduced lateral erosion so that the longitudinal riverbed fluctuation (riverbed decline) is dominant. But in recent years, a tendency for the riverbed to stop declining can be seen. This is considered to be valuable evidence that the river course has stabilized in response to the flow regime that has appeared during the approximately 90 years since the new river course was excavated. The report also reveals that our ancestors had superior river technology capabilities as shown by the fact that the groynes constructed using wooden mattresses are still functioning adequately. The report also presents the results of soundings performed by acoustic exploration before and after a flood in July 2002 to introduce the state of efforts to more accurately clarify riverbed fluctuations (stability of a river course).