Measurements and prediction of typhoon-induced short-term general scours in intermittent rivers

Most rivers in Taiwan are intermittent rivers. A short-term general scour usually occurs in the river during the rising limb of a flood due to the transitory sediment imbalance and the steep slope gradient. In this study, a severe maximum general scour depth of 4.5 m was measured near the Highway Bridge hydrological station in a gravel-bed reach of the lower Dajia River, which was caused by a flood induced by Typhoon Sinlaku in 2008. This type of short-term general scour is usually very significant and cannot be neglected as it has caused many casualties in Taiwan such as bridge and embankment failures, for example, the Houfeng Bridge failure in the lower Dajia River (Hong et al. in J Hydraul Eng ASCE 138(2):186–199, <CitationRef CitationID="CR11">2012</CitationRef>) and the Shuangyuan Bridge failure in the lower Gaoping River. Based on the collected field data, a general scour formula was developed and gave reasonable predictions. In conjunction with the real-time ultrasonic water level measurements, the formula can be used as a potential tool for the emergency evacuation or bridge closure purposes. Copyright Springer Science+Business Media Dordrecht 2013