1994 Volume 38 Pages 747-752
Between June and August, 1993 field observations and measurements of debris flows have been carried out at two locations on Mount Unzendake. One of the instrumented study sites was a downstream reach of the Mizunashi River, which is11.6m wide and have an average slope of about 2.9°. The other was a downstream reach of the Nakao River, which is 7.2m wide and have an average slope of about 1.4°. Radio current-meter and ultrasonic water level gauge were used to obtain surface velocity, depth and discharge for the several flows.
The value of nondimensional surface velocity us/u* was found 5. Peak discharge was found Q=195m3/s at the Mizunashi River and Q=40m3/s at the Nakao River. Spectra of velocity and water-level variance shows maximum at f≈10-2Hz.