Author(s): Ichiro Fujita; Yoshifumi Kosaka; Masato Honda; Atsuhiro Yorozuya; Yoshiki Motonaga
Linked Author(s): Ichiro FUJITA
Keywords: Flow measurement; Image analysis; Snow-melt flood; STIV; Far-infrared-ray camer
Abstract: Data acquisition of river flow information especially at a peak flow condition is indispensable for a proper management of a river basin. However, due to the difficulty of conducting a float method appropriately in an extremely fast flow condition, non-contact methods such as imaging techniques or radio wave velocity meters have become available as alternative methods. Among them, imaging techniques used to have a weak point difficult to apply during the night, but in the present study this problem was found to be solved by using a far-infrared-ray camera. The study areas was the Uono River in Honshu Island in Japan. The river is known to be flooded in the early spring season by a snow melt flow. At the site, we measured the flood by various methods such as a radio wave velocity meter, an ADCP and surface tracers in addition to the imaging technique, the space time image velocimetry (STIV). The measurements were conducted from morning till nighttime every hour mainly at the downstream of a bridge in order to compare the data measured by a boat-mounted ADCP. It was made clear that the far-infrared-ray camera can capture the water surface features more clearly than normal cameras even with its low resolution of 320 by 240 pixels. Furthermore, it was demonstrated that measurements during the night can be conducted without any difficulty by using the far-infrared-ray camera with STIV and discharges estimated from STIV data agree fairly well with ADCP data.