The method of Space-Time Image Velocimetry(STIV) can be expected to save labors and promote unmanned discharge measurement. A trail camera with the solar panel was able to be installed without commercial power and it required near-infrared illumination at night-time and effective distance was within around 50-60m. For a far-infrared camera should be combined with an image sharpening device in order to sharpen the water ripples. The effective distance was within around 150m same as visible camera. It could prevent random noise by stabilizing the current with the Uninterruptible Power Supply(UPS). The difference between the observed discharge and image velocimetry discharge was about ± 10%. As a result, it was possible to use the image velocimetry discharge for the calculation of the water level and discharge rating curve.
