Most of the rivers in Japan, in terms of river length, are small to medium-sized rivers managed by prefectural governments. Due to financial and human resource constraints, prefectural governments are not able to conduct river channel maintenance and management, such as weeding of embankments, river channel inspection, and cross-sectional surveying, which should be conducted on a regular basis. Under the climatic changes, many small and medium-sized rivers have suffered from flood damage. The implementation of river channel maintenance is also important to reduce flood risks. On the other hand, in Japan, there has been a system of river protection activities in which local residents weed and clean the embankments since a long time ago. In addition, some communities have a system to report to the government when residents find abnormalities such as deformations or sediment accumulation on the banks during protection activities or on a daily basis. However, in some cases, the information is not fully utilized for river maintenance and management due to inadequate reporting forms and manuals, lack of expertise, and other factors. We believe that the information provided by residents, is important for assessing flow capacity, inspecting facilities, and monitoring the river channel. In this study, we examined what kind of technology is easy for residents and river administrators to handle, and investigated the optimum UAV photogrammetry operation by using the river information from local residents. As a result, we proposed an accurate and cost-effective observation method with the river information.
pp.206-207.