| A gravel-bar restoration project was started in 2001 in the Nagata District of theTama River. As a part of the project, gravel augmentation was conducted as a trialin 2001 and the work is continuing. The objective was to increase the riverbedheight and to maintain gravel-bar area, but there were some concerns about thedownstream region, such as local deposition of sediment which would reduce thedischarge capacity. This paper reports on the following field study. First, across-sectional survey was carried out to confirm whether gravel augmentationwas effective for gravel-bar restoration. Secondly, gravel movement was measuredwith a low-frequency communicator to identify where imported gravelaccumulates after a flood. From these observations, it was found that most of theimported gravel flowed downstream during a flood and tended to stop around thelower area of the Nagata District. However, local deposition of sediment was notobserved downstream of the Nagata District. |
