Case Studies
If river improvement work is carried out that involves replacing bridges, it will require huge costs and time, and the same risk of flooding as now will remain until completion, so completing the work as soon as possible is also a major issue.
Considering the current state of the narrowed section, the representative methods for safely draining floodwaters are the “river improvement measures,” “flood retarding basin measures,” and “underground river measures,”. In addition to the above three plans, a detailed comparison was also made and the “measures plan using the underground river ” was adopted for the following reasons:
- The “measures plan using the underground river” is the most
- The “measures plan using the underground river” is expected to produce the earliest possible results.
- The “measures plan using the underground river” requires the least amount of compensation for houses and land acquisition. etc.
By adopting the underground river plan, the same effect as river improvement will be achieved, making it possible to drain floodwaters from heavy rains. By developing the underground river plan, flood water levels will be lowered even in the heavy rains, preventing floodwaters from overflowing from the Yagyu River, and making it possible to drain floodwaters through the Yagyu River and the underground river.
