Four years have passed since the heavy rain disaster in July 2018.
A grand project to relocate the confluence point of the Odagawa River and the Takahashi River approximately 4.6 kilometers downstream to the Funao area from the current Mabi area is being rapidly advanced with the aim of completion by the end of the 2023 fiscal year.
This project is expected to reduce the impact of backwater phenomena from the Takahashi River during floods, lower the water level of the Odagawa River, and increase safety.
A site briefing was held on November 12, 2022, and we will convey the details of that event.
What is the Odagawa Confluence Relocation Project?
The site briefing was held as a citizen lecture, and the explanation was provided by staff from the Takahashi River and Odagawa Emergency Flood Control Measures River Office of the Chugoku Regional Development Bureau of the Ministry of Land, Infrastructure, Transport and Tourism, which is the project entity.
Initially, the project was aimed for completion in the 2028 fiscal year.
However, due to the heavy rain disaster in July 2018, the urgency was reassessed, and the construction period has been shortened to be completed by the 2023 fiscal year under the "Special Emergency Measures for Severe River Disasters (Gekitoku Project)".
Current Confluence Point of the Odagawa and Takahashi Rivers
First, let’s take a look at the upper right of the photo above.
▼The water surface on the right is the Takahashi River flowing from the back to the front, and the Odagawa River is merging from the left into the Takahashi River.
▼This is the Odagawa River just before the confluence.
The white structure extending is the cutoff embankment, which will be further extended to block the Takahashi River and the Odagawa River.
Excavation of Minamiyama and New Odagawa River Course
Next, let’s look at "Minamiyama" located in the center of the above photo.
▼Minamiyama, where a mountain castle is believed to have been built during the Sengoku period, had excavation work begin after the archaeological survey was completed.
After excavation, a new course for the Odagawa River will be established, leading to the new confluence point.
Work is still ongoing, and the excavated soil is being utilized as embankment material.
▼Large machinery is transporting soil and sand.
The central embankment is a temporary placement of embankment material.
In the future, all of it will be removed, and the site will become the course of the Odagawa River.
The white wall on the left is planned to be the left bank embankment of the Odagawa River.
Yanaihara Reservoir and New Confluence Point
The new Odagawa River will flow through the Yanaihara Reservoir to the new confluence point.
The above photo shows the reservoir viewed from the downstream side.
The equipment installed for water treatment during construction will be removed after the project is completed.
▼A new bridge, the Shin Yanaihara Bridge, was completed in August 2022 just before the new confluence point.
A new course will be created by removing the current embankment, which is currently being used as a substitute for the city road on top of the embankment.
The title is by Kurashiki City Mayor Kaori Ito.
The new confluence point has not yet revealed its form.
Just downstream of the Kurashiki Ohashi Bridge (where the Takahashi River flows from left to right below it) will be the new confluence point.
Conclusion
The above photo was taken from the Takahashi River side of the cutoff embankment that blocks the Oda River and the Takahashi River in 2020.
The 10-year plan for the construction work has been shortened to 5 years, and early completion is expected. It seems that this has visualized for the local community what will be done and by when. The project is being advanced towards completion within the construction period.
By relocating the confluence point, not only will the "backwater phenomenon" caused by the Takahashi River blocking the flow of the Oda River be alleviated, but the water level at the Sakazu point of the Takahashi River will also decrease, improving safety.
As of November 2022, the construction is progressing smoothly, and completion as planned is expected.
I would like to express my gratitude to everyone involved in the construction.
With just over a year remaining until completion in March 2024, let’s look forward to its completion.
Kurashiki Citizen Lecture "Towards Reconstruction - Embankment Improvement in Mabi and Relocation of the Oda River Confluence Point" Data
| Name | Kurashiki Citizen Lecture "Towards Reconstruction - Embankment Improvement in Mabi and Relocation of the Oda River Confluence Point" |
|---|---|
| Date | November 12, 2022 |
| Location | 1141-1 Ayata, Mabi-cho, Kurashiki City (1st floor of the former Mabi Health and Welfare Hall) |
| Participation Fee (Tax Included) | Free |
| Homepage | Takahashi River and Oda River Emergency Flood Control Office |
