How did the Zuihoji River shape the landscape we see today? The Zuihoji River is a vital waterway. It flows through the heart of Fukuoka Prefecture. This river creates a tapestry of natural beauty and historical significance.
The Zuihoji River is a Class B river. It stretches 13.2 kilometers. Its basin area covers 52.6 square kilometers. The river originates from Mt. Iwara in Ito City. The water source sits at an elevation of 420 meters. The river flows into Hakata Bay in Fukuoka City’s Nishi Ward. The Zuihoji River helps form the Itoshima Plain. It merges with the Raizan River system. Locally, it is also called the Iketagawa River.
The river’s journey begins in the foothills of Mt. Iwara. Two small waterfalls cascade. The upper one is the Anno Falls with a 13-meter drop. The source area is part of the Sefuri Raizan Prefectural Natural Park. As the river descends, it becomes the main entrance to Mt. Iwara. City-operated facilities welcome hikers. Below the Kidoku Bridge the Zuihoji River becomes a designated river. The Fukuoka Prefectural Route 563 runs parallel. It follows the Zuihoji Iketagawa Line to the Tatara River. Passing the Iwara Bridge the river feeds the Zuihoji Dam’s reservoir. It merges with the Nishi-no-Tanigawa River.
The Zuihoji Dam is 64 meters high. Below the dam the river flows at an elevation of 150 meters. From the Zuihoji Bridge, you can see terraced rice fields. The river’s current slows. The Raizan River flows parallel to the west. Residential areas of Sogane are located on higher ground between them. The Kawaara River flows to the east. Paddy fields dominate the landscape.
The middle reaches of the Zuihoji River were once likened to the Ito district during the Yayoi period. Many historical sites dot the area. These include the Miyake Minami Komichi ruins and Tsukiyama and Hozumi ancient tombs. The largest tributary is the Kawaara River. It merges with the Tatara River. The Zuihoji River passes the Nishikyushu Expressway. It then flows through Itoshima City. It flows between the Tatara River and the Meinohama area of Fukuoka City. Near its mouth, the river creates a wide paddy field.
Tidal flats mark the river’s end. Here it joins the Harada River and the Mikasaki River. The Zuihoji River flows into Hakata Bay. The Imatsu Bridge crosses the river near the bay.
The Itoshima Plain was formed by sediment. The Zuihoji River and Raizan River carried it. This connected the island peaks of Mt. Kaya and Mt. Ishigane to the mainland. The middle and lower reaches have little elevation change. This makes the area prone to flooding. The Zuihoji Dam was built to mitigate flood damage. It also meets the growing water demands of Fukuoka City. Construction began in 1971. It was completed in 1977.
Heavy rains and Typhoon No. 6 caused flooding in 1985. Thirty-two homes were damaged. This led to river improvements. Work began in 1989 near the Harada River confluence. Embankments were built. The riverbed was dredged. Revetments were installed. Typhoon No. 17 caused further damage in 1991. The Zuihoji River breached its banks in two places. Four hundred seven homes were flooded. Rice paddies were submerged. River improvements became urgent.
Today the Zuihoji River is managed. It balances flood control with environmental concerns. The goal is to handle floods. This should occur about once every ten years. The work focuses on the lower reaches. It extends from the Showa Bridge to the Wakamiya Bridge.
The Zuihoji River has a history of water scarcity. The dam’s effective water storage is 2.27 million cubic meters. Fukuoka City and Kihara have water rights. But this is not always enough. A severe drought hit in 1978. Water restrictions lasted for 287 days. Similar droughts occurred in 1994. The Zuihoji River faces challenges. Silt accumulation and changes in farming practices affect it. The dam operations need to be flexible.
The Zuihoji River shows nature’s power. It also shows human efforts. This ensures safety for the community. It also provides vital resources. It remains a testament to the relationship between the people and the land.