What is an estuary barrage?
“Estuary barrage” is a barrage across a river at its estuary. According to flow-rate of the river and the rise and fall of the tide, the gate of the barrage is opened or closed to protect people living in the river valley from floods and to stop seawater from running up the river to prevent salt damage around the region.
Currently, The Kyu-Yoshinogawa Estuary Barrages Management Office mainly makes good operation and maintenance the Imagiregawa Estuary Barrage and The Kyu-Yoshinogawa Estuary Barrage. These two estuaries have three major roles.
(1) To protect people living in the river valley from floods
When a heavy rain occurs during a rainy or typhoon season, the barrages immediately release accumulated water to downstream.
(2) To stop seawater from running up the river to maintaine the function of river
The barrages control water flow, stop seawater running up and maintaine the functions of river.
(3) To provide water to households, factories and agricultural fields
Upstream water at the estuary barrages is used for drinking water as well as industrial and agricultural purposes.
- Domestic water: Water supply to Naruto City, Kitajima Town and Matsushige Town comes from the Kyu-Yoshinogawa River. The population supplied with the water is estimated at 60,000 in Naruto City, 20,000 in Kitajima Town and 20,000 in Matsushige Town, respectively, with the total of 100,000.
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Industrial water: Industrial water to the area on the north bank of the Yoshinogawa River comes from the Kyu-Yoshinogawa River. The water is provided to 22 factories in Tokushima City, Naruto City and Itano County.
Other than these, Naruto Factory of Nichia Corporation also takes water from this river. - Agricultural water: The area to which water taken from the Kyu-Yoshinogawa River and the Imagiregawa River is provided is about 3,700 ha. In this region, high-quality agricultural products such as rice, sweet potatoes, lotus roots, carrots and pears are produced.
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