Middle Koba dam (the June, 2007 completion) Nakakoba Dam
The last update date:
In 1962, river overflowed by floods such as 1976 and, in the lower valley of Nakagawa of Kashima river water system, was hit by unprecedented large flood.
Therefore, we built dam in total in upper basin and, in the prefecture, decided to plan reduction of flood damage with river repair as river improvement countermeasures of Kashima river water system.
In addition, development of new water supply water source became urgent business to plan water source switch because we depended on unstable groundwater for water source of water supply water in Kashima-shi, and problems such as decrease of subsidence and quantity of water, aggravation of the quality of the water occurred.
Thus, we planned construction of middle Koba dam as multipurpose dam in upper Nakagawa region of the right supporting river of Kashima river to plan flood control, stabilization of existing profit water intake, maintenance of river environment and securing of water source of water supply water of Kashima-shi in the prefecture.
We started the dam body construction in October, 2001 and started hisagetai concrete casting in September, 2003. Casting of all concrete of the body was completed in 2006 and completed examination flooding on May 19, 2009.
- The business main constituent: Saga
- Water system name: Second class water system Kashima River
- River name: Nakagawa
- Position: Yamaura, Kashima-shi, Saga
- Model: Gravity-type concrete dam
- Dam summary:
- The amount of bank: 69.5m
- Mayor of bank top: 265.0m
- Bank volume: 313,000m3
- Catchment area: 13.5km2
- Total storing water capacity: 6,800,000m3
- Valid storing water capacity: 6,300,000m3
- Term of works: From 1978 to 2006
- Total operating cost: 33,650,000,000 yen