報告書番号

V13007

タイトル（和文）

土砂動態を把握するための水質観測システムの構築と試験運用

タイトル（英文）

Construction and trial operation of water quality observation system for sediment transportation

概要 （図表や脚注は「報告書全文」に掲載しております）

通砂運用は、ダム貯水池や水力施設の管理運用上問題となる堆砂を除去する効果的な技術の一つである。しかしながら、通砂は、河床や河川から河口までのハビタットといった環境に影響を与える可能性がある。土砂動態の把握には、リアルタイムかつ長期に渡る観測が必要となる。そのため、耳川においてダム貯水池から河口の間の3地点に観測システムを設置し、試験運用を開始した。本観測システムは、荒天時もデータの取得や河川水のサンプリングが可能であった。また、採取した河川水中の濁質の粒度組成は、時空間的なばらつきを示し、今後、流下方向の濁質組成の詳細を調べることで、土砂動態を把握できる可能性が示唆された。

概要 （英文）

Sediment slucing is one of the effective techniques to remove sediment for better management of the dam reservoirs and hydraulic power plants. However the sediment slucing would cause an environmental impact on river bed and habitat over estuary from dam reservoir. Real time and long term monitoring need to evaluate sediment dynamics. Therefore a monitoring system was constructed at three locations from dam reservoir to estuary in Mimikawa River and trial operation of the system was conducted.
The monitoring system performed to transmit water quality data, and water was simultaneously sampled from the river during stormy weather. Grain size composition in sampled water changed in spatially and temporally, especially a fine particle decrease with a coarse particle increase in downstream. This result indicates that the sediment dynamics would evaluate by a detailed investigation of the suspended sediment condition in the flow down direction. On the other hands, communication devices stopped lots of times between May and June due to loss of power. In order to decrease electricity consumption, the power source of communication device controlled alternately turn on and off every fifteen minutes. Long term monitoring system was constructed successfully.

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