ダムにおける堆砂対策の現状と課題 : 矢作ダムを事例として(平成20年度日本水産工学会秋季シンポジュウム「内湾における環境修復の方向性と新手法」(1/2))

概要

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With respect to the sediment problems in the Yahagi dam, we examine both short-term and long-term measures. First, as an urgent, short-term measure, we are excavating the sediment accumulated on the upper parts of the reservoir, so that the dam can retrieve the flood control function up to the beginning level. The excavated sand is used effectively for park maintenance in Toyota city and for the tide-land development project in corporation with Aichi prefecture. Second, as a long-term resolution, we consider developing a sand-exhausting system that excretes only the amount of sand that goes beyond dam capacity by combining Hydraulic Sedimentation Removal System and Sand-Exhausting Bypass. However, it is supposed, according to a result of a trial calculation, that most of the sand exhausted from the Yahagi dam will flow downward and accumulate on the lower dams for power generation. We thus are required to consider such sediment problems from the viewpoints of comprehensive sediment management. Specifically, what should be taken into consideration is to maintain the functions of the Yahagi dam as well as of the lower power dams, to run the sand exhausted from the Yahagi dam along through the lower rivers without making further sand accumulation, and to suppress the total cost.
2009-11-15