Author(s): Ken; Apos; Ichi Takada; Tetsuya Yabiki; Makoto Nakatsugawa; Yasuhiro Murakami
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Keywords: Sedimentation; Water quality; Musty odor; Geosmin; Actinomycetes; Hydraulic analysis for the reservoir
Abstract: The water environment of dam reservoirs is greatly influenced by sediment inflow from upstream, weather, and hydrological conditions. The Izarigawa Dam was completed in 1980, and sedimentation has been progressing yearly. The volume of accumulated sediment was 840,000 m3 as of 2002. A sediment shelf formed in the dam reservoir has been advancing and it became conspicuous in 1993, when musty odor occurred from the action of actinomycetes. Nearby residents complained about this musty odor. In view of the above, we compiled existing survey data on transitions of sediment accumulation and hydrological and water quantity conditions of the reservoir toward constructing a hydraulic model. Under the assumption that the inflow conditions are constant, this model was used to calculate the hydraulic conditions of water flow before sedimentation (i. e., immediately after dam completion) and after sedimentation. The results show changes in water flow and temperature, which enabled us to clarify the mechanism of musty odor generation. Toward developing countermeasures against musty odor, we will quantify its causal factors.
Year: 2004