富山県出し平ダムの排砂ゲートから排出された黒色濁水の特徴

Dashidaira Dam and Unazuki Dam at Kurobe River, Toyama, Japan are regularly flushed sediments since 1991. The flushing of sediments has been impacted on ecosystem of under stream and Toyama Bay. Parameter of river water, such as pH, Eh, EC and DO at four places, were measured. Clay mineralogical components of dam sediments conducted in the two reservoirs have made it possible to evaluate the characteristics of sedimentation. Biological data are also essential because they allow comparisons to be made with conditions upper and lower of the dam sediments. At 15:30 on July 14 th, 2002, dark sludge with low oxygen was flushed from Dashidaira Dam, which was collected from Ononuma Park. The dark sludge contains expandable clay minerals with strictly anaerobic bacteria, indicating pH 6.8, Eh -210 mV, EC 143μS/cm and DO 0.9 mg/l. Physical, mineralogical and biological properties of flushed dam sediments(dark sludge) from Dashidaira Dam differ from the upper clean stream cause strong negative in downstream of Kurobe River. It had better leave river alone.