茨戸川の水質改善に向けた導水効果の検証

抄録

To improve the water quality of the Barato River, there are plans to introduce water into that river from the Ishikari River. The plans were implemented on a trial basis at the Barato River in 2005, and BOD was found to decrease, confirming water quality improvement. Downstreamward flow of the introduced water predominated over backflow, and water quality improvement at the upper reaches of the Barato River was much greater than at the lower reaches of that river. Onsite observations, a water-quality prediction model and the water budget measurements indicated that dilution and runoff were the most significant factors for water quality improvement. It was also indicated that the introduction of water brought the greatest reduction in BOD when it was done at the uppermost reach of the Barato River and that the introduced water brought about the direct effects of dilution and runoff and the indirect effects of reduction in backflow load and in internal production.