Inhibition of Anaerobic Water Layer Formation Using a Multifunctional Aerator Installed in Hiyoshi Dam (Time-Series Analysis of Deep-Water Dissolved Oxygen Concentrations and Aerator Performance after Aerator Operation)

摘要

Multifunctional aerators co-developed by the Japan Water Agency in 2009 were designed to simultaneously fulfill two main functions related to water quality: oxygenation of deep water layers to relieve anaerobic conditions, and promotion of circulation of shallow water layers to prevent algal blooms. In contrast, conventional aerators work effectively for either deep layers or shallow layers, but not both. Since the multi-functional aerators were developed, 10 have been installed in four dams in the Yodo-gawa River catchment, and in other dams in Japan and Vietnam. In this study, a field experiment was carried out at Hiyoshi Dam (Lake Amawaka, Kyoto Prefecture, Japan) in spring 2016 to examine the effectiveness of the aerator in preventing the establishment of anaerobic conditions in deep water layers. In the experiment, the vertical distribution of dissolved oxygen (DO) concentrations was measured around one of the aerators installed near the dam wall for a three-day period after the aerator was in operation. Time-series analysis of DO concentrations revealed that the oxygen transfer coefficient of the aerator was 10 to 20%, which corroborated the values predicted in our previous studies.