STUDY RELATED TO THE CHARACTERISTICS OF OXYGEN DEFICIENCY IN UPSTEAM LAYER OF RUBBER GATE-TYPE SHUTTER WEIR FLOW SECTIONS

Abstract

 Oxygen-deficient water masses occurring in the lower upstream layers of rubber weirs and flows of water with poor oxygen due to the collapsing of rubber weirs considerably affect the water quality in downstream dam reservoirs. Therefore, in this study, we organize and analyze the results of existing water quality survey, elucidate the characteristics under which oxygen-deficient water masses occur, and construct a quantitative model of dissolved oxygen consumption because of sediment. We confirmed the validity of the numerical analysis model through a comparison with actual results. The results of this investigation revealed that oxygen-deficient water masses were distributed in areas with an approximate depth of 4 m from the upstream of the rubber weir to the intermediate region. In addition, The daily minimum total flow volume applied to the collapsing, as calculated using the sediment oxygen consumption rate estimated values, should be at least 0.3~0.8 times that of the reservoir capacity.