FIELD OBSERVATION OF SCUM USING FIXED-POINT CAMERAS IN AN URBAN TIDAL RIVER, OSAKA

Abstract

 Floating scum (sludge) combined with sewer overflow has been observed after rainfall in urban tidal rivers. An early solution for this is required from the viewpoint of the urban landscape, stench, and public health issues. We constructed a scum-observation system comprising flow and water quality meters and fixed-point cameras to investigate the flow and water quality characteristics and the behavior of scum in the Hirano River.

 Our results demonstrated that not only the diurnal and half-diurnal tides but also the tidal components of one-fifth to one-sixth days of the natural vibrations of the Osaka Bay and the Kii Channel had a negligible influence on river flow. The scum appeared throughout the year and was often observed for a few days after rainfall. It was observed that while the scum was transported based on tidal movements, the effects of human factors such as ship navigations also strongly influenced the behavior of the scum in the river.