Field Measurements of Floating-Litter Transport in a Large River under Flooding Conditions and its relation to DO Environments in an Inner Bay

Abstract

To examine temporal variations of floating-litter transport and evaluate annual flux into Tokyo Bay, we did field measurements of floating-litter transport in a large river (Edogawa River) under flooding conditions. We also did a laboratory experiment to investigate the effect of the litter on the dissolved oxygen (DO) consumption of the water column. The results indicate that the peak of the floating-litter transport in flooding events are significantly different with that of the discharge, and show an appreciable dependence of the temporal variations of floating-litter transport on the flooding conditions. The annual volume of floating litters flowing into Tokyo Bay under large-scale flooding condition is an order of 10⁵ [m³], and thus the DO consumption of floating litter in this condition may be almost the same as those of bottom sediments and river water.