SURVEYS OF RIVERBANK GARBAGE IN THE YAMATO RIVER

Abstract

 In order to understand the behavior of garbage in rivers, which is the origin of marine debris, it is important to understand the transport process of garbage production - release - deposition - resuspension. However, most research has focused on the amount of discharge or drift, and management authorities inspect riverbanks and have organized data about the amount of collected garbage. This study conducted field surveys of garbage in the Yamato River, where water quality has been improving in recent years but the deposition and littering of garbage remain a stubborn issue, in order to understand the state of garbage scattered on the riverbank. Patrol records indicate a large amount of garbage drifted 5.0 km from the river mouth and its downstream, indicating that the deposition of garbage is similar to the sediment deposition characteristics. In the field survey, 1m square quadrats were set up and 31 samples of man-made litter were collected at 7 locations. The weight, number of pieces, and coverage of garbage were measured and their relationship was analyzed. The weight per 1% coverage was estimated to be about 30g/m², and the weight of garbage larger than 5cm on the short side was estimated to be about 12 g per piece.