Estimation of the amount of waste plastics flowing into water using city garbage images

Abstract

A method for quantifying urban plastic waste based on objective by efficient observation has not yet been established worldwide.

In this study, we first developed a quantification model for waste plastic flowing from land to water in collaboration, and then analyzed city waste images obtained by citizen science through a smartphone applicarion (Pirika) to measure the amount of plastic waste flowing into water in the city.

For a quantification model at a certain location L, the total outflow amount can be estimated if the inflow amount to the waterside InB(L), the direct inflow amount InW(L), and the amount of cleaning are known. Therefore, we conducted actual measurements three times, and by photographing the waste scattered at the waterside and the waste that had fallen into the waterway with Pirika and then collecting the waste, we were able to determine InB(L), InW(L) and the amount of cleaning.

The third data after the cleanup was less than the difference data between the first and second times, and the effect of the trash pick-up event was confirmed as per the broken window theory.