Monitoring macroplastic waste sources along the Umgeni River using unmanned aerial vehicles

Rivers are major contributors of plastic waste entering the oceans. The Umgeni River in Kwazulu-Natal, South Africa, runs through the densely populated city of Durban, with 3.5 million inhabitants and is estimated to emit 400 tons of plastic waste annually into the Indian Ocean. The banks of the Umgeni River are lined with plastic waste accumulations, derived from accidental, intentional, and natural accumulation. This study uses high-resolution aerial imagery and several hydrometeorological measuring sensors in the catchment to (1) locate, monitor, and quantify macroplastic waste hotspots along the Umgeni River; and (2) investigate the influence of hydrometeorological factors driving the spatio-temporal evolution of the hotspots. This novel attempt to map and monitor plastic waste sources along the Umgeni River could assist waste managers and communities with a framework for developing targeted waste removal practices and mitigation measures.