An integrated space-air-ground approach for monitoring pollution flux in river sections:a case study of the Jiyun River section
In order to study a long-time series,low-cost,high-precision method for basin-scale non-point source(NPS)pollution flux estimation based on space-air-ground integration,this study focused on the Jiyun River as an experimental section.And a non-contact estimation approach of NPS pollution flux was employed by integrating multiple monitoring methods,including unmanned Aerial Vehicle(UAV),unmanned vessels equipped with Acoustic Doppler Current Profilers(ADCP)devices and remote sensing.Sentinel-2 L2A data from 2022 was utilized and the river's surface width was extracted through the Normalized Difference Water Index(NDWI)and Otsu's threshoding method.Discharge calculation for 2022 was performed based on the Manning formula,integrating both the digital model and the extracted river width.Total nitrogen pollution flux was estimated using water quality monitoring data.Results indicated that the river width extracted from Sentinel-2 imagery exhibited an error margin of 1-2 pixels,with deviations ranging from-13.5 m to-5.52 m when compared to high-resolution data.The calculated trends in river flow and total nitrogen pollution flux was consistent with results form statistical methods.This study highlights the efficacy of space-air-ground integrated monitoring technology in accurately estimating pollutant flux,serving as a valuable supplement to traditional ground monitoring,while effectively reducing costs and supporting large-scale pollution assessments.
digital river channel modelriver dischargetotal nitrogen pollution fluxspace-air-ground integration
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