Quantifying land-based pollutant loads in coastal area with sparse data: Methodology and application in China

► We develop a systematic approach for quantifying land-based pollutant loads. ► This approach integrates raster GIS with USLE, SDR, and empirical export coefficient method. ► The proposed approach has been applied in two coastal bays where there is sparse data. ► We measure the source apportionment of land-based pollutant loads. ► We identify the critical areas of land-based pollutant loads.