Applicability of statistical and modeling methods in assessing the basin-scale grey water footprint

Abstract

• The equations for calculating the total grey water footprint of the basin are modified. • The principles of parameter determination in statistical method are clarified. • Hydrological models are suitable for calculating the basin grey water footprints. • Applicability of different grey water footprint accounting methods was compared. The water footprint is a widely used indicator for water resource assessment, among which quantifying the grey water footprint (GWF) is essential in assessing the basin-scale water resources. Due to the lack of accurate data and parameters in calculating the GWF by statistical methods, a few studies have used the Soil and Water Assessment Tool (SWAT) model to assess the GWF. This study aims to explore the applicability of statistical and modeling methods for GWF accounting of a basin. The Fuzhou River basin (FRB) in Dalian, China, was used as a case study; the GWF in 2015 was assessed using the statistical and modeling methods, respectively. Results showed that the GWF calculated by the statistical method and the SWAT model were 4158.44 million m 3 and 4494.62 million m 3 , respectively. Both spatially exhibited a rise from the upstream to the downstream reaches, and a decrease from the mainstream river to both sides of the river. In comparison, the modeling method lowered the difficulties of data acquisition and generated a more refined spatial distribution of GWF; whereas the statistical method can provide a more comprehensive analysis of the GWF from each pollution source. Furthermore, the water pollution level of FRB was calculated as 11.88 and 12.84, respectively, by the statistical method and the SWAT model, suggesting that the current water resources in the FRB are seriously polluted, which may threaten the sustainable use of local water resources.