[Environment Monitoring] Comparison of SWAT Streamflow and Water Quality in an Agricultural Watershed
SI Imaging Services
This study investigated streamflow and water quality using the Soil and Water Assessment Tool (SWAT) and by applying two land use datasets from KOrea Multi-Purpose SATellite (KOMPSAT)-2 and Landsat TM (Thematic Mapper) images. For a 262.3 km² agricultural watershed located in the northwest part of South Korea, the Landsat TM and KOMPSAT-2 could produce 8 and 25 land use classes from spatial resolutions of 30 m and 2 m, respectively. For each land use condition, the SWAT model was calibrated and validated using 8 years (2000-2007) of daily streamflow and monthly sediment, Total Nitrogen (T-N), and Total Phosphorous (T-P) data. The average Nash-Sutcliffe model Efficiencies (NSEs) of streamflow for KOMPSAT-2 and Landsat were 0.80 and 0.71, respectively. The average NSEs of sediment, T-N, and T-P were 0.52, 0.97, and 0.67 for KOMPSAT-2 and 0.30, 0.77, and 0.35 for Landsat, respectively. From the difference in the areal statistics and distribution between the two land uses, the key parameter for streamflow calibration was SCS-CN (Soil Conservation Service-CN). The watershed average SCS-CN value from KOMPSAT-2 was 1.05-fold greater than that from Landsat TM. The larger SCS-CN value increased the surface runoff and subsequently increased the sediment, T-N and T-P transport in the stream.
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