Impact of Spatial Discretization of Hydrologic Models on Spatial Distribution of Nonpoint Source Pollution Hotspots
AbstractThe soil and water assessment tool (SWAT) was used to investigate the effects of hydrologic response unit (HRU) thresholds (0 20% on predictions of multiple variables by calibrated and uncalibrated models in a 10.4 km2 urban watershed in the U.S. Mid Atlantic region. Surface runoff, discharge, sediment yield, and nutrient yield were simulated in stream and on land, and used to spatially identify hotspots for each constituent. SWAT2012 was able to produce accurate discharge and nitrogen estimates that were not sensitive to HRU thresholds. HRU thresholds significantly affected sediment and phosphorus predictions in calibrated and uncalibrated models. Constituent hotspots identified by an uncalibrated model with a 0% HRU threshold were found to be acceptable for the urban watershed under study, except for sediment. Hotspots identified with calibrated models, with HRU thresholds of 5% or less, fit with the identification of on land sediment and nutrient hotspots. These findings suggest that researche.