Using detailed monitoring data to simulate spatial sediment loading in a watershed

The use of watershed models as cost-effective tools to quantify the impact of conservation practices on water quality is often constrained by lack of data for model parameterization. This study uses short-term (3 years) detailed monitoring data to guide spatially distributed model parameterization and modeling analysis for suspended sediment in the Upper Esopus Creek Watershed (UECW) that is part of the New York City water supply. The calibrated Soil and Water Assessment Tool (SWAT) model simulated suspended sediment loading from tributary sub-basins and at the watershed outlet that were comparable to field measurements. Model simulations estimated that stream channels contributed the majority (85%) of stream sediment in the study watershed followed by upland erosion (11%) and point sources (4%), consistent with previous estimates and field observations. Long-term (12 years) simulation of the calibrated model was used to apportion the average annual sediment yields from tributary sub-basins which ranged between 12 and 161 t km(-2) year(-1). Model simulations were also used to understand the inter-annual variability and seasonality in suspended sediment loading in the study watershed. We demonstrate the wider applicability of short-term detailed monitoring for model parameterization and calibration, and long-term simulation of water quality using the SWAT model.