How can SPARROW model uncertainty be used to better understand the factors affecting water quality?
|Back to Top| SPARROW models are designed to account for the spatial variability in stream water-quality monitoring data by relating them to spatially defined environmental factors. Uncertainty in the models is quantified by the differences between measured and modeled estimates of stream load, commonly referred to as residuals. The calibration process is designed to minimize those differences. Measures of uncertainty are used to assess the quality of the fit of the model and are used to estimate the margin of error in the prediction of loads, concentrations, yields, and source contributions. Spatial patterns of high or low residuals that may be observed in maps may potentially reveal important environmental factors that may not be accounted for in the model. For example, a SPARROW model could consistently overestimate nitrogen loads in a specific part of a model region. Those large residuals may reveal a spatial pattern that coincides with a watershed characteristic that may be associ
