Exploring the Influence of Urban Watershed Characteristics and Antecedent Climate on In-Stream Pollutant Dynamics

Understanding pollutant fate and transport in urban watersheds is a challenging endeavor, as heterogeneity of land use, precipitation patterns, and pollutant loadings add complexity to the system. As a result, many currently utilized water quality models exhibit poor performance. One main challenge in urban system modeling is the lack of quality data sets for model development, calibration, and testing, resulting in the need for high quality data collection. Although recent studies have begun to investigate pollutant transport in urban watersheds to aid these models, these studies have focused primarily on the end-of-pipe as the point of interest (i.e. prior to stormwater entering an open stream channel). However, it is likely that in-stream processes will influence pollutants leaving urban watersheds when the system is viewed at a larger scale. The results of the high-resolution sample collection performed in this study improve our understanding of water quality trends at the watershed scale (including the influence of in-stream processes), and ultimately can be used to improve urban watershed water quality models. Studies have shown correlations between runoff water quality variability and land use classification, antecedent climate, and rainfall factors. Further investigation in urban streams could support these parallel relationships. The goals of the study include: (1) identify trends in water quality due to watershed characteristics using two inter-storm analysis methods, and (2) report the effects of explanatory factors on these trends in Knoxville, TN, streams. Ultimately, this study intends to contribute to water quality prediction during storm events by analyzing how watershed characteristics, rainfall patterns, flow regimes, and antecedent climate factors affect water quality.