Dr. Jon Duncan
Assistant Professor of Hydrology
Penn State University
Predicting water quality is a major scientific challenge and important societal goal. Analyzing the interactions among water, climate, ecosystems, landscape structure, and land use decisions are necessary for improved understanding of water quality and for effective watershed management. Here I focus on quantifying nitrogen sources, transformations, and transport mechanisms in both forested and urban watersheds. By synthesizing long-term datasets, high temporal frequency observations from sensors, and models, I gain important insights into watershed scale nitrogen dynamics. A key finding is that a surprisingly small area of the forested watershed is responsible for the majority of denitrification fluxes and the magnitude and timing of nitrate stream export at the watershed scale. In urban watersheds, these hotspots have been eroded away and the magnitude and timing of nitrate stream export is driven by hydrology and infrastructure in urban watersheds. Representing these key locations and critical times is necessary for water quality modeling and sets up a series of hypothesis about where to install best management practices and conduct stream restorations. Integrating spatially extensive (top-down) models with intensive site-specific (bottom-up) models holds great potential for understanding the role of heterogeneity in watershed hydrology and water quality in the context of land use change and climate variability.