Test students' ability to analyze watershed-scale nitrogen loading (nitrate, ammonium, organic N) responses to land-use change and climate variability using coupled hydrological and biogeochemical models. Tasks include designing scenario simulations, selecting and justifying model structure and parameterization, performing calibration/validation and sensitivity/uncertainty analyses, interpreting model outputs (time series, load-duration curves, export coefficients), attributing changes to processes (runoff, leaching, denitrification, groundwater–surface interactions), and evaluating management implications and model limitations. Scope: advanced undergraduate understanding of watershed processes, model evaluation metrics, and scenario-based policy recommendations.