Automated Watershed Dashboard for Classifying Infiltration- and Saturation-Excess Runoff

ABSTRACT: Identifying the runoff generation mechanism is helpful for decision-making and for selecting the most appropriate model to simulate runoff processes. Watershed managers require practical tools to understand how stormwater responds to changes in land use, urbanization, and climate variability. Many hydrologic models estimate runoff volume, peak flow, or flood frequency, but few tools clearly identify whether runoff is primarily driven by infiltration excess, saturation excess, or a combination of processes. This manuscript presents the development and conceptual application of an automated watershed management dashboard that integrates watershed delineation, rainfall-frequency data, soil infiltration capacity, antecedent moisture, and imperviousness in one interactive workflow. The dashboard delineates the watershed for a selected USGS streamgage, retrieves rainfall data for different storm durations and return periods, calculates rainfall intensity, estimates soil infiltration capacity, and evaluates antecedent moisture conditions. The classification framework compares rainfall intensity with soil infiltration capacity while also considering soil saturation and urban imperviousness. Based on these conditions, the dashboard classifies the likely runoff response as infiltration-excess runoff, saturation-excess runoff, or mixed runoff. Results are presented through an interactive map, tables, color-coded classifications, charts, and downloadable outputs. The dashboard is intended as a screening and decision-support tool that can support engineers, watershed managers, planners, and researchers in flood mitigation, green infrastructure planning, and ecological protection.