Assess students' ability to apply the water‑balance equation at a watershed scale to quantify how urbanization (increased impervious area) alters runoff and streamflow. Tasks include identifying and using required components (precipitation, evapotranspiration, runoff/discharge, storage change, infiltration/groundwater exchange), setting up pre‑ and post‑development water‑balance calculations from provided data or simplified assumptions, estimating changes in peak flow, baseflow, and seasonal discharge, interpreting hydrograph modifications, and justifying assumptions and uncertainty in results. Scope: grade 9–12, medium difficulty, spreadsheet or hand calculations, watershed-scale scenarios with given precipitation and ET inputs.