HySwap Area-Based Runoff Duration Hydrographs — Massachusetts (7-Day Statistic)

This resource provides a Jupyter Notebook workflow for computing and visualizing area-based runoff duration hydrographs for HUC08 watersheds in Massachusetts using the USGS hyswap (Hydrologic Surface Water Analysis Package) Python package. Daily mean streamflow records are retrieved from the USGS National Water Information System (NWIS) for all streamgages with drainage basins that intersect Massachusetts HUC08 watersheds. Streamflow is normalized by drainage area to produce runoff in millimeters per day and aggregated to the HUC08 scale using an area-weighted mean approach. A 7-day rolling average is applied prior to analysis. Variable percentile thresholds (5th, 10th, 25th, 50th, 75th, 90th, and 95th percentiles) are computed by day-of-year from the full historical record (1990-2024), and Water Year 2024 runoff is overlaid on the resulting percentile envelope for each HUC08. The notebook is designed to run directly on the CUAHSI JupyterHub Python environment with minimal setup.