The Bassett Creek Watershed Management Commission hired Barr to update and recalibrate its hydrologic and hydraulic (XP-SWMM) model. Barr refined the subwatershed divides using existing water-quality model subwatersheds, current topographic data, and storm sewer data—delineating and modeling more than 1,150 subwatersheds. The model was also updated to accommodate runoff flows generated from Atlas 14 design storm events. The revised XP-SWMM model was calibrated using NEXRAD precipitation data along with flow and elevation monitoring data for two storms. Once calibrated, the model results were verified against the monitoring data for a third storm.
Barr then used the calibrated model to analyze the Atlas 14 100-year, 24-hour design event to characterize flow conditions in the watershed and along the creek to predict the 100-year flood elevations. Approximate inundation mapping of the 100-year, 24-hour event was developed using XP-SWMM model results and current topographic data. Results of the model update and calibration process were documented in a technical report.
In 2018, FEMA awarded a grant to the Minnesota Department of Natural Resources for updating the special flood-hazard areas within Minneapolis and St. Paul, preferably by leveraging existing models wherever possible. The DNR recognized the value of the Phase 2 XP-SWMM model and worked with the commission to enter into a pass-through funding agreement to update the model to meet FEMA modeling standards. The primary focus of the update is to modify the model based on surveyed data for hydraulic structures.
Vice President Senior Water Resources Engineer
Senior Water Resources Engineer