Using 2D Modeling to Improve Large-scale Urban Stormwater Modeling to Support Instream Water Quality Improvement

The English Coulee in Grand Forks, ND, USA is severely impacted by non-point source pollution from both agricultural and urban runoff, exacerbated by a flood protection diversion that was constructed following the catastrophic 1997 Red River flood that significantly altered the hydrology of the Coulee within the City. The greenspace corridor along the Coulee serves as a major recreational feature through the City with a major hospital, the University of North Dakota, and single family homes adjacent to the Coulee. Through a successful public outreach program in 2021, the City confirmed that City residents supported investing in the Coulee to improve water quality. Hydrologic (water levels and rainfall), water quality (multiple parameters), and sediment quality (multiple parameters) have been collected over the last few years. Because of the extremely flat topography, 2D rain-ongrid modeling with XP-STORM was required to accurately calibrate the hydrologic and hydraulic model.