UERLA Report: Hydrologic Evaluation of Wolf Trap National Park for the Performing Arts

Gerenday, Sarah

Wolf Trap National Park for the Performing Arts (WOTR) is a 0.47 km2 national park located in Vienna, Virginia (Walsh et al. 2015). The park features outdoor performance venues, open space, and a forest with hiking trails. The park is situated within the Difficult Run watershed and contains two creeks: Wolf Trap Creek, which runs southeast to northwest through the park, and Old Courthouse Spring Branch (Courthouse Creek), which enters the park from the northeast and joins with Wolf Trap Creek. WOTR is surrounded by suburbs and bounded on the south side by the Dulles Toll Road. Runoff entering the park from the toll road and surrounding suburbs contributes to flow in the two creeks and erosion within the park. Given the continuing development of the watershed and the abundance of impervious surfaces in and around the park, attention has been paid to managing runoff. In 2012, the Dimple, a lawn and stormwater capture area, was converted to a native meadow with a high capacity for infiltration, while maintaining its bowl-like shape. In 2018, three bioretention basins and an oil water separator were installed around the maintenance yard to capture and treat runoff before it enters Wolf Trap Creek. In the summer of 2019 a project was undertaken at WOTR to provide insight on runoff, flooding, and erosion in the park. To this end maps and hydrologic models of the park and surrounding area were created. Mapping and geospatial analysis were done using ArcGIS. Hydrologic modelling was done using the United States Army Corps of Engineers’ Hydrologic Engineering Center – Hydrologic Modeling System (HEC-HMS). Maps and models were based on 1/9 arc-second digital elevation models (DEM) from the United States Geological Survey (USGS), soil survey data from the National Resource Conservation Service (NRCS), the 2016 Virginia Land Cover Dataset from the Virginia Geographic Information Network (VGIN), the Fairfax County Stormwater Infrastructure interactive map, various surveys and construction plans on file at WOTR, and field observations.