Baltimore Ecosystem Study Cary Institute of Ecosystem Studies

2012 BES Annual Meeting Presentation and Poster Abstracts

High-resolution coupled-groundwater surface-water modeling of BES subwatersheds across a spectrum of development patterns
Barnes, Michael
Co-Authors: Michael Barnes, Claire Welty, and Andrew J. Miller

Abstract: As part of an NSF Water Sustainability and Climate project, we are using ParFlow, a distributed groundwater-surface water model, to simulate the interaction of urban development patterns and the hydrologic cycle. We are incorporating BES high-resolution topography and land use/land cover data derived from meter-scale LIDAR and orthoimagery. Use of data at fine scales permits the explicit modeling of urban landscape heterogeneity and enables us to capture the effects of urban land use dynamics on surface and subsurface flow paths. As a pilot demonstration, we have applied Parflow to DR5, a subwatershed in the headwaters of Dead Run. The model is gridded at 10 m x 10 m in the horizontal and 1 m in the vertical direction. This resolution adequately describes urban features such as building footprints and highways, while balancing performance considerations. The domain size is 3 sq km, with a total of 2,302,800 grid cells. Best estimates of hydraulic properties of impervious surfaces, soil, saprolite, and fractured bedrock have been incorporated into the model. NLDAS forcing data are used to specify precipitation and evapotranspiration. Initial spin-up, accomplished by draping the water table 5 m below the land surface and allowing the model to come to a quasi-equilibrium, reveals formation of both daylighted streams as well as streams buried in storm pipes, even though pipe locations are not specified in the model. Next steps include comparison of results to hydrologic responses of similar-sized watersheds in Dead Run and Red Run across a range of stormwater management conditions.