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Urban watershed modeling in Seattle, Washington to simulate hydrologic impacts of green infrastructure
Citation:
Barnhart, B., P. Pettus, Bob Mckane, J. Halama, P. Mayer, A. Brookes, AND K. Djang. Urban watershed modeling in Seattle, Washington to simulate hydrologic impacts of green infrastructure. Clean and Sustainable Water Technology Initiative Workshop, Corvallis, Oregon, August 06 - 07, 2018.
Impact/Purpose:
This abstract and poster will be presented at the inaugural Clean and Sustainable Water Technology Initiative Workshop that will be held at Oregon State University on Aug 6-7, 2018 (http://cbee.oregonstate.edu/water). The workshop will host scholars from academia as well as industry professionals interested in maintaining, preserving, and improving clean and sustainable sources of water for human use. This particular poster will showcase EPA ORD WED’s modeling abilities using the VELMA watershed model and will highlight green roof scenarios in Seattle, WA to better understand the hydrologic impacts of large-scale implementations of green infrastructure. Therefore, academics will benefit from the insights into urban watershed modeling, and industry professionals may learn about the hydrologic impacts of targeting large quantities of green infrastructure in urban environments.
Description:
Urban watersheds are notoriously difficult to model due to their complex, small-scale combinations of landscape and land use characteristics including impervious surfaces that ultimately affect the hydrologic system. We utilized EPA’s Visualizing Ecosystem Land Management Assessments (VELMA) model, which is a spatially explicit (i.e., gridded) ecohydrological watershed model, to simulate watershed-scale hydrologic discharge and nutrient concentrations for several urban stream systems in Seattle, Washington, including Thornton Creek, Piper’s Creek, Longfellow Creek, and Taylor Creek. A 1-meter land use classification is used to distinguish four cover types, including roads, buildings, trees, and grass. After model calibration and validation, we construct scenarios of hypothetical green roof implementations and simulate their impacts on watershed-scale discharge. Results show that VELMA is capable of simulating the impacts of targeted green infrastructure management practices to reduce peak stream flow events. These results suggest that VELMA can facilitate the prioritization of urban water infrastructure to improve water quality in urban streams leading to Puget Sound.