Cumulative Effects of Low Impact Development on Watershed Hydrology in a Mixed Land-Cover System
Nahal Hoghooghi,
Heather E. Golden,
Brian P. Bledsoe,
Bradley L. Barnhart,
Allen F. Brookes,
Kevin S. Djang,
Jonathan J. Halama,
Robert B. McKane,
Christopher T. Nietch,
Paul P. Pettus
Affiliations
Nahal Hoghooghi
Oak Ridge Institute for Science and Education, c/o US Environmental Protection Agency, Office of Research and Development, National Exposure Research Laboratory, Cincinnati, OH 45268, USA
Heather E. Golden
National Exposure Research Laboratory, Office of Research and Development, US Environmental Protection Agency, Cincinnati, OH 45268, USA
Brian P. Bledsoe
Institute for Resilient Infrastructure Systems, College of Engineering, University of Georgia, Athens, GA 30602, USA
Bradley L. Barnhart
Western Ecology Division, National Health and Environmental Effects Research Laboratory, US Environmental Protection Agency, Corvallis, OR 97330, USA
Allen F. Brookes
Western Ecology Division, National Health and Environmental Effects Research Laboratory, US Environmental Protection Agency, Corvallis, OR 97330, USA
Kevin S. Djang
Inoventures LLC, Western Ecology Division, National Health and Environmental Effects Research Laboratory, c/o US Environmental Protection Agency, Corvallis, OR 97330, USA
Jonathan J. Halama
Western Ecology Division, National Health and Environmental Effects Research Laboratory, US Environmental Protection Agency, Corvallis, OR 97330, USA
Robert B. McKane
Western Ecology Division, National Health and Environmental Effects Research Laboratory, US Environmental Protection Agency, Corvallis, OR 97330, USA
Christopher T. Nietch
National Risk Management Research Laboratory, US Environmental Protection Agency, Cincinnati, OH 45268, USA
Paul P. Pettus
Western Ecology Division, National Health and Environmental Effects Research Laboratory, US Environmental Protection Agency, Corvallis, OR 97330, USA
Low Impact Development (LID) is an alternative to conventional urban stormwater management practices, which aims at mitigating the impacts of urbanization on water quantity and quality. Plot and local scale studies provide evidence of LID effectiveness; however, little is known about the overall watershed scale influence of LID practices. This is particularly true in watersheds with a land cover that is more diverse than that of urban or suburban classifications alone. We address this watershed-scale gap by assessing the effects of three common LID practices (rain gardens, permeable pavement, and riparian buffers) on the hydrology of a 0.94 km2 mixed land cover watershed. We used a spatially-explicit ecohydrological model, called Visualizing Ecosystems for Land Management Assessments (VELMA), to compare changes in watershed hydrologic responses before and after the implementation of LID practices. For the LID scenarios, we examined different spatial configurations, using 25%, 50%, 75% and 100% implementation extents, to convert sidewalks into rain gardens, and parking lots and driveways into permeable pavement. We further applied 20 m and 40 m riparian buffers along streams that were adjacent to agricultural land cover. The results showed overall increases in shallow subsurface runoff and infiltration, as well as evapotranspiration, and decreases in peak flows and surface runoff across all types and configurations of LID. Among individual LID practices, rain gardens had the greatest influence on each component of the overall watershed water balance. As anticipated, the combination of LID practices at the highest implementation level resulted in the most substantial changes to the overall watershed hydrology. It is notable that all hydrological changes from the LID implementation, ranging from 0.01 to 0.06 km2 across the study watershed, were modest, which suggests a potentially limited efficacy of LID practices in mixed land cover watersheds.
