Impacts of Novel Stormwater Management on Groundwater Recharge

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Dr. Aditi S. Bhaskar has been awarded an NSF Earth Sciences Postdoctoral Fellowship to carry out a research and education plan at the United States Geological Survey. Novel forms of urban development aim to engineer systems that replicate natural hydrologic functioning. This includes preservation of near-natural groundwater recharge through infiltration of stormwater close to impervious surfaces where stormwater is generated. A small watershed in the Piedmont province of Maryland, USA is one of the first instrumented watersheds that was recently developed entirely with novel, distributed stormwater management techniques and is used as a case study for the work. This study seeks to understand how these alterations to the natural landscape impact subsurface flow systems and groundwater - surface water interactions. A network of field observations will be used, including measurements of streamflow, precipitation, hydraulic head, infiltration from and specifications of stormwater control measures, and hydraulic conductivity. The field data will inform the application of a three-dimensional, distributed hydrologic model, building on experience applying the same modeling system to other urban areas. The work will advance our understanding of how urban development alters hydrologic functioning. Mitigation strategies, such as distributed stormwater management, may transform the water cycle in previously unseen ways. Distributed infiltration of stormwater may result in groundwater recharge above pre-development levels. This means that water that might have evaporated or been transpired by plants in a natural system, or generated stormflow in a conventionally developed urban system, is instead redirected to groundwater pathways. The implications of these potentially major water cycle alterations are as yet unknown but may include significant changes to riparian ecology and biogeochemical cycling in ways that are not well understood. Understanding the effectiveness of these mitigation strategies in mimicking natural hydrologic functioning will provide a window into both the drivers of the natural hydrologic system and the landscape changes to which the natural system is most sensitive. Dr. Bhaskar will work with student researchers and will carry out education outreach to high schools in the area of the developed watershed for hands-on presentations about earth science, hydrology, groundwater, and connections to this research project.