Baltimore Ecosystem Study Institute of Ecosystem Studies

2015 BES Annual Meeting Presentation and Poster Abstracts



 
Urban base flow with green infrastructure
 
Bhaskar, Aditi
Co-Authors: Aditi Bhaskar, Dianna Hogan, Stacey Archfield

 
Abstract: A novel form of urban development, green infrastructure, aims to engineer systems that replicate natural hydrologic functioning. Green infrastructure includes the preservation of near-natural groundwater recharge via infiltration close to impervious surfaces where stormwater is generated. The instrumented study watershed is 1.11 km2 and located in Clarksburg, Maryland. Development occurred from 2004 to 2010 and resulted in the placement of 73 infiltration-focused stormwater facilities, including bioretention facilities, dry wells, and dry swales. We examined changes to annual and monthly streamflow during and after urban development (20042014) and compared alterations to nearby forested and urban control watersheds. We show that total flow and base flow increased in the study watershed during development as compared to control watersheds. We also found that the study watershed had slower storm recessions after development and a reduced seasonal signal during base flow conditions. These changes may be due to a combination of urban processes occurring during development, including reduction in evapotranspiration and the increase in point sources of recharge. Precipitation that may have infiltrated a forested landscape pre-development, been stored in soil moisture, and eventually been transpired by plants may now be recharged to groundwater and become base flow. A transfer of evapotranspiration to base flow is an unintended alteration to the urban water budget.