Effects of landscape-based green infrastructure on stormwater runoff in suburban developments
Hondula, K., S. Woznicki, AND T. Jarnagin. Effects of landscape-based green infrastructure on stormwater runoff in suburban developments. US IALE, Asheville, NC, April 03 - 07, 2016.
This abstract describes a field study comparing landscape green infrastructure (GI) to traditional gray infrastructure with respect to their impacts on suburban hydrology. Rainfall-runoff characteristics of four catchments were compared with the hypothesis that rainfall-runoff ratios and hydrograph peaks would decrease under landscape GI.
The development of impervious surfaces in urban and suburban catchments affects their hydrological behavior by decreasing infiltration, increasing peak hydrograph response following rainfall events, and ultimately increasing the total volume of water and mass of pollutants reaching streams. These changes have deleterious effects on downstream surface waters. Consequently, strategies to mitigate these impacts are now components of contemporary urban development and stormwater management. This study evaluates the effectiveness of landscape green infrastructure (GI) in reducing stormwater runoff volumes and controlling peak flows in four subdivision-scale suburban catchments (1.88 – 12.97 acres) in Montgomery County, MD, USA. Stormwater flow rates during runoff events were measured in five minute intervals at each catchment outlet. One catchment was built with GI vegetated swales on all parcels with the goal of intercepting, conveying, and infiltrating stormwater before it enters the sewer network. The remaining catchments were constructed with traditional gray infrastructure and “end-of-pipe” best management practices (BMPs) that treat stormwater before entering streams. This study compared characteristics of rainfall-runoff events at the green and gray infrastructure sites to understand their effects on suburban hydrology. The landscape GI strategy generally reduced rainfall-runoff ratios compared to gray infrastructure because of increased infiltration, ultimately reducing the burden of development on downstream aquatic ecosystems.