LID-SWM Practices as a Means of Resilience to Climate Change and Its Effects on Groundwater Recharge

Many surface water bodies have been severely degraded by runoff from the centuries of continuous human development without regard to the impacts of stormwater. Local governments are beginning to responsibly respond to the need for action about increased imperviousness by adopting local Low Impact Development (LID) ordinances. The purpose of this study was to evaluate the hydrologic abilities of LID development to: reduce peak runoff flow rates to the pre-development values; to infiltrate the recharge volumes mandated by current criteria; and to attenuate the impacts of extreme storm events. A numerical simulation was performed on a 4-hectare site for pre-development as well as residential development with Conventional and LID stormwater management design scenarios. Research results from four years of intense monitoring of LID systems at the University of New Hampshire Stormwater Center were integrated into these hydrologic models. Analyses were performed for hydrologic soil types A and C, for storms with recurrence intervals of 0.17-, 2-, 10-, and 100-years, as well as 2-, 10-, and 100-years adjusted for climate change. The results show that the LID site design: generated much lower runoff volumes than the Conventional and Pre-development site conditions; infiltrated more than the recharge volumes required by current regulations; and attenuated the impacts of extreme storms modified for climate change.