Recharge beneath low impact development and the effects of climate variability

Abstract

Groundwater resources in urban, coastal environments are highly vulnerable to human pressures and climate variability. Impervious surfaces often overflow sewage systems, prevent infiltration, and reduce recharge to aquifers. To mitigate these effects, cities worldwide are adopting Low Impact Development (LID) approaches that are hypothesized to increase infiltration and recharge rates to aquifers. The effects of LID on recharge rates are unknown, particularly in response to interannual variability of the El Nino Southern Oscillation (ENSO). Results from this study indicate recharge rates are enhanced by one order of magnitude beneath LID compared with an irrigated grass lawn and are greater during El Nino years. Recharge rates are projected to increase by 100 mm/year beneath LID and increase 6.9% under forecasted El Nino years as compared to current El Nino years. This work highlights the benefits of LID to capture and store stormwater during El Nino years, which can help urban planners manage above average water volumes introduced from climate variability.