Sustainability Analysis of Climate Change Mitigation Measures to Support Community Adaptation against Compound Flooding

Abstract

Results from our recent social survey show that the residents of the City of Imperial Beach (IB) are interested in utilizing rain barrels, a rainwater harvesting (RWH) technique, which can provide flood mitigation and a decentralized water supply. IB experiences compound flooding from intense rainfall combined with sea level rise induced groundwater table rise and overtopping from high waves. A city-wide implementation of RWH has been modeled in the software PCSWMM, where simulated results show a reduction in usually flooded areas with the implementation of rain barrels. This study aims to use GaBi, an LCA software, to analyze the sustainability of the production, installation, and disposal of rain barrels. Currently, existing flood mitigation and stormwater management for the City of IB requires the use of heavy machinery to physically remove water from city streets, and routine pumping of stormwater. This study uses GaBi, to determine the global warming potential of (GWP) and human toxicity potential (HTP) of existing and proposed stormwater discharges and management strategies. The GWP and HTP of the existing situation is compared with a mitigation scenario where a portion of the stormwater is collected in rain barrels, thus (i) reducing need for routine pumping and water removal from streets and (ii) reducing the strain on the centralized water distribution system. Preliminary results show that implementing rain barrels in the Imperial Beach community significantly decreases GWP, but increases HTP. For instance, city-wide implementation of rain barrels, with the total collection of over 10 billion gallons of rainwater in 20 years, could lead to a saving of 29 million kilograms of Carbon Dioxide (CO2) equivalent.