Towards the inclusion of greenhouse gas fluxes in the carbon footprint of vegetated WSUD

Rapid global urbanization has resulted in more impervious surfaces within urban areas, which has caused additional pollutant loads on stormwater control systems. Water sensitive urban design (WSUD) systems have been developed to reduce the environmental impact on urban ecosystems by reducing the pollutant loads generated in and passed out of the catchment. Stormwater runoff quality and quantity have been well studied in urban catchments, while the ecosystem services and disservices of WSUD have received less attention. During the last decade, the impact of climate change has received a great deal of attention by the general public and decision makers. The carbon footprint is a useful indicator of the global warming potential (GWP) for urban infrastructure. Using a whole of life cycle thinking approach for the carbon footprint, four separate phases are identified, namely material production, construction/installation, operation and maintenance, and end-of-life phases. In spite of the attention on carbon embodied in these phases, the greenhouse gas (GHG) emissions have not been adequately recognized as a part of the carbon footprint of these systems. This paper identifies the importance of the GHG fluxes from vegetated WSUD basins and presents a conceptual approach to their inclusion in the life cycle carbon footprint. It has been shown that the estimation of carbon footprint just within the life cycle phases underestimate the total carbon footprint by ignoring the GHG fluxes. Despite the scarcity of available data on vegetated WSUD basins, the direct GHG fluxes over the life span of the vegetated stormwater basins can contribute to a large amount of carbon to the environment.