Accounting For Uncertainty In Determining The Economic Value Of Green Infrastructure Investments

摘要

Green Infrastructure (GI) practices attempt to mitigate the impacts of urbanization through waterrnharvesting, infiltration, evapotranspiration, and reuse on a small-scale. Proponents of GIrnprograms for some time have justified their case based on the potential advantages in costeffectivenessrnand wider economic benefits compared to conventional ‘grey’ infrastructure.rnToday, a growing acceptance of GI as an integral part of an overall stormwater managementrnplans has elevated the need to ensure that public programs, especially if they are intended tornmeet regulatory requirements (e.g. Combined Sewer Overflow (CSO) Long Term Control Plan)rnmeet the objectives.rnUncertainties in GI performance, adoption rates, costs, and benefits can have significantrnimplications on whether and where a GI program makes sense for municipalities, water utilities,rnand watershed managers. The issues are particularly important for programs that include somerncost sharing because higher levels of public-supported costs reduce the balance to be paid byrnprivate entities and lead to higher rates of adoption.rnThis paper discusses the integration of engineering, economics, and risk analyses in a model forrnassisting in GI program decision making. Specifically, the paper proposes a methodology forrnquantifying this uncertainty, allowing decision making to precede with better information and atrna confidence the GI program is structured and targeted most effectively. Methods for quantifyingrnuncertainty, producing output (such as the graphic below) and interpretation are discussed alongrnwith several applications.