Improving the Decision-Making Process for Stormwater Management Using Life-Cycle Costs and a Benefit Analysis

Abstract

Stormwater management is a multiobjective decision-making process. Integrating life-cycle costs (LCC) and a benefit analysis with hydrologic modeling can enhance planning-level analyses by expanding available information for decision makers. In this study, two urbanized watersheds located in Los Angeles, California, and Denver, Colorado, are modeled using an integrated decision support tool for green to grey stormwater infrastructure. The primary goals are to compare capital costs to LCC and to explore the preference of green versus grey solutions using varying management criteria and a hydrologic benefit analysis. Results show that optimizing on capital costs alone produces qualitatively different results than optimizing on LCC, which are substantially higher. Additionally, a shift in relative cost order between stormwater control measure (SCM) types, when comparing capital costs and LCC, may misguide decision makers on which SCMs minimize cost while achieving regulatory compliance. Watershed-specific management criteria relevant to Ballona Creek (Los Angeles) and Berkeley neighborhood (Denver) result in a preference for greener solutions given hydrologic process benefits. The optimal solutions for these basins are determined by evaluating costs to the community and environment, comparing the hydrologic performance of varying SCMs, and ensuring the priorities of the individual watershed are met. Using a framework that integrates stormwater modeling, LCC, and a benefit analysis advances decision-relevant information for urban planners and water resource managers.