Trajectory economics: Assessing the flow of ecosystem services from coastal restoration

Monetized estimates of ecosystem services are increasingly cited as partial justification for a wide range of environmental restoration initiatives, yet parallel applications of these values in performance assessment have been limited. Incorporated into traditional economic models, such values can offer potential insight on programmatic efficiency and help to inform policy tradeoffs within and between competing methods. For this analysis, acreage trajectories and cost functions are developed for dredge- and diversion-based land reclamation methods in coastal Louisiana, USA. Benefit-cost models are constructed from which ecosystem service values are initially derived via break-even analysis and then specified to inform comparative case studies. Results indicate that the minimum service value required to offset project expenditures is typically higher for “natural” diversion-based restoration relative to “rapid” dredge-based methods under historic project conditions. Accounting for climatological and socioeconomic risks widens this gap, with benefit-cost ratios for dredge-based reclamation exceeding that of diversions in 16 benefit-cost simulations conducted over a 50-year project horizon. Taken together, these results highlight the influence of time and risk in the assessment of competing project alternatives, and suggest the need to reframe restoration efficiency in terms of the aggregate flow of ecosystem services, versus the per unit costs of terminal stocks.