The economics of sediment quality on barrier shoreline restoration.

This paper depicts a simulation-based assessment of sediment quality on the performance of dedicated dredging projects for barrier island restoration in coastal Louisiana, USA. The research involved the development and integration of two sub-models. In the first, geomorphic modeling was used to simulate sediment transport dynamics within a proxy barrier island template over a 50-year trajectory. The template was assumed to be nourished with one of two sources of dredged material: nearshore (NS) sediments of lower quality (smaller grain diameter, higher organic fines); or higher quality sediments from distal sources located on the Outer Continental Shelf (OCS). In the second model, agency project records and commercial bids were used to estimate project construction costs as a function of dredge material quantity, transport distance, and project target elevation. These sub-models were coupled within a net present value framework from which average annual break-even values for ecosystem services (EBEV) were derived as an efficiency metric for comparing the economic performance of NS- and OCS-sourced projects. Results indicate that in some cases, the physical resiliency afforded by even small increases in sand diameter (+4 µm d50) can translate to greater long-term economic viability (lower EBEV) for OCS-sourced sediment transported over longer distances. Moreover, projects constructed with much higher diameter OCS sediment (+44 µm d50) with low fines and transported over relatively long distances (200 µm, 5% fines, 15-20 miles) were found to be more cost-effective than all comparably-sized projects constructed with lower quality NS sediments obtained from proximal sources (156 µm, 20% fines, 3-5 miles). For some comparisons, this quality advantage yielded a lower EBEV for OCS-sourced projects with transport distances exceeding 30 miles. Under storm-punctuated simulations, these quality advantages were more pronounced, with greater physical and economic implications for earlier (Y5) versus later (Y20) occurring storms. Budgeting for dedicated dredging projects has traditionally centered on the value of sediment as a commodity, with a focus on material placement cost. The findings of this study, however, indicate that a more comprehensive accounting of sediment quality and performance is required to maximize the economic efficiency of coastal restoration spending.

Eliciting expert judgment to inform management of diverse oyster resources for multiple ecosystem services.

This study presents the most comprehensive set of ecosystem service provision estimates for diverse oyster-based resources to date. We use expert elicitation methods to derive estimates of five ecosystem services provided by oysters: oyster harvest (as indicated by oyster density), improved water quality (net nitrogen assimilation), shoreline protection (net erosion), and other fish habitat (blue crab and red drum density). Distributions are estimated for three distinct resources: on-bottom production, off-bottom farms, and non-harvested restoration/conservation efforts, under twelve distinct scenarios according to varying environmental conditions (eutrophication, sedimentation, and salinity regimes). Our expert-derived estimates of ecosystem services provide useful comparisons across oyster resources of both expected ecosystem service delivery levels and the amount of variation in those levels. These estimates bridge an information gap regarding relative performance of diverse oyster resources along multiple dimensions and should serve as a useful guide for resource managers facing competing interests.

Preventing land loss in coastal Louisiana: estimates of WTP and WTA.

A dichotomous-choice contingent-valuation survey was conducted in the State of Louisiana (USA) to estimate compensating surplus (CS) and equivalent surplus (ES) welfare measures for the prevention of future coastal wetland losses in Louisiana. Valuations were elicited using both willingness to pay (WTP) and willingness to accept compensation (WTA) payment vehicles. Mean CS (WTP) estimates based on a probit model using a Box-Cox specification on income was $825 per household annually, and mean ES (WTA) was estimated at $4444 per household annually. Regression results indicate that the major factors influencing support for land-loss prevention were income (positive, WTP model only), perceived hurricane protection benefits (positive), environmental and recreation protection (positive), distrust of government (negative), age (positive, WTA model only), and race (positive for whites).

Natural resource damage assessment for the Hebei Spirit oil spill: An application of Habitat Equivalency Analysis.

Sixteen oil spills occurred in Korea between 1995 and 2010, including the Hebei Spirit oil spill (HSOS) in 2007, the largest (77,857 barrels) in Korean history. Yet compensation for environmental damages has never been claimed under the International Oil Pollution Compensation Fund for any of these accidents, because there is no adequate natural resource damage assessment (NRDA) procedure and there are no internationally-admissible economic quantification methods established in Korea. The objective of this study is to propose a methodology to overcome these shortcomings. We propose the use of Habitat Equivalency Analysis, which has dominated the US NRDA process for oil spills, and apply it to the HSOS as a case study. A Base Case analysis estimates the compensatory costs of fishery habitat damages (34,703.5ha) with a 10-year recovery rate at $119.4 million. We also conduct sensitivity analyses under several alternative assumptions.