Basis for Benefits Quantification

To provide meaningful input to decision-makers, it is important that computed benefits and costs reasonably reflect important changes that occur to the ecosystem as a consequence of the restoration actions. Ecosystems are not static; their condition changes over time in response to both natural and anthropocentric influences and change can be expected even absent any intervention. Consequently, the basis for evaluating project benefits is the change over time in the "state" of the ecosystem, as evidenced by key metrics reflecting the quality and/or quantity of ecosystem resources or services. The figure below shows this basis for comparison.

The baseline is referred to as the Future Without-Project (FWOP) condition, and is represented by the projected system condition over the planning timeframe (typically 50 years ) without the proposed restoration project . The incremental benefit afforded by any alternative is the area between the benefit curve for that alternative and the curve for the FWOP condition, and is referred to as the "output" in Corps planning. The net benefit is typically annualized by dividing the area between the curves by the number of years. In the figure below, Alternative 3 has a net benefit of 10,400 units (the area between Alt. 3 and FWOP curves) and an average annual benefit of 208 units (10,400 ÷ 50 yrs.).


Schematic representation of benefit curves for restoration alternatives. The shaded area represents the net benefits (i.e. "output") for Alternative 3. Note that the y-axis units could be dollars, habitat units, population size, or a reference-based index depending on the selected metrics and study design.