A synoptic assessment for prioritizing wetland restoration efforts to optimize flood attenuation

Abstract

The placement of wetland restoration projects in a landscape to optimize the functional performance of wetlands on a regional scale is often overlooked. To address this problem, the U.S. Environmental Protection Agency’s Landscape Function Project developed the synoptic approach to assign restoration priority to landscape subunits according to selected functional criteria. The approach provides a flexible, ecologically-based framework for allocating limited restoration-resources and preserving valued wetland functions on a landscape scale. We conducted a synoptic assessment of the Prairie Pothole Region of the northcentral U.S. to demonstrate application of the method for our assessment criterion—the marginal decrease in total downstream flood volume per restoration dollar. A criterion is often not directly measurable but can be represented by an index composed of measurements on related variables. In a synoptic assessment, these measured variables, referred to as indicators, are limited to variables for which data are existing, accessible, and uniformly available for the entire region. We developed a conceptual model to guide the development of an index of the assessment criterion. We then ranked landscape subunits based on index values and mapped the ranks to show relative priority for restoration among landscape subunits. We conducted a series of analyses to justify selection of indicators and some of our assumptions. The approach offers multiple options for processing and displaying information for use by wetland managers.