A Guidebook for Application of Hydrogeomorphic Assessments to Riverine Wetlands.

Abstract : The report outlines an approach for assessing wetland functions in the 404 Regulatory Program as well as other regulatory, planning, and management situations. The approach includes a development and application phase. In the development phase, wetlands are classified into regional subclasses based on hydrogeomorphic factors. A functional profile is developed to describe the characteristics of the regional subclass, identify the functions that are most likely to be performed, and discuss the characteristics that influence how those functions are performed. Reference wetlands are selected to represent the range of variability exhibited by the regional subclass in the selected reference domain, and assessment models are constructed and calibrated by an interdisciplinary team based on reference standards and data from reference wetlands. Reference standards are the conditions exhibited by the undisturbed, or least disturbed, wetlands and landscapes in the reference domain. The functional indices resulting from the assessment models provide a measure of the capacity of a wetland to perform functions relative to other wetlands in the regional subclass. The application phase of the approach, or assessment procedure, includes the characterization of the wetland, assessing its functions, analyzing the results of the assessment, and applying them to a specific project. The assessment procedure can be used to compare project alternatives, determine the impacts of a proposed project, avoid and minimize impacts, determine mitigation requirements or success, as well as other applications requiring the assessment of wetland functions.