Regional Guidebook for Applying the Hydrogeomorphic Approach to Assessing Functions of Forested Wetlands in the Mississippi Alluvial Valley.

摘要

The Hydrogeomorphic (HGM) Approach is a method for developing and applying indices for the site-specific assessment of wetland functions. The HGM Approach was initially designed to be used in the context of the Clean Water Act Section 404 Regulatory Program permit review process to analyze project alternatives, minimize impacts, assess unavoidable impacts, determine mitigation requirements, and monitor the success of compensatory mitigation. However, a variety of other potential uses have been identified, including the design of wetland restoration projects, and management of wetlands. This Regional Guidebook presents the HGM Approach for assessing the functions of most of the wetlands that occur in the Mississippi Alluvial Valley (MAV). It consolidates and extends the coverage provided by two previous guidebooks for the Delta Region of Arkansas and the Yazoo Basin of Mississippi. The report begins with an overview of the HGM Approach and then classifies and characterizes the principal indentified MAV wetlands. Detailed HGM assessment models and protocols are presented for five of those wetland types, or subclasses, representing most of the forested wetlands in the region other than those associated with lakes and impoundments. The following wetland subclasses are treated in detail: Flat, Low-Gradient Riverine Backwater, Low-Gradient Riverine Overbank, Isolated Depression, and Connected Depression. The appendices provide field data collection forms and spreadsheets for making calculations.