research project details
Project Title: Development of an HGM regional guidebook for wetlands of the Ridge and Valley Province of the central Appalachian Mountains
Investigator(s): Robert P. Brooks, Andy Cole, and Denice H. Wardrop
Sponsor: US Department of Army
Environmental Problem Addressed:
Wetland classification and functional assessment at regional and local levels.
Research Project Objectives:
Objective of this project is to develop a Regional Guidebook, targeting eight hydrogeomorphic (HGM) subclasses of wetlands, for use in classifying wetlands and assessing wetland function in the Ridge and Valley Province of the central Appalachian Mountains.
Summary:
The U.S. Army Corp of Engineer’s HGM Approach for Assessing Wetland Functions has been under development since the early 1990’s. HGM was developed in response to a need to better assess wetland functions as part of the 404 regulatory program. Under HGM, wetlands are classified based on their position within the landscape, source of water, and the dynamics of that water onsite. HGM relies on reference wetlands within a region to describe the normal range of variability of wetlands. An index of function is then calibrated to those reference wetlands to assess function.
On a national level, there are seven major HGM classes; however, HGM was designed to be regionalized and, accordingly, any particular part of the country can have different regional subclasses. Each class and subclass has specific functions and using these classes allows for a more accurate assessment of how a wetland would function given its place in the landscape. The goal of this project is to develop a Regional Guidebook for assessing wetland function in the Ridge and Valley Province of the central Appalachian Mountains.
The project will draw upon extensive data collected by the Penn State Cooperative Wetlands Center (CWC). Over a period of years, the CWC has collected data from approximately 100 reference wetlands. HGM models for riparian depression, slope, headwater floodplain, and mainstem floodplain regional subclasses have been developed by the CWC. The CWC will also develop models for fringing, headwater beaver-impounded, isolated depression, and mainstem depression subclasses. The eight models will be calibrated and verified over a wide geographic region and several years of data.
The Regional Guidebook, with its extensive literature review, calibrated models, and comprehensive sampling protocol covering eight HGM subclasses, will among the first for the northeastern United States. The Regional Guidebook will provide coverage of around 80-90% of the wetlands by type and area found in the Ridge and Valley Province, which comprises roughly 30% of Pennsylvania’s land area. Many HGM subclasses are highly interrelated on the landscape and this guidebook will help define those interactions and distinguish relevant functions. The guidebook, though developed from data gathered in central Pennsylvania, should have great applicability throughout the rest of the Ridge and Valley Province and have applicability in other ecoregions with minor modifications.