The Hydrogeomorphic Approach to assessing wetland functions, or HGM Approach, is a method to assess the functional condition (Smith 1995) of a specific wetland referenced to data collected from wetlands across a range of physical conditions. It utilizes a wetland classification system based on geomorphic position and hydrologic characteristics to group wetlands into seven different wetland classes as defined by Brinson (1993). The seven classes as defined by Brinson are:
The HGM Approach incorporates data collected from reference wetlands to scale mathematic models and provide an index from 0.0 to 1.0 to represent the level of wetland condition for each function. Regional Guidebooks are developed as a guide for assessing specific subclasses of the seven HGM classes of wetlands. HGM at the Subclass Level can be used to assess current wetland restoration success etc (Brinson 1996, Rheinhart 1997). Some guidebooks focus on a single subclass for a domain, while others include multiple subclasses. Asterisks on the HGM Guidebook Domain map indicate which guidebooks include multiple subclasses.
Web Date: October 1997