HGM Assessment
Decisions are made on an almost daily basis on whether or not to allow wetlands to be destroyed or altered. The process of making a decision about a particular wetland is neither straightforward, rapid, nor simple because of local, state, and national regulations.

In order for this process to work adequately, wetlands need to be assessed (i.e. evaluated) to characterize their ecological functions. While this process may sound simple, considerable effort and debate has gone into the process of wetland assessment. Unfortunately, there has not been nor is there currently any one procedure that everyone considers to be effective in evaluating wetland functions, even though a number of methods have been proposed since the 1970s.

Our laboratory has been involved in evaluating and applying an assessment method that has become known as the Hydrogeomorphic (HGM) approach. The method was initially developed through private and public efforts. We are particularly interested in how well the HGM method evaluates ecological functions. We have tested aspects of the method for one type of wetland that occur in the region where SERC is located.

We are currently conducting a study to determine if the HGM approach can be used to assess the ecological conditions of wetlands at the scale of an entire watershed. The Nanticoke Watershed Study is described in the Landscape Ecology portion of the website. The photographs on this page show teams of scientists visiting wetlands across the country for purposes of developing models that can be used in conducting wetland assessments.


A Black Spruce-dominated wetland on the Tanana River floodplain in central Alaska. The scientists in the foreground are sampling the overlying peat in order to examine soil development in systems where permafrost is a common feature.


The Pearl River in Arizona. Riparian ecosystems, including wetlands, associated with streams in the Southwest, are characterized by large annual variations in water supply. Southwestern riparian ecosystems are especially important habitats for many resident and migratory animals.

Scientists examine a water level recorder in a restored Prairie Pothole wetland near Jamestown, South Dakota. This team was part of a group developing models that would be used to evaluate the ecological conditions of depressional wetlands in the Prairie Pothole Region of the US. The site had been heavily impacted by cattle grazing prior to restoration of the prairie that surrounds the wetlands.

To learn more about the HGM approach, you can refer to our publications or visit the U.S. Army Corps of Engineers, Waterways Experiment Station.

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