2002 Progress Report: Assessing an HGM-based Wetland Classification and Assessment Scheme Along a 1000 km Gradient of the Appalachian Mountains: Hydrology, Soils and Wetland Function

EPA Grant Number: R829497
Title: Assessing an HGM-based Wetland Classification and Assessment Scheme Along a 1000 km Gradient of the Appalachian Mountains: Hydrology, Soils and Wetland Function
Investigators: Cole, Charles Andrew , Brooks, Robert P. , Cirmo, Christopher P. , Wardrop, Denice Heller
Institution: Pennsylvania State University , The State University of New York at Cortland
EPA Project Officer: Packard, Benjamin H
Project Period: January 15, 2002 through January 14, 2005 (Extended to August 31, 2006)
Project Period Covered by this Report: January 15, 2002 through January 14, 2003
Project Amount: $973,301
RFA: Development of National Aquatic Ecosystem Classifications and Reference Conditions (2001) RFA Text |  Recipients Lists
Research Category: Ecosystems , Water , Aquatic Ecosystems


The overall objective of this research project is to determine the latitudinal extent of the hydrogeomorphic (HGM) classification and functional assessment process developed in Pennsylvania. A broad-based wetland classification and functional assessment approach would be of great utility in the development of defensible biocriteria in the Appalachian Mountain region.

The specific objectives of this research project are to: (1) determine the applicability of the HGM classification key (Cole, et al., 1997) and the functional assessment models (Wardrop, et al., 1998) to regions outside of Pennsylvania; (2) develop a set of reference wetlands in New York and Virginia, using the HGM key in Cole, et al., 1997. Additional sites will thus extend the current Appalachian wetland reference data set along a much larger latitudinal gradient (1,000 km) than currently exists in Pennsylvania; and (3) apply standard assessment protocols (Brooks, et al., 1996; Wardrop, et al., 1998) and models of function (Wardrop, et al., 1998) to all wetland sites to determine if both physical structure (e.g., hydrology, soils, plant communities) and inferred function are similar (within each HGM subclass) along this gradient.

Attributing functions to various wetland types is difficult without an organizing classification scheme. In recent years, there has been increasing focus on the development of theory and models based on the hydrogeomorphic (HGM) approach to wetland classification and assessment (Brinson, 1993; Brinson, 1995; Brinson, 1996). This approach classifies wetlands and assesses function based primarily on the location of the wetland in the landscape, the source of water for that wetland, and the dynamics of the water onsite. According to the HGM classification hierarchy, wetlands are grouped into national-level classes (Smith, et al., 1995), under which regional subclasses are defined (e.g., Cole, et al., 1997), and an analogous structure is followed for the development of functional assessment models. HGM has proved useful in organizing and understanding a variety of wetland data (e.g., Cole and Brooks, 2000a).

In Pennsylvania, a regional HGM classification and assessment protocol has been available for some time (see HGM key in Cole, et al., 1997). To date, the primary focus in Pennsylvania has been on the development of data (water, soils, plants, macroinvertebrates) and functional assessment models for four HGM subclasses (riparian depression, slope, headwater floodplain, mainstem floodplain). Specifically, a long-term hydrologic data set (> 8 years for some sites) has allowed for a deeper understanding of function in each of these subclasses.

Although a wealth of data has been collected relative to these subclasses in Pennsylvania, these data primarily have been restricted to wetland sites in central Pennsylvania. These four HGM subclasses have been described only from the Ridge and Valley Province of the Appalachian Mountains of central Pennsylvania. It is of great interest to ecologists and the regulatory community to determine if similar HGM subclasses occur further to the north and south of Pennsylvania, also located in the Appalachian Mountains. In other words, can we find similarly classified wetlands outside of the geographic range of the original data set for which the key and functional models were developed? More to the point, do these additional wetlands function in a comparable manner to their Pennsylvania counterparts? If so, this would allow for quick application of available functional assessment models and data rather than spend considerable additional effort in their development in other areas. This project would provide valuable information on the ability to transfer developed models across geographic boundaries.

Progress Summary:

New York

Adirondack Region. To date, nine Adirondack sites have been chosen, tentatively classified, and delineated, with two or three more to be chosen in the spring and summer of 2003. Most of the Adirondack sites are located within the property of the Huntington Wildlife Forest (HWF), which is operated by the State University of New York. In the summer of 2002, a team of three researchers worked on the establishment of the initial sampling grid networks, installation of wells, boundary determination, and soil sampling. Well logging is ongoing, and there are plans to download the initial 8-month water table data in spring 2003. Plans for the spring and summer of 2003 include the continued monitoring of the wells, and performing the tasks of the HGM protocol for vegetation, surveying, microtopography determination, and faunal inventory/habitat analysis. The complete protocol databases should be established by September for all of the Adirondack sites, and ongoing measurements of water table hydroperiod will continue for an additional 2 years. Intensive work on geographic information systems (GIS) map establishment and calibration of the models for testing in the Adirondack sites will be ongoing until the end of the project in the spring of 2005.

Catskills Region. In the summer of 2002, and in collaboration with Ms. Laurie Machung of the New York City Department of Environmental Protection (DEP), eight tentative wetland sites corresponding to the classes to be tested were examined, located with global positioning system technology, and mapped with the extensive database of the DEP laboratories. We plan on performing the final selection process, classification of sites, surveying, and the HGM protocol in the summer of 2003. A team of students and Principal Investigators (PIs) has been established to make the Catskills regions the priority New York region for the summer of 2003, with the goal of having all instrumentation and protocol work done by the fall of 2003 for both regions of New York.


The objective of this effort is to train field personnel to apply the Wetland Monitoring Protocols throughout the project area. Training of all associated personnel is an integral part of this work, as the PIs, graduate students, and the research technician are working across a broad latitudinal gradient and have not all been exposed to the same sampling protocols. Of the three main elements of the wetland monitoring protocol-plants, soils, and topography-plant identification clearly is the most difficult and time consuming. Unquestionably, identifying plants to species level can be problematic for even the most experienced botanist, and can result in lower sampling efficiency in the field. To increase the efficacy of plant identification during field monitoring, field personnel were given a 2½-day training course in wetland plant identification prior to the start of the field season (to be repeated in 2003). During the subsequent field monitoring season (approximately 6 weeks), the instructor accompanied the teams to offer additional assistance in plant identification. Plants that could not be identified in the field were collected and preserved. Collected plants were later identified by the students (with assistance from the instructor) during numerous keying sessions. In conclusion, after following the training regimen described above, field personnel overwhelmingly demonstrated their ability to follow the complete field protocol, including the plant identification presented previously.


The objective of this effort is to calibrate and refine the HGM functional assessment models for the Ridge and Valley Physiographic Province. Four subclasses have been selected for assessment in this project: headwater floodplains, mainstem floodplains, slopes, and riparian depressions. HGM functional assessment models originally had been developed for these four subclasses in the Ridge and Valley Physiographic Province, and were tested and significantly refined during the summer and fall of 2002. Significant documentation also has been developed, in the form of a regional HGM guidebook under a related project. Because not all subclasses perform the same wetland functions, the subclasses differ in the number of models developed for each. In summary, 10 models were developed for headwater floodplain, mainstem floodplain, and slope subclasses, and 7 models were developed for riparian depressions. A total of 42 sites in the Ridge and Valley Physiographic Province were used to calibrate the models and provide scoring criteria: 11 headwater floodplains, 8 mainstem floodplains, 9 riparian depressions, and 14 slopes. Across all functions, a total of 22 variables were calibrated. The models now are available for immediate use.


The objective of this effort is to develop a preliminary list of potential wetland sampling sites in the Jefferson and George Washington National Forests, Virginia. Our experience with applying National Wetlands Inventory digital data, and other remotely sensed data for inventorying wetlands in the unglaciated Ridge and Valley Physiographic Province, has shown that these data sources do not include the majority of wetlands occurring in the watersheds. To effectively sample wetlands for this project in the Jefferson National Forest, a better estimate of their general location is necessary. Inventory is particularly poor for forested wetlands that are difficult to identify in this ecoregion from high-altitude photographs. To remedy this situation, we previously had developed a best estimate of wetland occurrence for a number of watersheds in the Ridge and Valley Province in Pennsylvania. The model is derived from a combined set of GIS databases and a series of decision rules, applicable in an area of inclined bed geology. The model provides maps with areas of probable wetland location for each of four wetland types: slopes, riparian depressions, headwater floodplains, and mainstem floodplains. This process results in a map of the Jefferson National Forest, with narrow bands of area, wherein significant wetland area in each of the four HGM subclasses is the most probable.

The following information is used to predict the occurrence of headwater floodplain wetlands, mainstem floodplain wetlands, stratigraphic slopes, and topographic slopes (riparian depressions):

  • Floodplain wetlands on first and second order streams are predicted utilizing 100-year floodplain maps and formation contact information. Formations are now excluded from consideration when mapping these wetland types.
  • Floodplain wetlands on third and greater order streams are predicted utilizing 100-year floodplain maps only. Formations and formation contacts now are excluded from consideration when mapping these wetland types.
  • Slope wetlands are predicted utilizing formation contacts only.
  • Riparian depression wetlands are predicted by mapping intersections of valley bottom with slopes of greater than 15 percent on ridge sides.

The model requires an analytical set of rules based on characteristics of the underlying lithology; these characteristics previously had been developed for lithologies in various watersheds in Pennsylvania. However, the George Washington and Jefferson National Forests contain geology different from that of the original areas on which the model was based. Thus, the characteristics of the new units and their water bearing capacities needed to be determined before the model could be applied. The list of formations that requires coding currently is being assessed so that the model can be completed.

Future Activities:

Future activities will focus on, and be centered around, the following sites:

New York Sites. Summer 2003 will focus on establishment of the Catskills sites in southern NY, and performance of the HGM protocol on all the sites in the later part of the summer. All wells will be installed, soil samples taken, and surveying completed in the summer of 2003. Fall and spring of 2003-2004 will include initial database exploration and analysis, evaluation of Year 1 hydrology, and initial input of data to the models.

Pennsylvania Sites. This summer will be used to sample new Pennsylvania sites in the Ridge and Valley region. We expect to have completed sampling of 50-75 percent of all Pennsylvania sites by the end of September. The remaining sites will be sampled during 2004.

Virginia Sites. This spring and summer will be used to finalize the selection of new Virginia sites. We hope to completely finish site selection, and collect 50-75 percent of the data for the Virginia sites in 2003. We hope to finish that data collection in 2004. We hope to have all sites instrumented for water level monitoring in 2003.

Journal Articles on this Report : 2 Displayed | Download in RIS Format

Other project views: All 18 publications 3 publications in selected types All 3 journal articles
Type Citation Project Document Sources
Journal Article Brooks RP, Wardrop DH, Cole CA, Campbell DA. Are we purveyors of wetland homogeneity? A model of degradation and restoration to improve mitigation performance. Ecological Engineering 2005;24(4):331-340. R829497 (2002)
R829497 (2005)
  • Full-text: Science Direct Full Text
  • Abstract: Science Direct Abstract
  • Other: Science Direct PDF
  • Journal Article Cole CA, Brooks RP, Shaffer PW, Kentula ME. Comparison of hydrology of wetlands in Pennsylvania and Oregon (USA) as an indicator of transferability of hydrogeomorphic (HGM) functional models between regions. Environmental Management 2002;30(2):265-278. R829497 (2002)
  • Abstract from PubMed
  • Other: SpringerLink PDF
  • Supplemental Keywords:

    aquatic, classification, ecology, ecosystem, Mid-Atlantic, monitoring, PA, Pennsylvania., RFA, Scientific Discipline, INTERNATIONAL COOPERATION, Water, ECOSYSTEMS, Ecosystem Protection/Environmental Exposure & Risk, Aquatic Ecosystems & Estuarine Research, Water & Watershed, Aquatic Ecosystem, Monitoring/Modeling, Water Quality Monitoring, Environmental Monitoring, Terrestrial Ecosystems, Watersheds, anthropogenic stress, bioassessment, anthropogenic processes, wetlands, ecosystem monitoring, watershed management, biodiversity, conservation, diagnostic indicators, ecosystem indicators, biota diversity, hydrology, aquatic ecosystems, bioindicators, watershed sustainablility, water quality, biological indicators, ecosystem stress, watershed assessment, conservation planning, Appalachian Mountains, ecosystem response, aquatic biota, restoration planning, watershed restoration

    Progress and Final Reports:

    Original Abstract
  • 2003 Progress Report
  • 2004 Progress Report
  • 2005 Progress Report
  • Final