Assessment of a judgment‐based hydrogeomorphic wetland classification using long‐term hydrologic data

Abstract

Hydrogeomorphic (HGM) wetland classifications are becoming increasingly common but lack substantial review of assumptions behind those classifications. In this paper I compare an HGM classification of wetland sites developed by best professional judgment with a classification developed using long-term hydrologic data over those same sites. Forty-two wetlands, covering five hydrogeomorphic (HGM) subclasses, were sampled for over a decade in central Pennsylvania. Using median depth to water as the metric, four groups were identified through cluster analysis (created, riparian depression/slope, and two combinations of headwater/mainstem floodplains). The groundwater-fed sites (riparian depressions and toeof-slopes) were clearly separated by their more consistent source of water whereas other slopes and floodplain sites were less clearly defined. Long-term assessment of hydrology generally supported an HGM classification scheme developed under less stringent conditions and produced by best professional judgment but improvements in the assessment of drier sites is needed.

Inland wetlands in Africa: A review of their typologies and ecosystem services

“…Arising in part as a response to the limitations of Ramsar classifications, a hydrogeomorphic (HGM) approach to wetland classification has commonly been adopted in individual countries or regions (Cole, 2017). This approach focuses on the wetland's landscape setting and its detailed geomorphology, and how water flows through the site.…”

“…The advantage of the HGM approach is that it focuses explicitly on the physical properties and dynamics of wetlands and with an emphasis on wetlands as integrated physical systems (Shaffer et al, 1999;Brooks et al, 2011;Rivers-Moore et al, 2020;Singh et al, 2021). A disadvantage is that different HGM classifications may not be comparable between different users or regions (Whigham et al, 1999;Cole, 2016Cole, , 2017. In addition, it is not clear to what extent human activity within or utilisation of wetland resources are (or should) be considered as part of the HGM classification.…”

Quantifying the Flooding Regime and Vegetation Zone in Riparian Wetlands

“…), but unexpected ooding or submersion could impact the restoration efforts (Lee et al, 2017). While some studies have attempted to quantify the ood regime of wetlands using hydrogeomorphic (HGM) approaches (Gebo and Brooks, 2012;Cole, 2017), there is still a lack of research quantifying spatiotemporal characteristics of ood regimes, particularly in developing methodologies that eld technicians and designers can apply.…”

APEX simulation: Water quality of Sacramento Valley wetlands impacted by waterfowl droppings

“…These three variables are causally related, so information on one factor can be used to support another (CCW 1995). All three variables are used as indicators in numerous effective wetlands monitoring and assessment strategies including quantitative biological assessments (USEPA 2003) and hydrogeomorphic (HGM) functional assessments (Cole 2017). These have been used to assess wetlands at a variety of spatial scales (Collins et al 2007).…”

“…The HGM approach is also developed to facilitate longer term development of rapid assessment methods of estimating wetland functions (Brinson 1996). Also, the HGM approach is used for wetland classification (Brinson 1996;Brooks et al 2011) that can assess wetland hydrologic function without actually collecting field data (Cole 2017).…”