Intro > HGM Assessment Guidebooks

Arkansas HGM Functional Assessment Guidebooks

In addition to knowing what kind of wetlands we have in Arkansas, in order to manage them well we need to know if they are healthy. That is the purpose of functional assessment. By comparing the characteristics of a wetland with those of reference wetlands, we may determine if the wetland is likely functioning up to its potential. The Hydrogeomorphic Approach to Assessing Wetland Function is a science-based tool for measuring wetland health, and requires that Regional Guidebooks be developed specific to the area in which the tool is to be used. This is so that a wetland is only compared to reference wetlands in its region, and not from other states or areas with intrinsically different character: it's to ensure that we compare apples to apples.

Arkansas' Regional Guidebooks are being developed with the same rigorous standards used on guidebooks throughout the country. The US Army Corps of Engineers' Engineer Research and Development Center (ERDC), Environmental Laboratory is publishing each of the five Arkansas Regional Guidebooks. This federal laboratory has been responsible for the national HGM effort, and has informed the Arkansas effort from the beginning.

Each Regional Guidebook contains descriptions of all wetlands classes, subclasses, and community types found in the Wetland Planning Area, including forested and unforested types. Each includes a brief overview of the major components of the HGM Approach, including the procedures recommended for the development and application of Regional Guidebooks. Each discusses the wetland functions, assessment variables, and functional indices used in the guidebook from a generic perspective, and then applies the assessment models to specific regional wetland subclasses and defines the relationship of assessment variables to reference data. The last chapter of each Guidebook outlines the assessment protocol for conducting a functional assessment of forested regional wetland subclasses in the Wetland Planning Region for which it was written.

The development of an HGM guidebook requires several steps. Reference wetland data must be collected for between 100 and 200 reference wetland sites per Wetland Planning Region, depending on its size and the number and diversity of its wetland subclasses. These data must be entered into a relational database, where secondary measures (e.g., basal area) can be calculated from the raw data (e.g., diameter at breast height (dbh) measurements). Functional profiles must be developed for each wetland subclass, and then functional models developed. Variable subindex curves are calibrated using the reference wetland data for each subclass, and finally the Guidebook itself is written, reviewed and published. EPA funding has been secured to complete the development and publication of all five Regional Guidebooks, and they are in various stages of completion.

Delta - The Delta Regional Guidebook is complete, and has been published by ERDC. Download Appendix D - Spreadsheets or download Appendix E - Spatial Data (ZIP Formats)

Coastal Plain - The Coastal Plain Guidebook is complete, and has been published by ERDC.

Ouachita Mountains and Crowley's Ridge - The Guidebook for these regions has been written and is currently in review at ERDC. We anticipate that it will be published in the Fall of 2006.

Arkansas Valley - The draft guidebook for this region is complete and in internal review. We anticipate submission to ERDC this summer and publication of this Guidebook in late 2006 or early 2007.

Ozark Mountains - The reference wetland data have all been collected and entered into the database. Functional profiles have been developed, and models and calibrated subindex curves are being generated. A draft guidebook currently being written. We anticipate publication of this Guidebook in late 2007.

Learn more about the HGM assessment approach

This page was last edited 4/14/06.

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