Wetland Functional Assessment Guidebook - Alaska Department of

238 Pages·2003·3 MB·English

Wetland Functional Assessment Guidebook
Operational Draft Guidebook
for Assessing the Functions of Riverine and Slope River Proximal
Wetlands in Coastal Southeast & Southcentral Alaska
Using the HGM Approach
By:
Jim Powell, David D’Amore, Ralph Thompson, Terry Brock,
Pete Huberth, Bruce Bigelow, and M. Todd Walter
Prepared For:

State of Alaska, Department of Environmental Conservation
410 Willoughby Ave., Suite 303
Juneau, AK 99801
June 2003

Operational Draft Guidebook
for Assessing the Functions of Riverine and Slope River Proximal
Wetlands in Coastal Southeast & Southcentral Alaska
Using the HGM Approach
By:
Jim Powell Pete Huberth
Wetlands Program Coordinator Forester
AK Dept of Environmental Conservation Forestry Industry Consulting
Division of Air and Water Quality 6725 Marguerite Street
410 Willoughby Ave. Suite 303 Juneau, AK 99801-9431
Juneau, AK 99801-1795

David V. D'Amore Bruce Bigelow
Research Soil Scientist Hydrologist
USDA Forest Service, Pacific Northwest U.S. Geological Survey
Research Station Water Resources Division
2770 Sherwood Lane, Suite 2A Juneau, AK 99801
Juneau, AK. 99801

Ralph Thompson M. Todd Walter
Biologist / PWS (Former Position) Affiliate Professor
Juneau Regulatory Field Office University of Alaska Southeast
Regulatory Branch 11120 Glacier Highway
U.S. Army Corps of Engineers Juneau, AK 99801
Suite 106, Jordan Creek Center Senior Research Associate
8800 Glacier Highway Department of Biological &
Juneau, AK 99801 Environmental Engineering
Cornell University
Terry Brock Ithaca, NY 14853-5701
Soil and Wetland Scientist / PWS (retired)
USDA / U.S. Forest Service
Juneau, AK 99801
This document should be cited as Powell, J. E., D’Amore, D. V., Thompson, R., Huberth P., Bigelow, B.,
Walter, M. T., and Brock, T. “Wetland Functional Assessment Guidebook, Operational Draft Guidebook for
Assessing the Functions for Riverine and Slope River Proximal Wetlands in Coastal Southeast and Southcentral
Alaska Using the HGM Approach,” State of Alaska Department of Environmental Conservation June 2003 /
U.S. Army Corps of Engineers Waterways Experiment Station Technical Report: WRP-DE-__.
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Acknowledgments
The authors thank all of the individuals and agencies that made this project possible. The
development of hydrogeomorphic models requires extraordinary cooperation among many different
individuals with diverse knowledge and backgrounds. Expertise in wetland ecology, soil science,
hydrology, plant ecology, fish and wildlife biology, statistics, land use, and other disciplines is needed
to produce scientifically sound models that form the basis of the hydrogeomorphic (HGM) functional
assessment methodology. In addition, the building of an HGM model requires skill in personnel and
funding management as a project usually involves many agencies (state, federal, and local) and private
organizations. The agencies and groups providing direct funding, personnel, and logistical support for
this project include:
U.S. Environmental Protection Agency (EPA)
U.S. Army Corps of Engineers (COE)
USDA Forest Service, Alaska Region (USFS)
USDA Forest Service, Forestry Sciences Laboratory, Pacific Northwest Research Station (FSL)
Alaska Department of Environmental Conservation (ADEC)
Alaska Department of Fish and Game (ADF&G)
Alaska Department of Natural Resources (ADNR)
USDA Natural Resources Conservation Service (NRCS)
US Geological Survey, Water Resources Division (USGS)
NOAA National Marine Fisheries Services (NMFS)
EPA, Alaska Operations Office, provided the majority of the funding for this project through ADEC.
A great deal of field time and technical support was provided by local wetland experts including Ms.
Janet Schempf (ADF&G), Dr. K Koski (NMFS), Kevin Brownlee (ADF&G), Mr. Rick Noll (formerly
of ADNR), Mr. Mark Anderson (ADEC), Ms. Ann Leggett (HDR Alaska, Inc.), and Mr. Mark Jen
(EPA). Mr. Jack Gustafson and Mr. Dave Hardy (ADF&G) provided local knowledge and expertise
in Sitka and Ketchikan, Alaska. Chugachmiut Native Association also provided logistical support in
Port Graham and Nanwalik, Alaska.
Furthermore, the authors greatly appreciated the considerable talent and effort Dr. Mark Brinson, Mr.
Garrett Hollands, Dr. Lyndon C. Lee, Dr. Wade Nutter, and Dr. Dennis Whigham provided in terms of
field time and technical reviews of the initial draft guidebook.
Ms. Paula Hunt-Higgins, Ms. Katharine Lee, Ms. Karen Nakayama, Mr. Matthew Braun, and Ms.
Melissa Chaun of L.C. Lee & Associates, Inc. spent many hours providing logistics, editing,
formatting, and creating the initial draft guidebook. Mr. Mark Cable Rains, Mr. Kevin Featherston,
and Mr. Jeff Mason provided valuable technical expertise during the production phase of this
guidebook. Their assistance and patience with the authors was invaluable.
This “Operational Draft Guidebook” (guidebook) draws from the "Regional Guidebook for Assessing
the Functions of Low Gradient, Riverine Wetlands in Western Kentucky" for format and we thank Mr.
Bill Ainslie (EPA), one of its principal authors, for his generous advice and assistance.
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This guidebook also uses parts of "The Operational Draft HGM Guidebook for Wetlands on
Precipitation Driven on Discontinuous Permafrost in Interior Alaska" and "The Slope/Flat Wetland
Complexes in the Lower Kenai River Drainage Basin Using the HGM Approach Guidebook" for
format. We thank the authors of these guidebooks for their work and assistance.
Disclaimer
This document is a Operational Draft Guidebook developed specifically to assist in the application of
an HGM functional assessment model of riverine wetlands and slope river proximal wetlands in
Coastal Southeast and Southcentral Alaska. It is intended to be used in its present form consistent
with the National Action Plan to Develop the Hydrogeomorphic Approach for Assessing Wetland
Functions (Federal Register, August 16, 1996 (Vol. 61, No. 160) at page 42603). The Operational
Draft Guidebook will be used and reviewed for a two-year period by regulatory and resource agencies.
Other organizations and other parties will have an opportunity to use the Operational Draft Guidebook
during this two-year period and provide recommendations for improvement. After the Operational
Draft Guidebook has been used in the field for two years it may be revised incorporating comments
and corrections identified by the Guidebook Development Team. The revised Operational Draft
Guidebook will be reviewed and approved by the COE/WES as a Final Guidebook.

Jim Powell
Wetlands Program Coordinator
Alaska Department of Environmental Conservation
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Contents
__________________________________________________________
1. Introduction .....................................................................................................................................1
Purpose of this guidebook................................................................................................................................................1
Alaskan Context...............................................................................................................................................................2
2. Overview of the Hydrogeomorphic Approach .............................................................................4
Hydrogeomorphic Classification.....................................................................................................................................4
Identification, Definition, and Description of Functions.................................................................................................6
Reference Systems...........................................................................................................................................................6
Reference System Development......................................................................................................................................8
Assessment Models and Functional Indexes..................................................................................................................10
3. Characterization of the Riverine and Slope River Proximal Wetlands in Coastal
Southeast and Southcentral Alaska ............................................................................................13
Area of Applicability – Coastal Western Hemlock-Sitka Spruce Forest Ecosystem.....................................................14
Reference Domain for the Riverine and Slope River Proximal Subclasses...................................................................15
Established Reference Domain.................................................................................................................................15
Potential Reference Domain.....................................................................................................................................15
Summary of Dominant Features of Riverine and Slope River Proximal Wetlands.......................................................18
Description of the Riverine and Slope River Proximal Subclasses................................................................................20
Landscape Position...................................................................................................................................................20
Riverine Wetlands..........................................................................................................................................................23
Slope River Proximal Wetlands.....................................................................................................................................30
Hydrology......................................................................................................................................................................32
Soils...............................................................................................................................................................................33
Vegetation......................................................................................................................................................................34
In-Channel Bank Vegetation.....................................................................................................................................34
Off-Channel Forests at Reference Standard Sites -Structure and Species Composition...........................................35
Off-Channel Forests at "Other Reference Sites” - Structure and Species Composition...........................................36
Fish and Wildlife Resources..........................................................................................................................................37
4. Functions and Assessment Models for Riverine and Slope River Proximal
Wetlands........................................................................................................................................38
Comparison of Riverine and Slope River Proximal Functions......................................................................................39
Riverine and Slope River Proximal functions................................................................................................................39
List of Riverine Wetlands Functions.............................................................................................................................44
Description of Riverine Functions and Corresponding Functional Capacity Indexes (FCI)..........................................45
Riverine Hydrologic Functions......................................................................................................................................45
1. Channel Meander Belt Integrity..........................................................................................................................45
2. Dynamic Flood Water Storage..............................................................................................................................46
Riverine Biogeochemical Functions..............................................................................................................................47
3. Nutrient Spiraling and Organic Carbon Export..................................................................................................47
4. Particulate Retention...........................................................................................................................................47
5. Removal of Imported Elements and Compounds..................................................................................................48
Riverine Habitat Functions............................................................................................................................................50
6. Maintenance of In-Channel Aquatic Biota...........................................................................................................50
7. Presence of Coarse Wood Structure....................................................................................................................50
8. Maintenance of Riparian Vegetation...................................................................................................................51
9. Maintenance of Connectivity and Interspersion...................................................................................................52
Description and Scaling of the Riverine Model Variables.............................................................................................55
1. Median Particle Size-D50 (Vpebble-D50)..................................................................................................55
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2. Channel Bed Roughness (Vchanrough)......................................................................................................56
3. Embeddedness (Vembedded)......................................................................................................................58
4. Potential Coarse Wood (Vcwpot)...............................................................................................................58
5. In - Channel Coarse Wood (Vcwin)...........................................................................................................59
6. Log jams (Vlogjams)..................................................................................................................................61
7. Subsurface Flow into the Wetland (Vsubin)...............................................................................................62
8. Riparian Shade (Vshade)............................................................................................................................63
9. Alterations of Hydroregime (Valthydro)....................................................................................................63
10. Barriers to Fish Movement (Vbarrier)........................................................................................................64
11. Overbank Flood Frequency (Vfreq )...........................................................................................................65
12. Flood Prone Area Storage Volume (Vstore)...............................................................................................66
13. Stream Bank Soil Permeability (Vsoilperm)..............................................................................................68
14. Tree Basal Area (Vtreeba)..........................................................................................................................68
15. Total Vegetative Cover (Vvegcov).............................................................................................................69
16. Number of Vegetative Strata (Vstrata).......................................................................................................72
17. Land Use of Assessment Area (Vwetuse)...................................................................................................73
18. Watershed Land Use (Vwatersheduse).......................................................................................................76
Slope River Proximal Model.........................................................................................................................................78
List of Slope River Proximal Wetland Functions..........................................................................................................78
Description of Slope River Proximal Functions and Corresponding Functional Capacity Indexes (FCI).....................79
1. Dynamic Flood Water Storage Capacity....................................................................................................79
2. Subsurface Water Retention Capacity........................................................................................................79
Biogeochemical.............................................................................................................................................................79
3. Nutrient Recycling......................................................................................................................................79
4. Organic Carbon Export...............................................................................................................................80
5. Integrity of the Root Zone..........................................................................................................................80
Habitat...........................................................................................................................................................................80
6. Maintenance of Wildlife Habitat Structure.................................................................................................80
7. Maintenance of Plants.................................................................................................................................81
Description and Scaling of Slope River Proximal Model Variables..............................................................................83
1. Presence of Redoximorphic Features V(redox)........................................................................................83

2. Presence and Structure of the Acrotelm Horizon V(acro)..........................................................................84

3. Stream bank Soil Permeability (Vsoilperm)...............................................................................................85
4. Source of Water (Vsource).........................................................................................................................86
5. Subsurface Flow From the Wetlands (Vsubout)........................................................................................89
6. Overbank Flood Frequency (Vfreq)...........................................................................................................90

7. Flood Prone Area Storage Volume (Vstore)...............................................................................................92
8. Assessment Area Land Use (Vwetuse).......................................................................................................93
9. Adjacent Land Use (Vadjuse).....................................................................................................................94
10. Microtopographic Features V(micro)........................................................................................................96
11. Presence of Surface Water (Vsurwat).........................................................................................................97
12. Total Vegetative Cover (Vvegcov).............................................................................................................98
13. Number of Vegetative Strata (Vstrata).....................................................................................................100
14. Canopy Gaps (Vgaps)..............................................................................................................................101
15. Tree Basal Area (Vtreeba)........................................................................................................................102
16. Log Decomposition (Vdecomp)...............................................................................................................103
17. Coarse Wood in Slope Assessment Area (Vcwslope).............................................................................104

APPENDICES

Appendix 1 - Field Guide and Data Collection Procedures
Appendix 2 - Screenview of Electronic Spreadsheet for Calculating the Functional Capacity
Index (FCI)
Appendix 3 - Data Analysis and Array Sheets
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Appendix 4 - Guidebook Development
Appendix 5 - HGM INTERAGENCY MOU
Appendix 6 - Literature
Appendix 7- Glossary

LIST OF FIGURES
Figure 1. HGM Reference System Structure...........................................................................7
Figure 2. Use of the HGM Subclass Profile (Modified from the National
Wetlands Science Training Cooperative 1996).......................................................9
Figure 3. Structure of an HGM Model (Modified from the NWSTC 1996).......................11
Figure 4. Area of Applicability - Coastal Western Hemlock-Sitka Spruce Forest
Ecosystem..................................................................................................................14
Figure 5. Reference Domain Study Areas..............................................................................17
Figure 6. Juneau Area Reference Sample Sites.....................................................................18
Figure 7. Idealized Cross-Section Showing the Typical Relationship Between
Riverine and Slope River Proximal Wetlands.......................................................22
Figure 8. Rogen’s Stream Classification................................................................................24
Figure 9. Stream Classification Cross Reference..................................................................25
Figure 10. Stream Channel cross-section and measurements................................................27
Figure 11. An Example of a Course Wood Jam in a Reference Standard Site in SE
Alaska........................................................................................................................30
Figure 12. Average Particle Size of Reference Sites and Reference Standard Sites
vs. Cumulative Percent Finer..................................................................................32
Figure 13. HGM Assessment Area Diagram for Riverine Wetlands....................................75
Figure 14. HGM Assessment Area for Slope River Proximal Wetlands...............................87

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LIST OF TABLES

Table 1. Seven HGM Classes of Wetlands.............................................................................4
Table 2. Reference Wetland Terms and Definitions.............................................................6
Table 3. Reference Domain and Geomorphic Class Terms...............................................16
Table 4. Dominant Features of Riverine and Slope River Proximal wetlands in Coastal
Southeast and Southcentral Alaska.......................................................................19
Table 5. Key to Riverine and Slope River Proximal Wetlands in Coastal SE &
SC Alaska.................................................................................................................20
Table 6. Riverine Subclass Model Boundaries....................................................................26
Table 7. Slope River Proximal Subclass Boundaries..........................................................31
Table 8. List of Variables for Riverine and Slope River Proximal Wetlands..................41
Table 9. List of Riverine Wetland Model Variables...........................................................53
Table 10. List of Riverine Variables Organized by Data Collection Groups.....................54
Table 11. Relationship of Slope River Proximal Wetland Functions to Variables............82
Table 12. List of Slope River Proximal Variables Organized by Data Collection Groups83
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LIST OF PHOTOGRAPHS

Photograph 1. A typical reference standard riverine wetland in SE/SC Alaska.
Reference Site #5 (Fish Creek)............................................................................28
Photograph 2. A typical reference standard riverine wetland in SE/SC Alaska. -
Reference Site #5 (Fish Creek)............................................................................29
Photograph 3. An example of a course wood jam in a reference standard site in SE
Alaska....................................................................................................................30
Photograph 4. Typical River Proximal Slope Wetland in Coastal SE & SC Alaska .............31
Photograph 5. Representative size distribution of particles of Reference Standard Sites.....33

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