Wetland Classification
NWI and LLWW = NWI+ Wetland Classification Systems
National Mapping Trends Analysis Wetland Evaluation U.S. Wetland Classification System Authors - Cowardin, Carter, Golet, LaRoe “Classification of Wetlands and Deepwater Habitats of the United States” (US Fish & Wildlife Service) 1977 (Operational Draft); 1979 final Federal Geographic Committee Data Standards for Wetland Classification and Mapping Classification Standard (1996) Wetland Mapping Standard (2009) Used for wetland mapping and trends analysis Hierarchal system Classification Hierarchy
Different levels based on knowledge or interest in wetlands and deepwater habitats System Subsystem Class Subclass Modifiers System
Five Systems: MARINE ESTUARINE RIVERINE LACUSTRINE PALUSTRINE
Subsystem
For Marine and Estuarine: SUBTIDAL and INTERTIDAL For Riverine: TIDAL, LOWER PERENNIAL, UPPER PERENNIAL, and INTERMITTENT For Lacustrine: LIMNETIC AND LITTORAL For Palustrine: none Class
Vegetated Classes FORESTED WETLAND SCRUB-SHRUB WETLAND EMERGENT WETLAND MOSS-LICHEN WETLAND AQUATIC BED Nonvegetated Classes ROCK BOTTOM or ROCKY SHORE UNCONSOLIDATED BOTTOM or SHORE REEF STREAMBED Subclasses - Examples
Emergent Wetland Persistent v. Nonpersistent Scrub-Shrub and Forested Wetland Broad-leaved Deciduous Needle-leaved Deciduous Broad-leaved Evergreen Needle-leaved Evergreen Dead Subclasses - Examples
Aquatic Bed Algal, Aquatic Moss, Rooted Vascular, Floating Vascular Rocky Shore/Bottom Bedrock, Rubble Unconsolidated Shore/Bottom Cobble-Gravel, Sand, Mud, Organic Reef Coral, Mollusk, Worm Modifiers
Water Regime: Tidal and Nontidal Water Chemistry: pH and Salinity/Halinity Soil: Organic and Mineral Special: Excavated, Diked, Impounded, Partly Drained, Farmed, Artificial, Beaver
ALSO Dominance Type and Regionalization Nontidal Water Regimes
Permanently Flooded Semipermanently Flooded Seasonally Flooded Temporarily Flooded Seasonally Saturated* Continuously Saturated* Lacustrine Limnetic Unconsolidated Bottom (water) and Palustrine Emergent Wetland (marsh) Palustrine Scrub-Shrub Wetland and Palustrine Unconsolidated Bottom (water) Palustrine Scrub-Shrub/Emergent Wetland and Palustrine Aquatic Bed/Unconsolidated Bottom Palustrine Forested Wetland (broad-leaved deciduous) Palustrine Forested Wetland (broad-leaved deciduous/needle-leaved evergreen) Lacustrine Littoral Aquatic Bed (rooted vascular) and Palustrine Emergent Wetland (cattail) Palustrine Emergent Wetland and Riverine Lower Perennial Unconsolidated Bottom (some Aquatic Bed) Attributes Not Included
Landscape Position Landform Water Flow Path Other Descriptors
Could interpret from NWI maps but not in classification or in digital database Some Questions
How many wetlands are there? What is the size range of wetlands? What is the average size of a given wetland type? How many wetlands are in various size classes? How much and how many occur along rivers? along streams? in lake basins? are “isolated”? are sources of streams? have inflow but no outflow? are connected to other wetlands or waters? What types of ponds are there and what is their extent? Needs for Enhancing the NWI Database
Better characterize wetlands for national wetland database Predict wetland functions Help assess significance of wetland losses and gains Predict functions expected from potential wetland restoration sites Hydrogeomorphic Classification
Developed by Brinson (1993) for wetland evaluation Emphasis on abiotic features More of “generic approach to classification and not a specific one to be used in practice” Reference wetlands for comparison of functions Used some Cowardin terms but defined differently (e.g., Riverine and Lacustrine) Adaptation of HGM
Use GIS technology to expand wetland classification and NWI database For watershed-based wetland characterizations and functional assessments Add descriptors LANDSCAPE POSITION LANDFORM WATER FLOW PATH WATERBODY TYPE Others Dichotomous Keys for Classification (Version 3.0) Landscape Position
Relationship between a Wetland and a Waterbody MARINE ESTUARINE LOTIC LENTIC TERRENE Landscape Position - Marine Landscape Position - Estuarine Landscape Position - Lentic Lentic (associated with lakes and reservoirs) Landscape Position - Lotic
RIVER STREAM Lotic (along rivers and streams and subject to overflow)
Landscape Position - Terrene Terrene (isolated, source of stream, or hydrologically decoupled from stream; latter types often are groundwater discharge sites)
Review Simplified Key for Landscape Position Landforms
Slope Island Fringe Floodplain (basin, flat) Basin Flat Peatland
Review Simplified Key for Landform Water Flow Path
Bidirectional-tidal (tidal ranges) Bidirectional-nontidal (throughflow, outflow, inflow, isolated – related to associated lake) Throughflow (perennial, intermittent, entrenched, artificial) Outflow (perennial, intermittent, artificial) Inflow Vertical Flow (“geographically isolated”) Paludified
Review Simplified Key for Water Flow Path Waterbody Types
River and Stream Gradients (tidal, dammed, intermittent, high, middle, and low) Lakes (e.g., natural, dammed river valley-reservoir, other dammed, excavated) Ponds (e.g., natural, artificial, beaver, sinkhole, farm, golf, prairie pothole, vernal, Carolina bay, playa, stormwater treatment, sewage lagoon) Estuary (e.g., drowned river valley, bar-built) Ocean (e.g., open, reef-protected, atoll, fjord) Other Descriptors - Examples
Headwater, Drainage-divide Delta, Barrier Island/Beach, Island Types, Former Floodplain Spring-fed Human-caused/impacted Floating mat Regional/local wetland types APPLICATIONS
Better Wetland Characterizations for Study Areas Use for Predicting Wetland Functions for: Watersheds or Larger Areas Historic and Recent Wetland Losses and Gains Potential Wetland Restoration Sites