National Wetlands Inventory Mapping In Vermont Ralph Tiner, Regional Wetland Coordinator U.S. Fish...
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Transcript of National Wetlands Inventory Mapping In Vermont Ralph Tiner, Regional Wetland Coordinator U.S. Fish...
National Wetlands Inventory Mapping In Vermont
Ralph Tiner, Regional Wetland CoordinatorU.S. Fish and Wildlife Service
Northeast RegionHadley, MA
Background
National Program 90% of coterminous
US mapped 50% digitized
Regional Status 12 of 13 states
mapped Updating in progress
on a FWS priority basis and where outside funding is received
Purpose of Mapping
To inventory wetlands across the nation for natural resource conservation purposes
To identify and classify larger wetlands based on photointerpretation (recognizing limitations inherent in this approach)
To report on the status and trends of US wetlands and for states as mapping is completed
The NWI is not designed to map all the wetlands in any locality – that would require on-the-ground surveys applying wetland delineation techniques
Limitations of Photointerpretation for Mapping Wetlands
Photo Scale Seasonality (environmental conditions at time
of photo capture) Photo Quality Wetlands that are difficult to photointerpret
Photo Scale vs. Area
Scale Area In One Square Inch
1:80K 1020 acres
1:58K 540 acres
1:40K ~250 acres
1:24K 92 acres
1:12K ~25 acres
Photo Scale vs. Mapping Unit
Photo Scale vs. Target Mapping Unit 1:80,000 = 3-5 acres 1:58,000 = 1-3 acres 1:40,000 = 1 acre 1:24,000 = 0.25-0.50 acre 1:12,000 = 0.10 acre
1:80K vs. 1:58K
1:40K vs. 1:24K
1:24K vs. 1:12K
1:80K vs. 1:40K
1:80K vs. 1:12K
Photo Scale vs. # of Photos
Scale # of Photos/Quad #Photos/VT*1:80,000 1 1601:58,000 1.5 2401:40,000 4 6401:24,000 20 32001:12,000 42 6720
*Estimates based on 58 sq. mi/quad and Vermont land surface area.
May be approx. 220 quads (1:24K) covering the state
Pen Width vs. Ground Distance
Earlier maps were hand-drawn, so pen-width was a factor.
Scale 000 (0.25mm) 0000 (0.18mm)
1:80K ~67ft ~50ft
1:58K 48ft 34ft
1:40K 33ft 23ft
1:24K 20ft 14ft
1:12K 10ft 7ft
Scale Limits on Wetlands
Not simply acreage dependent Relates to shape
one-acre block vs. one-acre linear Relates to easy or difficulty of
photointerpretation of type
Wetland Type
Easy to identify types Marshes, bogs, seasonally flooded swamps,
ponds Harder to identify types
Drier-end wetlands Evergreen forested wetlands Temporarily flooded wetlands Wetlands on slopes (seepage)
Seasonality
Environmental Conditions Leaf on vs. Leaf off Spring vs. Fall (leaf off) Ambient weather Water tables and flooding Extreme flooding vs. droughts Snow and ice
Photo Quality
Emulsion Black and White (panchromatic) True Color Color Infrared
Resolution Processing (over vs. under exposed) Date (best available at 1:40K or smaller; now
use DOQ/DOQQ)
Original NWI Maps for Vermont
1:80,000 CIR October 1977 Target Mapping Unit = 3-5 acres Inventory done in late 1970s/1980. Mapping Procedures
Photointerpretation Limited Field Work Consultation with Soil Surveys? (No hydric soils
lists/indicators) Regional QC (spot checking) National QC (spot checking)
NWI Results vs. Hydric Soils
NWI
220,000 acres
3.7% of the state
Soil Data
341,000 acres
5.5%
Updated NWI Mapping
1:40,000 CIR 1992-1994 Target Mapping Unit = 1 acre Mapping Procedures
Edit original NWI data Photointerpretation Limited field checking Consult with soil surveys (interpretation) Regional QC (entire photo) National QC (automated verification)
Status of Updates in Vermont
New Mapping Procedures (2006)
Edit existing NWI data Photointerpretation on-screen
DOQ or DOQQ base Limited field checking FWS QC, automated verification Add undeveloped hydric soil map units FWS QC, automated verification
Enhanced NWI
Current NWI database Add other descriptors:
Landscape Position Landform Water Flow Path Waterbody Type
Use data to predict wetland functions
LLWW Descriptors
Landscape Position Lotic, Lentic, Terrene
Landform Floodplain, Basin, Flat, Fringe, Slope
Water Flow Path Inflow, Outflow, Throughflow, Bidirectional
Flow, Isolated Waterbody Type
Pond and lake types, impounded rivers, etc.
Functional Assessment
9 Functions for Inland Wetlands Surface Water Detention Streamflow Maintenance Nutrient Transformation Sediment Retention Shoreline Stabilization Fish and Shellfish Habitat Waterfowl/Waterbird Habitat Other Wildlife Habitat Conservation of Biodiversity
Updated NWI - Highlights
Smaller wetlands Refined boundaries Incorporates more hydric soil map units Can be enhanced to be more descriptive After enhancement, can use for preliminary
functional assessments Still will not map all wetlands – need ground
surveys applying delineation procedures to do this; potential vernal pool mapping through remote sensing