wetland delineation special...
TRANSCRIPT
2017 Critical Methods Tom Nedland, WDNR
Wetland Delineation Special Considerations
Important Delineation Considerations
VEGETATION • Use the most up to date list
Important Delineation Considerations
VEGETATION • Populus tremuloides
and Rubus idaeus are FAC in NC/NE Regions of Wisconsin
Important Delineation Considerations
Be sure to consider nomenclature changes • Be sure to look up synonyms
• glossy buckthorn = Frangula alnus (R. frangula) • weeping willow= Salix x pendulina (S. babylonica) • crack willow = Salix x fragilis (S. fragilis)
• http://rsgisias.crrel.usace.army.mil/nwpl_static/index.html
VEGETATION
Important Delineation Considerations SOILS Field Indicators of Hydric Soil in the United States -version 8.0 • Includes all changes from latest errata. • Adds clarifying statements “within” replaced with < clarifies starting depth requirements
Important Delineation Considerations SOILS Use appropriate hydric soil indicators – per texture
Mineral Soils • A indicators (All mineral textures) • Sandy Textures = S Indicators
LFS or coarser (LS, FS, S)
• Loamy/Clayey Textures = F Indicators LVFS or finer (SL, L, SIL, SCL, CL, SICL,
SC, SIC, C)
Organic Soils • A indicators
Important Delineation Considerations SOILS Fun Test!!! • Which indicator(s) can be used for a diagnostic
layer that is 1. Loamy fine sand 2. Fine sandy loam
Important Delineation Considerations SOILS Fun Test!!! • Which indicator(s) can be used for a diagnostic
layer that is 1. Loamy fine sand (A and S) 2. Fine sandy loam
Important Delineation Considerations SOILS Fun Test!!! • Which indicator(s) can be used for a diagnostic
layer that is 1. Loamy fine sand (A and S) 2. Fine sandy loam (A and F)
Important Delineation Considerations SOILS Dig soils to adequate depth Regional Supplements
Recommend 20 inches. Hydric Soil Indicators Version 8.0 Recommends 20 inches Exceptions: May need to dig
deeper during dry season or in mollisols.
Dry Season = 24 inches to document dry season water table
Example soil profile. NRCS.
Important Delineation Considerations SOILS Understand Term Depleted Matrix • Value 4, Chroma 1 or 2, with >2% redox
concentrations • Value 5, Chroma 2, with >2% redox
concentrations • Value 5, Chroma 1, redox not required • Value >6, Chroma 1 or 2, redox not required
Depleted Matrix Value >5 chroma 1,
Value >6, chroma 2
with or without redox concentrations
4/1, 4/2, 5/2 with >2%
redox concentrations
Important Delineation Considerations HYDROLOGY Read and understand the user notes! • Geomorphic Position (D2) • Sparsely vegetated
concave surface (B8)
Important Delineation Considerations HYDROLOGY Geomorphic Position (D2) • Probably present if in a concave landscape position
and the other two parameters are present
Review user notes: not applicable in areas with functioning drainage systems or rapidly permeable soils
Important Delineation Considerations HYDROLOGY Geomorphic Position (D2) • Recommendation:
1. Rapidly Permeable Soils – do not indicate as present unless soil and vegetation parameters are present
2. Drainage Systems – do a hydrologic analysis if in a concave landscape position and hydric soils present
“Rapidly permeable” includes gravel, sand, and fine sand
Photo from Winnebago County Soil Survey
Knoll: Geomorphic Position Indicator generally not applicable
Photo from Winnebago County Soil Survey
Depression/Drainageway: Geomorphic Position Indicator generally is applicable
Important Delineation Considerations HYDROLOGY Sparsely vegetated concave surface (B8) • Concave surfaces with less than 5% ground cover
caused by long duration ponding during the growing season Review user notes: should contrast with adjacent
convex areas. • Recommendation:
1. Make sure sparse vegetation is due to ponding, not shading (compare concave to convex landforms)
2. Make sure vegetation is sparse – less than 5% ground cover
Sparsely vegetated concave area caused from long term ponding
Sparsely vegetated convex area caused from dense shading
Important Delineation Considerations HYDROLOGY Utilize Gage Data Where Available
Median Value = Determines the growing season flood elevation for 50/100 years. Any land found below the median elevation meets wetland hydrology and hydric soil indicators. Useful for large, dynamic systems
Important Delineation Considerations HYDROLOGY Stunted or stressed plants (D1 Indicator) • Use caution in harvested crop fields • Crop stubble can be very misleading. Suggest
not utilizing this indicator unless crops are still alive, or evidence of stunting/stress is justified with supplemental information. Eg. Explain in remarks how the
“stunted/stressed” stubble fits into the larger picture (landscape position, soil indicators, off-site review, etc.)
Important Delineation Considerations GENERAL
Antecedent Hydrologic Conditions • Recommend NRCS Method
• http://el.erdc.usace.army.mil/elpubs/pdf/wrap00-1/contents.pdf
• Statewide consistency • Not representative of site conditions? – Other sources
• USGS Waterwatch • Palmer Drought Severity Index
• Transfer information to data forms accordingly • In report, let reviewers know this information was taken into consideration
NRCS Antecedent Rainfall Documentation Method Important Delineation Considerations
NRCS Antecedent Rainfall Documentation Method Important Delineation Considerations
Important Delineation Considerations GENERAL
Antecedent Hydrologic Condition Example, Madison • Example: NRCS method not accurate (June 9, 2008)
March (1) April (2) May (3) Result Normal (2) Wet (3) Normal (2) Normal
Product Score (2) (6) (6) (14)
• 7.8 inches of rain fell between June 1 and June 8. • NRCS method not accurate under these conditions!!
Important Delineation Considerations GENERAL
Antecedent Hydrologic Condition Example, Madison • Other tools can help tell the tale (June 9, 2008)
USGS Waterwatch Data
Important Delineation Considerations GENERAL
Antecedent Hydrologic Condition Example, Madison • Other tools can help tell the tale (June 9, 2008)
Palmer Drought Index
Important Delineation Considerations GENERAL
Antecedent Hydrologic Condition Example, Madison • Let reviewers know how this information was taken
into consideration “Results of the antecedent precipitation analysis indicate the site had received normal rainfall during the three months prior to the wetland delineation. However, 7.08 inches of rainfall was documented near the site two days prior to the field investigation. Based upon the extreme amount of rain that occurred shortly prior to the field visit, it was assumed that primary wetland hydrology indicators would be present within the wetlands, as well as adjacent upland areas.”
Important Delineation Considerations GENERAL Document Growing Season • Most important for early or late season work • Document on data form or in report
• Green up (early) • Green growth on non-evergreen plants (late) • >41F at 12 inches below soil surface (late or early)
Growing Season Examples
Important Delineation Considerations GENERAL Document Growing Season • If field work completed outside of growing season…
• Perform a field visit the following spring • Verify accuracy of delineation (vegetation and hydrology)
Non-Growing Season Example UNLESS… Soil temp is >41F at 12 inches below soil surface.
Important Delineation Considerations GENERAL Adequately characterize a site • Take data points in Wet spot on soil mapping Wetness signatures on air photos Hydric or inclusion soils Distinct plant communities observed on air photos Mapped wetland area
Important Delineation Considerations GENERAL Adequately characterize a site
Important Delineation Considerations GENERAL Adequately characterize a site
Wetness Signature
Important Delineation Considerations GENERAL Adequately characterize a site
Wetness Signature
Mapped WWI
Important Delineation Considerations GENERAL Adequately characterize a site
Wetness Signature
Mapped WWI
Potential Wetland Soils
Important Delineation Considerations GENERAL Adequately characterize a site
Areas that need documenting
Important Delineation Considerations GENERAL Adequately characterize a site
100 feet
Important Delineation Considerations GENERAL Adequately characterize a site
100 feet
Why isn’t this area wetland?
How was this boundary established? Need paired points.
Why isn’t this area wetland?
Important Delineation Considerations GENERAL In difficult wetland situations, consider all data before reaching a decision Agricultural Sites Consideration 1: Has hydrology been altered?
• If not, soils may tell the story of the site Consideration 2: What does the preponderance of
information tell you? • Does offsite review indicate healthy crops and
drains have been documented? Often that is enough information to justify a field decision.
• Does offsite review indicate poor crop health, even though drains have been documented? That suggests the area is not effectively drained.
Important Delineation Considerations GENERAL In difficult wetland situations, make sure to consider all data before reaching a decision Agricultural sites Other Considerations:
• Are reference areas available? • What were the antecedent precipitation levels? • Does the volunteer vegetation in the questionable
area differ from the volunteer vegetation in obvious upland areas?
Questions