1 / 53

Classifying wetlands and assessing their functions:

Classifying wetlands and assessing their functions:. Using the NC Wetlands Assessment Method (NCWAM) to analyze wetland mitigation sites in the coastal plain region. Emily R. Burton Environmental Studies Graduate Student University of North Carolina, Wilmington May 5, 2008. North Carolina.

Download Presentation

Classifying wetlands and assessing their functions:

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Classifying wetlands and assessing their functions: Using the NC Wetlands Assessment Method (NCWAM) to analyze wetland mitigation sites in the coastal plain region. Emily R. Burton Environmental Studies Graduate Student University of North Carolina, Wilmington May 5, 2008

  2. North Carolina WAM! Wetland Assessment Method

  3. Geography of NC Coastal Plain • Inner and outer coastal plain ecoregions • Broad interstream divides • Gentle-sloping plains • Mineral-based, poorly drained soils • Cape Fear, White Oak, Neuse, Roanoke, Tar-Pamlico, and Chowan River Basins

  4. Aerial Image of North Carolina

  5. Land Use and Wetland Loss • Once contained approximately 95% of the state’s 6 million acres of wetlands • About 51% of the original wetlands in North Carolina had been lost or altered in some way • Between 1950 – 1980, approx. 42.2% of this loss was caused by agricultural activities

  6. Converting Wetlands to Agriculture • Removal of all vegetation and debris • Cutting drainage ditches 24-48” deep • Creating field crowns

  7. Prior Converted (PC) Cropland • Compaction of soils creates a plow-pan • NRCS declared PC as those lands that converted wetlands prior to December 23, 1985: 1. Do not flood more than 14 days during the growing season 2. Agricultural commodity 3. Not since been abandoned

  8. Definition of Wetlands • USACE 1987 Wetland Delineation Manual • 3 Parameters: 1. Hydrology – presence of water within the upper 12 in. for at least 5% of the growing season 2. Hydrophytic vegetation – > 50% wetland species. 3. Hydric Soils – formed under wet conditions long enough to develop anaerobic conditions in upper 12 in.

  9. Wetlands and their Importance • Swamps, marshes, bogs, pine flats, and floodplains • Water quality improvement, flood storage, groundwater recharge, shoreline erosion protection • Provide habitat for fish and wildlife • Opportunities for recreation and aesthetic appreciation

  10. Regulatory Protections • Clean Water Act, 1972 • Army Corps of Engineers • Section 404(b)(1) Guidelines: 1. Avoid filling wetland resources 2. Minimize adverse impacts 3. Provide compensatory mitigation

  11. No Net Loss of Wetlands • 1989, President George Bush Sr. • Reduce the amount of wetlands impacted • Restore and create new wetlands • Three ways to provide mitigation through the regulatory process: 1. Mitigation Banking 2. In-Lieu Fee Process 3. Permittee Process (on-site restoration, enhancement, and/or creation)

  12. Mitigation Banking • Early 1990s market- based instrument • Sponsor creates a “bank” of restored, enhanced, and /or created wetlands • Made credits available to developers to “buy” • Provides compensatory mitigation in advance of authorized impacts

  13. Mitigation Banking (cont.) • Sponsor submits a prospectus to the Corps and Inter-agency Review Team • Detailed plan of the bank site and success criteria • Mitigation Banking Instrument (MBI) provides the legal framework • Sponsor becomes responsible for providing mitigation for Corps permits and the long-term management and ecological success of the site.

  14. North Carolina Department of Transportation • 1990 ambitious road- building initiative • NCDOT responsible for compensating for an increasing amount of wetland losses • Increased project delays • Wetland mitigation needed to expand and become more pro-active

  15. In-Lieu Fee Process • 1997 North Carolina Wetlands Restoration Program (WRP) • Allows permittee to provide funds to an in-lieu-fee sponsor (WRP Fund) • First method of developing a per-acre cost of wetland restoration • Mitigating within the same river basin as impacts • Reporting and documenting of statewide wetland acreage losses and gains

  16. NC Ecosystem Enhancement Program (EEP) • 2003 MOA between the Corps, DOT, and DENR • More consistent and streamlined approach to mitigation • Implementation of large-scale watershed-based restoration efforts • 2004 accepted the transfer and responsibility of all of NCDOT’s off-site mitigation projects.

  17. Wetland Functional Assessment • Evaluating and tracking wetland function • Quantified based on acreage, numbers of planted trees survived, and hydrolo- gical data • Quality measured by the regulator’s best professional judgment (BPJ) • A new method of assessing wetland function was needed to make better and more defensible permit decisions

  18. North Carolina Wetland Assessment Method (NCWAM) • A team of experts gathered in 2003 to analyze approx 40 different existing methodologies • NCWAM Draft Manual was released in December of 2007 • Provides an accurate, consistent, rapid, observational, and scientifically-based field method

  19. Dichotomous Key to General North Carolina Wetland Types • 16 general wetland types in NC • Account for impacts by wetland type • Account for the inherent differences in function for each wetland type

  20. Bottomland Hardwood Forest

  21. Riverine Swamp Forest

  22. Non-Tidal Freshwater Marsh

  23. NCWAM Field Form • Level of function of wetlands based on ratings of indicators of function rather than their actual measurements • Evaluation of 22 metrics using observation, measurement, and BPJ • NC WAM rating calculatorconverts data into “High”, “Medium”, or “Low” functional ratings

  24. Wetland Functions • 11 Sub-functions • 3 Main functions: • Hydrology • Water Quality • Habitat • “High”, “Medium” and “Low” ratings – by separate function and overall

  25. Hydrology • Surface storage and retention • Subsurface storage and retention

  26. Water Quality • Particulate change • Soluble change • Pathogen change • Physical change • Pollution Change (combination of the first three)

  27. Habitat • Physical structure • Vegetation composition • Landscape patch structure • Habitat Uniqueness

  28. Site Selection for NC WAM Evaluation • 12 mitigation sites selected based on: 1. Geographical area – Inner and Outer Coastal Plain 2. Age of site development – 1993 – 2003; “Closed out” 3. Prior land use – PC cropland

  29. PC Restoration • The most “bang for your buck” • Historically supported hydric soils • Encompass larger areas • Minimal restoration design work and cost • Restored PC croplands = 2,176 acres

  30. Site Restoration • Drainage ditches plugged and/or filled • Discing, deep ripping, surface scarification

  31. Deep Ripping • Help increase permeability rates, surface roughness, hydrological retention, and improve vegetation restoration efforts

  32. Vegetation Planting • Within one year of site construction • Wetland species selected according to wetland type • Determined by a reference area • Saplings planted in rows

  33. Site Monitoring • Installation of ground water monitoring gauges • Vegetation remediation in first 1-2 years • Hydrology and vegetation success monitored for 4 – 6 years • Annual reports submitted to the Corps

  34. Methodology • Site restoration plans and monitoring reports from NCDOT, the Corps, and EEP • 8 NCDOT-owned, 4 privately owned mitigation banks • ArcView/ArcMap GIS mapping

  35. Tools for the Field • NCWAM forms and Draft Manual • Soil auger • Hand-held Global Position System (GPS) • Digital camera • Pocket rod • Soil surveys • Munsell Soil Color Charts • Compass

  36. Identifying Assessment Areas • Maps showing where hydrology had been restored and wetland vegetation planted • Walked and observed for changes • Identified a favorable, homogenous representation of a particular wetland type • Keyed out using the Dichotomous Key

  37. Site Evaluation • Completed NCWAM Form for the Assessment Area • Digital Photo Documentation • GPS recording of Lat/Long coordinates • 2-5 community types per site • 37 evaluations total

  38. NCWAM Results • 8/16 NC wetland community types represented: 11 Hardwood flats 9 Non-riverine swamp forests 6 Riverine swamp forests 4 Bottomland hardwood forests 4 Pine flats 1 Pine savanna 1 Floodplain pool 1 Non-tidal freshwater marsh

  39. Table 1: Functional Results of Wetland Mitigation Sites

  40. Table 2: Results of Wetland Functions for Individual Assessment Sites

  41. Table 2: Results of Wetland Functions for Individual Assessment Sites

  42. Table 2: Results of Wetland Functions for Individual Assessment Sites

  43. Table 2: Results of Wetland Functions for Individual Assessment Sites

  44. Results • 4 out of 12 mitigation sites rated “High” overall for all assessment areas evaluated: Scuppernong River Corridor Dismal Swamp Hidden Lake Gurley Tract • One rated “Low” overall: ABC

  45. Results (cont.) • 3 other sites had “Low” overall ratings • Alterations due to beaver activity • Lack of wetland functions due to presence of stream channelization, man-made berms, or soil compaction • Negative effects on all three wetland functions

  46. Discussion • Identifying the type of wetland community present • Different than what was originally planned • Post-restoration events substantially altered site conditions • For purposes of consistency  site identified as it appeared

  47. Conclusions • NC WAM has the ability to determine wetland functionality accurately • Hydrology “High” (75.5%) – first function to be replaced after a site is constructed • Water Quality “High” (67%) – relative to inundation duration, vegetation structure, and opportunity (surrounding land use) • Habitat “Low” (56.5%) – can take decades to hundreds of years to re-establish

  48. Lack of Opportunity • Nearby stormwater directed away from the wetland via ditches or storm drains • Stream channelization minimizes opportunity for over- bank flooding

  49. Restoration Methods • Standard method of restoring PC croplands works best for hydrology and water quality functions • Recommend introducing coarse woody debris to improve habitat functionality • “Less is better” (eg. ABC Site) • Creation is not preferred (eg. Haws Runs Site)

  50. NC WAM: A Validation for Success • Performance measures prior to NCWAM based on minimum standard: 1. Hydrology present at least 12.5% of GS 2. Coverage of hydrophytic vegetation at least 260 stems/acre • NCWAM examines a range of wetland functions covering a number of observable characteristics • Valuable and accurate tool for evaluating success of mitigated wetlands

More Related