Home 3. Identify Priority Wetlands 3b. Evaluate Vulnerability Evaluate Vulnerability

Evaluate Vulnerability

The goal of this step is to evaluate the potential for wetlands in your community to be impacted by future development or other land use activities.  The resulting data can be used as one ranking factor when prioritizing wetlands for conservation and/or restoration. This exercise involves identifying portions of the community with a significant likelihood of being developed in the future in order to assign a relative risk of future impacts to individual wetlands. As a result, wetlands that provide important functions and are highly vulnerable to impacts may be given a higher priority for conservation or other protective measure so there is no associated loss of function.

The basic idea is to determine how much growth is anticipated in your community over the next 20-30 years, and where that growth will likely occur.  Most communities can use available GIS data to answer these questions.  Table 3b.1 provides a list of potential data sources to use for this analysis.  This analysis can be supplemented with other non-GIS data sources such as population projections, comprehensive plans, and interviews with local planners.

Table 3b.1. Potential Data to Identify Future Development Pressure

Data layer

How do I use this data?

Where do I find this data?

Comprehensive or land use plan designation

Areas designated for future development would be assigned a higher development pressure.  The plan may also designate other lands uses, such as resource extraction, that would also be considered high vulnerability.

Local planning department

Zoning map

Areas zoned for high or medium density, commercial, industrial, institutional, and/or resource extraction would be assigned a higher development pressure.  Resource protection or conservation zones would have low development pressure.  The zoning map may have to be overlaid with existing development to extract future development pressure.

Local planning department

Infrastructure

Areas that have planned water/sewer service as well as areas with future road extensions have a higher likelihood of being developed

Local GIS, planning or public works department 

 

Urban growth boundaries

Areas designated for urban growth would be assigned high development pressure 

Local GIS, planning or public works department

Conservation easements

Lands protected by easement would have low development pressure

Local planning or natural resources department

Buildout analysis

Areas identified as ‘developed’ in future buildout would have high development pressure

State or regional planning department

Based on the available data, a GIS layer should be created that identifies areas of the community with a high probability of being developed.  If desired, the entire jurisdiction can be rated in terms of its development potential (e.g., high, medium, low).  This layer can then be intersected with the map of potential sites for conservation and/or restoration so that each individual wetland is assigned a value that represents vulnerability to development impacts.

The results of this step can provide a sense of how urgent the need is for local wetland protection in your community and should be incorporated into the ranking of potential sites for wetland conservation and/or restoration. The wetland functions, condition, boundaries, and potential stressors should then be verified through field assessments to further refine the prioritized list of wetlands for conservation and/or restoration.

 

 
Digitize
The process of converting features on a paper map into digital format using a trace methodology, which results in the creation of a spatial dataset.
Ecotone

A transition area between two adjacent, but different plant communities.

Indirect Wetland Impacts
Impact to wetlands caused by inputs of stormwater and pollutants generated by land development or other activities within the wetland CDA.
Direct Wetland Impacts
Wetland loss or degradation resulting from activities that occur within wetlands, such as dredging, filling and draining.  Activities that cause direct impacts are largely regulated through the federal and state wetland permitting process.
Stormwater Treatment Practices

A structural or non-structural practice designed to temporarily store or treat stormwater runoff in order to mitigate flooding, reduce pollution, and provide other amenities (also called a Best Management Practice – BMP).

Hydrogeomorphic
Factors that influence how wetlands function, including geomorphic setting, water source, and hydrodynamics.
Hydrogeomorphic
Factors that influence how wetlands function, including geomorphic setting, water source, and hydrodynamics.
Sinks
A cell or set of spatially connected cells that cannot be assigned flow direction in a raster elevation dataset. This can occur when all neighboring cells are higher than the processing cell or when two cells flow into one another. Sinks can indicate areas where water is likely to pond, but can also be an error in the dataset.
Facultative Wetland Plants
Species that usually occur in wetlands (approximately 67% - 99% probability), but also occur in non-wetland areas (approximately 1% - 33% probability).
Obligate Wetland Plants
Species that occur almost always in wetlands under natural conditions (greater than 99% probability), but which may also occur rarely in non-wetlands (less than 1% probability).
Interferometric Synthetic Aperture Radar (IFSAR)
A radar technique that uses two or more synthetic aperture radar (SAR) images to generate surface elevation using differences in the phase of waves returning to the satellite or aircraft.
Interferometric Synthetic Aperture Radar (IFSAR)
A radar technique that uses two or more synthetic aperture radar (SAR) images to generate surface elevation using differences in the phase of waves returning to the satellite or aircraft.
Light Detection and Ranging (LiDAR)

A remote sensing technique that measures properties of pulsed laser light reflected from objects to determine their position, velocity, and other information.

Light Detection and Ranging (LiDAR)

A remote sensing technique that measures properties of pulsed laser light reflected from objects to determine their position, velocity, and other information.

Light Detection and Ranging (LiDAR)

A remote sensing technique that measures properties of pulsed laser light reflected from objects to determine their position, velocity, and other information.

Digital Elevation Model (DEM)
A digital file consisting of terrain elevations for ground positions at regularly spaced horizontal intervals.
Digital Elevation Model (DEM)
A digital file consisting of terrain elevations for ground positions at regularly spaced horizontal intervals.
Hyperspectral Data

Information collected and processed from across the electromagnetic spectrum. Spectral signatures (unique “fingerprint” left by specific objects) enable identification of materials that make up a scanned object.

Remote Sensing
Gathering and recording information about objects without actual contact through the use of such techniques as photography, infra-red imagery, and radar.
Hydrophytes
A plant that grows wholly or partially submerged in water.
Blackspots
Areas on aerial photos that show up as dark blue, dark grey, or black and are indicative of saturated soil conditions.
Stereoscopic
The ability to see three dimensionally by using two views of a single object from slightly different positions typically through the use of an optical aid known as a stereoscope.
Hydric Soils
Soils that are saturated, flooded, or ponded for a long enough period during the growing season to develop anaerobic conditions in the upper soil horizons.
Hydric Soils
Soils that are saturated, flooded, or ponded for a long enough period during the growing season to develop anaerobic conditions in the upper soil horizons.
Hydric Soils
Soils that are saturated, flooded, or ponded for a long enough period during the growing season to develop anaerobic conditions in the upper soil horizons.
Hydric Soils
Soils that are saturated, flooded, or ponded for a long enough period during the growing season to develop anaerobic conditions in the upper soil horizons.
Hydric Soils
Soils that are saturated, flooded, or ponded for a long enough period during the growing season to develop anaerobic conditions in the upper soil horizons.
Hydric Soils
Soils that are saturated, flooded, or ponded for a long enough period during the growing season to develop anaerobic conditions in the upper soil horizons.
Hydric Soils
Soils that are saturated, flooded, or ponded for a long enough period during the growing season to develop anaerobic conditions in the upper soil horizons.
Hydric Soils
Soils that are saturated, flooded, or ponded for a long enough period during the growing season to develop anaerobic conditions in the upper soil horizons.
Geographic Information Systems (GIS)

A system that integrates hardware, software, and data for capturing, managing, analyzing, and displaying all forms of geographically referenced information.

Geographic Information Systems (GIS)

A system that integrates hardware, software, and data for capturing, managing, analyzing, and displaying all forms of geographically referenced information.

Digitize
The process of converting features on a paper map into digital format using a trace methodology, which results in the creation of a spatial dataset.
Minimum Mapping Unit

The minimum size or dimensions for features to be mapped as lines or areas for a given map scale.