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GREEN STORMWATER INFRASTRUCTURE SUITABILITY MAPPING
Using GIS to Determine the Applicability of Green Stormwater Infrastructure
GIS MODEL PURPOSE
■ The MACC, with funding from the Community Foundation of the Holland Zeeland Area, developed
a Green Stormwater Vision for the Macatawa Watershed in 2017. The vision includes information
about types of green stormwater infrastructure, relationships between water quality and
transportation, a brief discussion of economics, and a strategy to implement the vision.
■ As part of this vision, a GSI suitability GIS model for the watershed was developed
■ In 2019, the GIS process was repeated to include all of Ottawa and Allegan Counties
PROJECT BACKGROUND
■ Target GSI installation to specific parcels to direct funding to the areas where it will have the greatest
positive impact
■ Provide the results to local planning commissions, developers, and engineers to use as an initial
screening tool for the inclusion of GSI in projects
GETTING STARTED
■ Reviewed and modified a GIS model completed for Berlin, MD
■ MACC model focuses on suitability for GSI involving infiltration
■ Criteria used in the MACC GIS analysis:
Hydrologic Soil Group
Natural Drainage Class
Slope
Lakes
Proximity to Structures
Link to study:
https://www.researchgate.net/publication/282230421_Creation_of_a_GIS_Based_Model_for_Determining_the_Suitability_of_Implementing_G
reen_Infrastructure_In_The_Town_Of_Berlin_Maryland
GSI SUITABILITY SCORING SYSTEM
SUITABILITY LEVEL / SCORECRITERIA HIGH (3) MEDIUM (2) LOW (1) NOT SUITABLE (0)HYDROLOGIC SOIL
GROUPA B C or D N/A
NATURAL DRAINAGE
CLASS
• Excessively drained
• Somewhat excessively
drained
• Well drained
• Moderately well
drained
• Somewhat
poorly drained
• Poorly drained
• Very poorly drained
SLOPE 2-4.9% 5-8% 0-1.9% >8%
PROXIMITY TO
STRUCTURESN/A N/A N/A Building footprint
Features with high suitability were assigned a value of 3
Medium suitability a value of 2
Low suitability a value of 1
Not suitable a value of 0
GSI SUITABILITY FORMULA
■ As the final step in this analysis, suitability will be determined at the parcel level using the
Raster Calculator, which adds together the scores of each overlapping raster layer in a cell
Hydrologic Soil Group Value + Drainage Class Value + Slope Value + Building Footprint Value + Lake Value
=
Green Infrastructure Suitability Score
SYSTEM REQUIREMENTS
■ ArcGIS Desktop 10.6.1 +
■ Spatial Analyst extension
■ ArcGIS Online account
DATA REQUIREMENTS
LAYER DATA TYPE
Area of Interest (AOI) Boundary Shapefile
Hydrologic Soil Group and Drainage Class Raster Files from ArcGIS Online
Parcels Shapefile
Lakes Shapefile
Elevation or Slope LiDAR
Building Footprints (Optional) Shapefile
DATA PREPARATION – HYDROLOGIC SOIL GROUP
■ ArcGIS Online - USA Soils Hydrologic Group
■ CLIP raster to your AOI
■ RESAMPLE to reduce the cell size to 4
■ RECLASSIFY according to suitability
Definitions Reclassification / Score
A = High Infiltration / Low Runoff 3 = High Suitability
B = Moderate Infiltration 2 = Medium Suitability
C = Slow Infiltration 1 = Low Suitability
D = Very Slow Infiltration 1 = Low Suitability
A/D, B/D, C/D 1 = Low Suitability
Hydrologic Soil Group – Before Reclassification Hydrologic Soil Group – After Reclassification
DATA PREPARATION – NATURAL DRAINAGE CLASS
■ ArcGIS Online – USA Soils Drainage Class
■ CLIP raster to your AOI
■ RESAMPLE to reduce the cell size to 4
■ RECLASSIFY according to suitability
Definitions Reclassification / Score
Excessively, Somewhat Excessively, and Well 3 = High Suitability
Moderately Well 2 = Medium Suitability
Somewhat Poorly and Poorly 1 = Low Suitability
Very Poorly 0 = Not Suitable
Drainage Class – Before Reclassification Drainage Class – After Reclassification
DATA PREPARATION - SLOPE
■ LiDAR data
■ Convert all layers to 4 foot resolution using RESAMPLE
■ Combine layers into one using MOSAIC TO NEW RASTER
■ CLIP new raster to AOI
■ Use SLOPE tool on output/clipped raster to get slope
■ RECLASSIFY slope according to suitability
Definitions Reclassification / Score
2 - 4.9% 3 = High Suitability
5 - 8% 2 = Medium Suitability
0 - 1.9% 1 = Low Suitability
> 8% 0 = Not Suitable
Mosiac LiDAR Slope – After Reclassification
DATA PREPARATION – EXCLUDING LAKES AND BUILDINGS■ UNION with AOI polygon
■ Open attribute table and select the line with the AOI and create layer from selected features
■ Alternatively, open edit session and delete lakes
■ Convert POLYGON TO RASTER
RASTER CALCULATOR
■ Performs an addition function in each cell where raster files line up
■ If there is no data in one of the raster layers, then there is no data in the output
Raster Calculator Output Raster Calculator Output – After Reclassification
ZONAL STATISTICS
■ Use ZONAL STATISTICS to determine the average suitability score per parcel
■ Calculates the average of all raster cells within each parcel
■ RECLASSIFY
PRIORITIZATION
■ Done separately from the suitability analysis
■ Which parcels are high priority?
– Government buildings, schools, churches
– Subwatershed
– Dependent on the organizations individual priorities and goals
ADDITIONAL INFORMATION
■ Available on our website: http://www.the-
macc.org/stormwater/green-infrastructure-suitability/
■ Green Stormwater Infrastructure Suitability Analysis
instructional guide
■ Green Stormwater Vision
■ PDF maps of all Allegan / Ottawa County cities and
townships
