Using GIS to Assess Parcel Suitability for Potential Park Locations

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Using GIS to Assess Parcel Suitability for
Potential Park Locations

• Matthew Mullenax, GISP
• Berkeley County Planning Commission

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Study Background

• 2006 Census estimates list Berkeley County as one
  of 100 fastest growing counties in U.S.
• Growth has had impact on variety of public
  services, notably parks and recreation.
• Berkeley County looking to develop long-range
  strategy for park land acquisition.
• GIS can be used to help locate potential park
  sites via suitability modeling.
• Pilot project performed on Martinsburg, WV.

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Suitability Modeling

• A measure of the relative usefulness of a land
  unit for some given purpose.
• Typically used to locate something.
• If designed properly, the model results in
  potential locations being identified and assigned
  a relative suitability score for the activity.
• Breaks a big problem down into smaller,
  easily-solved goals which are combined for a
  measure of suitability.

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Suitability Modeling and GIS
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Suitability Modeling and GIS

• Weighted combination is one method of suitability
  modeling.

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Suitability Modeling and GIS

• Weighted combination is one method of suitability
  modeling.
• Weighted Sum Tool available with ESRI ArcGIS 9.2
  Spatial Analyst extension license.

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Suitability Modeling and GIS

• Weighted combination is one method of suitability
  modeling.
• Weighted Sum Tool available with ESRI ArcGIS 9.2
  Spatial Analyst extension license.
• Three major steps must be completed before
  running the tool
• Select evaluation or utility scale.
• Set scale or suitability values for inputs.
• Assign weights to inputs.

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Building the model

• Appropriate evaluation criteria
• Population
• Existing parks
• Roads

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Determine suitability of each input

• Population high population is preferred
• Existing parks areas distant from existing
  parks preferred
• Roads close proximity to major roads is
  preferred

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1. Select evaluation or utility scale

• Evaluation or utility scale works to normalize
  all input raster datasets.
• A linear scale of 1 to 9 by 1 has proven to be
  workable.
• gt9 values difficult to visually comprehend lt9
  values can decrease sensitivity

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Range of Suitability Values on Utility Scale

• 1 lowest suitability
• 2 very low suitability
• 3 low suitability
• 4 moderately low suitability
• 5 moderate suitability
• 6 moderately high suitability
• 7 high suitability
• 8 very high suitability
• 9 highest suitability

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2. Set scale or suitability values for inputs.

• The cells of each input raster in the analysis
  are assigned suitability values from the utility
  scale.
• The assignment of suitability values for a single
  layer is called Single Utility Assignment (SUA).

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Population input

• Central Dispatch address locations
• Perform Density calculation
• Use Reclassify tool to assign suitability values
  on utility scale (1 to 9 by 1)

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Set scale values for Population input
9 11 15 8 7.9 10 7 6.2 7.8 6 4.8
6.1 5 3.6 4.7 4 2.5 3.5 3 1.6 2.4 2
0.52 1.5 1 0 0.51
Reclassify
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Existing Parks input

• Existing Martinsburg parks (9)
• Perform Distance calculation
• Use Reclassify tool to assign suitability values
  on utility scale (1 to 9 by 1)

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Set scale values for Parks input
9 gt 5280 feet 8 4621 - 5280 7 3961 -
4620 6 3301 - 3960 5 2641 - 3300 4 1981 -
2640 3 1321 - 1980 2 661 - 1320 1 0 660
Reclassify
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Roads input

• Major roads (Routes 9, 11, and 45, King and Queen
  Streets, Edwin Miller Boulevard, Tavern Road)
• Perform Distance calculation
• Use Reclassify tool to assign suitability values
  on utility scale (1 to 9 by 1)

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Set scale values for Roads input
9 0 660 feet 8 661 1320 7 1321 1980 6
1981 2640 5 2641 3300 4 3301 3960 3
3961 4620 2 4621 5280 1 gt 5280
Reclassify
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3. Assign weights to inputs

• Each input is weighted, or assigned a percentage
  influence, based on its importance.
• The total influence for all inputs must equal 100
  percent.
• Total Suitability (criteria1 weight1)
  (criteria2 weight2) ... (criterian
  weightn)

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3. Assign weights to inputs

• Each input is weighted, or assigned a percentage
  influence, based on its importance.
• The total influence for all inputs must equal 100
  percent.
• Total Suitability (criteria1 weight1)
  (criteria2 weight2) ... (criterian
  weightn)

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SUAs combined to create Multiple Utility
Assignment (MUA)

(10)
(45)
(45)
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Results in Suitability Map
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Implementing the Suitability Map by Parcel
Assessment
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Implementing the Suitability Map by Parcel
Assessment

• Parcel assessment conducted using Zonal
  Statistics as Table Tool.

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Implementing the Suitability Map by Parcel
Assessment

• Parcel assessment conducted using Zonal
  Statistics as Table Tool.
• Tool calculates a variety of statistics on values
  of a raster within the zones of another
  dataset.

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Using Zonal Statistics as Table Tool

• Zone Layer is Parcel data.
• Value Raster is MUA.
• Creates table of statistics joined to Parcel data
  by unique PIN.

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Parcel Assessment

• Parcels mapped by MAX suitability value.
• Use of MEAN causes smaller parcels to have higher
  values overall than larger parcels.

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Parcel Assessment (contd)

• Select all parcels with score gt 6.75.
• Five areas identified.
• First area apartment complex adjacent to school
  playground church ball field (Martins
  Landing).
• Second area apartment complex in commercial area
  (Courthouse Apartments).
• Third area in large, phased subdivision in
  recently annexed West Side area (The Gallery).
• Fourth area apartment complex with playground
  (Fountainhead Apartments).
• Fifth area Downtown.

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Parcel Assessment (contd)

• Inspect selected parcels ownership information,
  current use, etc. and determine feasibility.
• If parcels unfeasible, run new query using next
  highest suitability values and re-perform
  inspection on newly selected parcels.

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Study Limitations/Future Considerations

• Spatial accuracy of Roads and Address inputs in
  few small areas.
• Lack of separation between residential vs.
  non-residential addresses.
• Parks layer does not include school, church,
  and/or subdivision improved open spaces.
• County inholdings, right-of-ways, municipal
  boundary shape have potential to influence
  results.
• Method of weight determination not overly
  rigorous.
• Consider creating distance grid from all roads
  vs. only major roads.

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Acknowledgements

• Steve Catlett
• Martinsburg-Berkeley County Parks Recreation

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Questions?

• Matthew Mullenax, GISP
  GIS Coordinator
  Berkeley County
  Planning Commission 400
  West Stephen Street, Suite 203
  Martinsburg, WV 25401
  PH - [phone]
  
  FX - [phone]
  mmullenax_at_berkeleycountycomm.org