GeoHAT: A Case study

(Powerpoint presentation linked here)

Inputs:

  • Region: South Fork Catawba
  • Habitat: NLCD = 42 (Evergreen)
  • Minimum patch size: 5 HA
  • Core area: Beyond 2 pixels (60 m) from edge
  • Cost surface: NLCD based, values 1 – 1000
  • Sub-network cost threshold: 7500 cost units

Step 0: Extracting base data

  1. Specify selection criteria from HU feature class: Subbasin = “South Fork Catawba”
  2. Creates a raster mask and polygon outline of selected subbasin
  3. Extracts the following rasters using the mask
    • NLCD (2006)
    • catchments (from NHD+)

 Step 1: Extracting habitat (via NLCD)

  1. Specify the NLCD habitat types that indicated habitat: Value = 42
  2. Extracts all pixels meeting the criteria to create
    • Habitat raster (habitat = 1; all other pixels = NoData)
    • Habitat binary raster (habitat = 1; all other pixels = 0)

Step 2: Creating habitat patches

  1. Boundary clean patches and remove clusters < 5 HA

Step 3. Creating patch based rasters

  1. Calculate cost distance from habitat (using NLCD based cost surface)
  2. Calculate cost distance from protected areas (LMCOS)
  3. Calculate Euclidean distance to edge (into patch area)
  4. Extract core patches (as patch areas beyond 60 m from edge)
  5. Create subnetworks as areas within sub-network cost threshold of 10000 cost units

Step 4: Calculating patch attributes

  1. Calculate patch geometry: Area, Perimeter, Shape index  as [4 * sqrt(A)]/p]
  2. Calculate core:area ratio
  3. Calculate minimum distance to protected area
  4. Calculate min/max/mean distance to patch edge (for sub-patch analysis)

Step 5: Calculating sub-network attributes

  1. Count of patches within
  2. Total habitat area
  3. Mean patch size

Step 6: Calculating patch connectivity (w/in a  sub-network)

  1. Create patch graph (cost-TIN based nodes and edges)
  2. Create least cost paths between patches from patch graph
  3. Calculate patch diameter, betweenness centrality, and closeness centrality
  4. Calculate patch graph summary (diameter at different connectivity thresholds)