Educational Module

1
Educational Module 2 Benthic Terrain
Classification

• Emily M. Larkin and Dawn Wright
• Dept. of Geosciences, Oregon State University
• September, 2004

2
Objectives

• On completion of the project, you should be able
  to
• Do a slope analysis.
• Use Raster Calculator to do simple analyses.
• Use Grid to process a short command sequence that
  is given to you.
• Define Slope, Bathymetric Position Index,
  benthic, standard deviation and benthic zones.

3
Benthic Terrain Classification

• Benthic of or pertaining to the seafloor.
  (e.g. A benthic animal lives on the seafloor.)
• Bathymetry can be classified into different zones
  based on what type of terrain it is.

4
Slope

• Slope is steepness of the landscape
• Percent Slope Rise / Run 100
• Degree Slope the measure of the slope angle

5
Bathymetric Position Index (BPI)

• BPI finds out where a pixel is in relationship to
  its neighbors.
• Raster calculator compares the position of a
  pixel to those around it.

6
Bathymetric Position Index

• BPI is calculated at a user-defined scale.
• The resolution of the grid the outer radius in
  the BPI equation
• Fine-scale BPIlooks at small features (e.g small
  crests on a large slope)
• Broad-scale BPIlooks at large features (e.g. the
  large slope)

7
Benthic Zones

• Divide bathymetry into 4 zones flats, slopes,
  crests and depressions
• Benthic zones have been linked to biodiversity
  (Karlson et al. 2004)
• Based on
• Slopegreater or less than 5
• Broad-scale BPIless than or greater than 1
  standard deviation from the mean
• WARNINGWhen you get to this part of the lesson,
  you must type everything correctly! Go slow and
  double-check.

8
Module 2

• Bathymetry from Pago Pago Harbor
• Slope Analysis
• BPI
• Benthic Zone Classification

9
Error Correction--

• Note On Page 12, Step 1 should read
• Add ppg5m84_neg. In the Spatial Analyst
• Step 1aMake sure the ppg5m84_neg grid is showing