Spatial Analyst Module 3

1
Module 3 Objectives and Tasks
Intersect a Curvature Layer with a Soil Polygon
Layer

• Review Slope Curvature Model
• Create a Standard Hillshade
• Run Curvature Model
• Add\Symbolize\Evaluate Curvature Shapefile
• Intersect Curvature Shapefile and Soil Polygon
  Layer
• Export Soil\Curvature Intersect Data Table
• Summarize Slope Shape by Soil Map Units

For the Curvature Model to work properly, the
directory structure listed below must exist on
your computer. 1. c\temp 3.
c\home\data\spatial_analyst\shapefiles 2.
c\home\data\curvature 4.
c\home\data\spatial_analyst\tables
2
Review Slope Curvature Model
Layers data derived from Curvature Analysis
provides users with a picture of the overall
slope shape -- what areas are convex, concave and
linear.
This information allows us to separate erosional
and depositional surfaces this is significant
for soil genesis.
The layers created from the Curvature Model can
be used to assist in pre-mapping or to adjust
existing soil lines.
The intersection of curvature shapefiles and soil
polygons provides statistical information on
slope shape for each map unit. This could help
determine map unit composition.
3
Review Slope Curvature Model, cont.
The output from the Curvature Model is a grid.
Each cell value is a composite of 2 values that
represent slope shapes that are the perpendicular
(profile) and parallel (planar) to the slope. The
composite grid delineates the 9 different slope
shapes.
The first number represents values from the
profile grid (up slope) and the second number
represents the values from the planar grid
(across slope).
Profile grid (upslope) 1 Convex
3 Linear 5 Concave
Planar grid (across slope) 1 Concave 3
Linear 5 Convex
4
Create a Standard Hillshade
Open the sa_training ArcMap project, turn off
all layers and collapse all legends.
Hint To collapse or expand all legends ? hold
the ctrl-key and click on one of the legend
boxes. To turn on or off all layers, hold the
ctrl-key and click on one of the layer boxes.
5
Create a Standard Hillshade, cont.
To create a hillshade from the Spatial Analyst
Toolbar
6
Create a Standard Hillshade, cont.
In the Hillshade dialog box
Accept all other default values and click OK to
create
7
Create a Standard Hillshade, cont.
A magnification of the hillshade with contour
lines applied reveals the complexity of the slope
shapes.
The curvature model can provide acres and
composition of the different slope shapes.
For example, if Alpha soil occurs on
convex-convex positions in this area, the
curvature model can calculate the composition
of that slope shape.
8
Run Curvature Model
If Toolbox is not open, click on the Toolbox Icon
In ArcToolbox, click onSoils -- Spatial Analyst
Tools? Slope/Curvature Models? Curvature
9
Run Curvature Model, cont.
In the Curvature dialog box, select the Input
Raster (DEM) by clicking on the down arrow and
selecting your DEM (ex. bv83_clip)
An explanation of the output rasters and
shapefile is described in help.
Click OK to create a shapefile, and rasters of
profile, planar, and composite curves.
A slope shape shapefile (slope_shape) is
created in C\home\data\spatial_analyst\shapefile
s.A raster slope shape (curve) is created in
C\home\data\curvature. For this model to
work, create the same directory structure on your
computer.
10
Add\Symbolize\Evaluate Curvature Shapefile
To add the layer created by the Curvature Model,
click on the Add Data icon
Navigate to c\home\data\spatial_analyst\shapefil
es and select slope_shape.
To symbolize the slope_shape shapefile

• In the Data Frame window, double-click on
  slope_shape to open Layer Properties box

11
Add\Symbolize\Evaluate Curvature Shapefile, cont.
12
Add\Symbolize\Evaluate Curvature Shapefile, cont.
In the Layers Properties window under the
Symbology tab

• Click on Catagories ? Unique values

• Select Slp_shape for the Value Field

• Uncheck the all other values box

• Click on the Add All Values button

• Click OK

13
Add\Symbolize\Evaluate Curvature Shapefile, cont.
14
Intersect Curvature Shapefile andSoil Polygon
Layer
In ArcToolbox, click on Soils -- Spatial Analyst
Tools? Soil Intersect? Slopeshape-Mapunit Dissolve
This model intersects a slope shape shapefile
with a soil polygon layer. The model then
dissolves polygons based on inputs (MUSYM and
Slp_shape). Note If the output from this
model is used in an Excel worksheet, the dissolve
process is needed to reduce the number of records
(Excel can only have up to 65,536 rows).
15
Intersect Curvature Shapefile and Soil Polygon
Layer, cont.
In the Slopeshape-Mapunit Dissolve dialog box,
click on the Input Features drop down arrow and
add a soil polygon layer (ex. soil_clip) and a
slope shape shapefile (ex. slope_shape).
In the Dissolve Field window, check Slp_shape
and MUSYM. This will aggregate data based on
slope shape and map unit symbol.
Click OK to begin process
A shapefile named slpshape_mapunit_dissolve is
created in C\home\data\spatial_analyst\
shapefiles
16
Export Soil\Curvature Intersect Data Table
Click on the Add Data icon and add the layer
created by the Slope-Mapunit Dissolve Model
Navigate to -- c\home\data\spatial_analyst\shap
efiles and select slpshape_mapunit_dissolve
17
Export Soil\Curvature Intersect Data Table
In the Data Frame window

• Right-click on the slpshape_mapunit_dissolve
  layer

• Select Open Attribute Table

• Click on the Calculate Area/Acres icon

18
Export Soil\Curvature Intersect Data Table, cont.
1. If the Acres field is empty or has zeros,
click on the Options button and select Reload
Cache
2. To export your table, click on the Options
button and select Export
3. Browse to the C\home\data\spatial_analyst\tab
les directory and name the file soil_slpshape
4. Save the file to a dBase Table
5. Click Save
6. In the menus that follow, select OK to export
and No to add the table to ArcMap
19
Summarize Slope Shape by Soil Map Units
Start Microsoft Excel
In Excels Menu Bar

• Click on File ? Open

• In the Look in window, navigate to
  C\home\data\spatial_analyst\tables

• In the Files of type window, select dBase Files

• Click on the soil_slpshape file and click on
  Open

20
Summarize Slope Shape by Soil Map Units, cont.
To create a Pivot Table

• Click on Data

• In the drop down menu, select Pivot Table and
  PivotChart Report

21
Summarize Slope Shape by Soil Map Units, cont.
In the Pivot Table Wizard
22
Summarize Slope Shape by Soil Map Units, cont.
(Drop MUSYM and Slp_shape in here)
(Drop the Acres field here)
From the PivotTable Field List

• Drag and drop the MUSYM and Slp_shape fields
  into the Drop Row Fields Here box (make sure the
  MUSYM field is left of the Slp_shape field)

• Drag and drop the Acres field to the Drop Data
  Items Here box

23
Summarize Slope Shape by Soil Map Units, cont.
The resulting table displays the number of acres
by slope shape, for each map unit.
The table also lists the total acres by map unit.
24
Summarize Slope Shape by Soil Map Units, cont.
To calculate the percent composition for each
slope shape, by map unit

• Double-click on the Sum of Acres field

• Click on Options

• Under Show data as select of column

• Click OK to finish

25
Summarize Slope Shape by Soil Map Units, cont.
These values represent the of total acres for a
map unit slope shape. For example,
linear-linear slope shapes in map unit 010A,
account for 1.89 of the total acres. (1.89 of
total acres, not map unit acres) Also, 010A
accounts for 2.18 of the total acres
To view slope shape percentages for a single map
unit

• Click on the down arrow next to MUSYM

• Uncheck the box next to (Show All)

• Next, place a check next to any single map unit
  and click OK

26
Summarize Slope Shape by Soil Map Units, cont.
Results about 87 of 010A has a slope shape of
linear-linear.
To view results for other map units, click on the
down arrow, uncheck 010A, and place a check next
to a different map unit.