ESRI ArcGIS 9.2
Student Guide
Landslide Susceptibility
Analysis – Part II
Ann Johnson
Higher Education Solutions Manager
ajohnson@esri.com
Copyright
© 2003-2005 Environmental Systems Research Institute, Inc.
1
GIS Landside Susceptibility Analysis
ArcGIS 9.2 – Part II
This project study area is in San Bernardino County, California, which has been prone to
mudflows and landslides due to several factors. It is also an area that has been affected by
wildfires – the most recent of which occurred in October 2003. We would like to see if we can
determine what parts of the study area are more susceptible to slides.
The exercise uses real-world data and methods to look at some possible analysis models
to determine landside susceptibility including slope, aspect, vegetation and other possible factors.
In this project you use Digital Elevation Data (DEM) to derive slope and aspect datasets. These
datasets will be combined with other data to find areas with high slide susceptibility. The values
and models for determining Landside Susceptibility are for educational use only and should not
be used to determine slide hazards or areas safe from landslides as there are many factors that
are not considered in this exercise. This continues using the project from Part I.
Creating a ModelBuilder model to automate the
analysis from Part I
ModelBuilder creates a flow process diagram that contains all of the input data, functions and
output data that you manually created in the above analysis.
Creating a model for your project gives you the ability to: (1) share the model with other users,
(2) use the same model in other regions with their elevation data sets, (3) repeat reclassifications
with different values to see how the different values affect which regions may be susceptible to
landslides, and (4) you can embed you model in other more complex models.

Open your project from Part I.

First create a new Toolbox by right-clicking on ArcToolbox and select New Toolbox and
name it “Landslide”. Note it will move to its alphabetically correct location in the Toolbox
order.

Create a new model within this Toolbox by right-clicking Landslide and selecting New
Model.
This will open the ModelBuilder window.

In Model use Model > Model Properties and check radio button to “store relative path
names”.

Name the model Landslide_Sus.

Click OK.

Right-click anywhere that is white in the ArcToolbox area.

Click on Environments and select General Settings and set Current Workspace to
C:\ArcProjects\Landslide92\

Set the Scratch Workspace to C:\ArcProjects\Landslide92\Scratch_Temp click OK
Copyright
© 2003-2005 Environmental Systems Research Institute, Inc.
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
Position the ArcMap window so that you can see the Table of Contents of ArcMap and
the Model window.

Click, drag, and drop the sb_dem grid onto the Model window. If this does not work, you
can use the Add Data button and ad it from the Grdfile folder.
You will now add “tools” from ArcToolbox by click, drag and dropping them on to the model.
First expand the Spatial Analyst Tools and Surface toolsets.

Click and drag each tool for Hillshade, Slope and Aspect tools onto the Model.

Use the connect tool
to draw an arrow between the input data set and each of the
functions (ovals for Slope, Aspect and Hillshade).
The input data sets are blue ovals. Functions are rectangles that turn yellow when connected
and have output determined. Output data sets are ovals that turn green when they are connected
to functions and have output determined. If they remain clear, you may need to click on the
output oval and set the output location and name of the dataset.

Right-click on each of the output ovals and select Rename and type in a name for each
that is appropriate (sb_slope, sb_aspect, sb_hillshade).

Click and drag the Sb_burn_serverity feature dataset onto the model.

Next, drag the Feature to Raster tool from the To Raster toolset onto the model from the
ArcToolbox.

Use the connect tool to connect the feature dataset to the Feature to Raster tool
function.

Right-click on the output oval and rename sb_burn_sev.

Double-click on the Feature to Raster function rectangle and Open.

For field choose VEGBURNSEV and enter 10 in Output cell size and click OK..

Click on the
tool to automatically arrange the model features (note you can zoom in
and out or change viewing area as needed.

If you want to see the output dataset of any of the functions in your ArcMap document,
right-click on the output oval and select Add to Display. At a minimum, you should
display the sb_hillshade.

Run the model (Model > Run).
Note: The ovals and rectangles will become “shaded” as the model runs. The “process”
functions turn red as the model is run. The model process window will let you know what
is happening in the model and if there are errors. Note: if you Run this or have created
the same data, you must remember to allow datasets to be overwritten.
Copyright
© 2003-2005 Environmental Systems Research Institute, Inc.
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
Once the processes have all been executed, you must close the dialogue box in order to
access the model or other documents. You can check the radio button on this dialog
window so that it will automatically close if the analysis was successful.
Now you will Reclass the sb_slope and sb_aspect using the Reclassify tool in the Reclass
Toolset in the Spatial Analyst toolbox.

Drag and drop the Reclassify tool from the Toolbox onto the model twice (once for
slope and once for aspect).

Use the connect tool to connect each to the sb_slope2 and sb_aspect2 output.

Right-click on each output oval and rename appropriately. Before running you will need
to set the reclassified values as you did earlier.

Double-click on the rectangle for reclassifying the slope dataset.

When dialogue opens, click on Precision button and set it to 0 decimal places then click OK.

Click on Classify button and pick Natural Breaks and type in 6 classes.

In the Break Values table (on right), highlight each value and change the values to 5, 10, 15, 25,
33, 81 and click OK.

In the New Values field, type in the values (click enter after each entry) in the Reclassify window
for each listed below:
0–5
5 – 10
10 – 15
15 – 25
25 – 33
33 – 81
0
0
1
3
6
6

Scroll down and for the Output raster browse to C:\ArcProjects\Landslide92\ Scratch_Temp
and name it Reclass_slp2.

Click Save and OK.
Now we will reclassify Aspect using the same tools used for Slope.

First double-click on the function rectangle for reclassifying aspect.

When dialogue opens, click on Precision button and set to 0 decimal places then click OK.

Click on Classify button and for Method pick Defined Interval and type in 30 for the Interval
Size value then click OK.

You will now set “New Values” in the Reclassify dialog box so that Aspect values from 0 to 90 and
170 to 360 (generally northward) will have a value of 0. Values from 90 to 120 and 240 to 270
will have a value of 1 and values from 120 to 240 will have a value of 2.
-1 to 0
0 to 30
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0
© 2003-2005 Environmental Systems Research Institute, Inc.
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30 to 60
60 to 90
90 to 120
120 to 150
150 to 180
180 to 210
210 to 240
240 to 270
270 to 300
300 to 330
330 to 360
0
0
1
3
6
6
3
1
0
0
0

Scroll down and for Output raster browse to C:\ArcProjects\Landslide92\
Scratch_Temp and name Reclass_aspt2.

Run the model again (Model > Run).
The output of these analyses will be used as the input for a Weighted Overlay that will include
reclassified values for slope, aspect and burn severity. It will be weighted so that slope values
are 60%, aspect and burn severity are 20% each of the output.

Click and drag the Weighted Overlay tool from the Overlay toolset from the Spatial
Analysis Toolbox on to the model.

Use the connect tool to connect to the reclassified slope, aspect and burn severity output
data set ovals.

Double-click on the rectangle for Weighted Overlay function.

In the % Influence column enter 20 for reclass_asp2 and sb_burn_sev and 60 for
Reclass_slp2. These values must add to 100 then click OK. .

Right-click on the Weighted_output oval and select Add to Display, Right click on it
again and rename Highest_Sus.

Run the Model (Model > Run).
You now want to find only those places that are greater the 4.5 in value. You will use the Spatial
Analyst Tools, Extract toolset, Extract by Attributes tool (this is a slightly different tool then we
used above in the previous part of this lesson).

Drag and drop the Extract by Attributes tool on the Model. Use the connect tool to
connect to the Input data.

Double-click on the function rectangle to open it.

For the input select the output of the Weighted overlay.

For the Where clause click on the SQL tool and double click on Value then type in > 4.8
(Value > 4.8) and click OK, then OK again.

Right-click on the output of the Extract by Attributes tool and select Add to Display.

Run the Model again.
Copyright
© 2003-2005 Environmental Systems Research Institute, Inc.
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Now you can reorder the data layers in the Table of Contents so that you can see the output of
the Model. You may want to rename some of the layers so that they are more descriptive or
change their Symbology or color.
How does the ModelBuilder results compare with the manual analysis you carried out?
Hint: Turn off all layers except the two grid data sets and compare them.

Save your project. If time permits you may want to go back and change the values or
percent influence and see how it changes your out.

After saving, close ArcMap.
Using the 3D Analyst Extension and ArcScene (you could also use
ArcGlobe) to visually display your data
You will now use the data from the output of your model to extrude and view your data in 3D.
You can use ArcGlobe or ArcScene – for this exercise we will use ArcScene. The elevation for
the surface of your 3D scene will be acquired from the elevation data layer (sb_dem). You will
drape other data on or slightly above (10 to 20 m) that surface. By using appropriate elevation
colorization (symbology and shading), you can view your data and “fly through” the area to
observe where landslide susceptibility is greatest. You can also add the burn severity layer to
visualize how extensive the fire was in the region.

Open ArcScene (Start > Programs > ArcGIS > ArcScene).

Ensure that the 3d Analyst extension is turned on (Tools > Extensions > 3D Analyst).

Turn on the 3D Analyst and Animation toolbars (View >
Toolbars> Animation).

Use the Add data button and add data (remember that grids and vector data are stored in
different folders so you will have to use the Add data button more then once) for roads,
faults, streams, geology, historic landslides, burn severity, elevation layer, or other
datasets you may want to display in your project.
If you do not remember where these datasets are saved, use ArcCatalog to view your
datasets (Preview tab) and the paths to your dataset including Sb_roads, Sb_faults,
Sb_streams, Sb_roads, Sb_Lndslds, sb_dem, sb_drg_clp and the Highest Sus dataset
that your created in your previous analysis. If you are prompted to create pyramids, click
Yes.

Right click on the sb_dem dataset and select Properties.

Click on Base Height tab and click on radio button “Obtain Heights for layer from
surface”.

Click the Browse button and select the sb_dem dataset.

Click on Raster Resolution below this dataset and be sure that it is set for 10 for X and
Y cell values (same as the original resolution) and click Apply.
Copyright
© 2003-2005 Environmental Systems Research Institute, Inc.
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
Next click on the Symbology tab and choose an appropriate color ramp for Elevations
then click Apply.
Tip: Right-click on the down arrow, uncheck Graphic, then type and “e” in the box – this
should bring in Elevation #1 ramp.

Next select the Rendering tab and under Effects check the radio button for “Shade
aerial features relative to the scene’s light position”.

Click OK. Add the other Grid datasets (remembering to set Raster Resolution and
Effects) using the same sequence of steps for each raster dataset.

Right-click on Sb_roads and pick Properties.

Click on Base Height tab and click on radio button “Obtain Heights for layer from
surface”.

Click the Browse button to select sb_dem dataset.

In the Offset dialogue box type 10. (You may need to adjust this value later as you add
data so that the features above the surface are seen above the surface).

Click Apply.

You may now want to pick a better color using the Symbology tab then click OK.

Repeat the above for each vector data set until all data layers are correctly placed and
symbolized in ArcScene
You can practice changing the angle of the Scene using the Navigation Tool
right, left and both mouse button.
and clicking
It is often necessary to exaggerate the terrain to better visualize you data.

Right-click on Scene Layer in the table of contents and click Scene Properties.

Click the General tab and type 2 in the Vertical Exaggeration box.

Click Apply.

Under Background Color, pick a different background color (light blue) for your scene.

Click OK.
You will now build a simple Animation fly through for your ArcScene project.

Zoom to full extent of your scene.

Click on the Capture View button

Zoom in to another location using the Navigation tool in your view and again click on the
Capture View button.
Copyright
.
© 2003-2005 Environmental Systems Research Institute, Inc.
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
Move to another new location (use Navigation tool and mouse buttons) and again click on
the Capture View button.

Repeat this process to add different views of you scene (zooming in, out or changing
angle of your view) and each time Clicking on the Capture View.

Click on the Open Animation Controls button
Animation Controls dialog.

Change Duration to 25.0 seconds.

Change Play mode to Loop forward.

Click on the “play arrow” and watch your animation.
and click on Options to open the
You can change the duration, Play Mode, Save or clear your animation (Click on Animation down
arrow and click on Save or Clear animation.) You can also save this as an .avi to share with
others. See the documentation that comes with 3D Analyst for other options available to create
more complex animations.
Copyright
© 2003-2005 Environmental Systems Research Institute, Inc.
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