This document describes procedures for analyzing terrain and solar insolation for different vegetation types in the Santa Monica Mountains using GIS tools. The key findings are that chaparral exists at the highest elevations and steepest slopes, receiving the lowest solar insolation, while urban agriculture exists at the lowest elevations and receives the highest insolation. Annual grass has a relatively high slope given its low mean elevation. The analysis finds patterns between vegetation types and terrain/solar factors as expected.

1. GEOG 170 Lab 2: DEM and Terrain Analysis Enrique Gutierrez
Professor Sheng Santa Monica Mountains Austin Madson
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2. GEOG 170 Lab 2: DEM and Terrain Analysis Enrique Gutierrez
Professor Sheng Santa Monica Mountains Austin Madson
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3. GEOG 170 Lab 2: DEM and Terrain Analysis Enrique Gutierrez
Professor Sheng Santa Monica Mountains Austin Madson
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4. GEOG 170 Lab 2: DEM and Terrain Analysis Enrique Gutierrez
Professor Sheng Santa Monica Mountains Austin Madson
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5. GEOG 170 Lab 2: DEM and Terrain Analysis Enrique Gutierrez
Professor Sheng Santa Monica Mountains Austin Madson
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6. GEOG 170 Lab 2: DEM and Terrain Analysis Enrique Gutierrez
Professor Sheng Santa Monica Mountains Austin Madson
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7. GEOG 170 Lab 2: DEM and Terrain Analysis Enrique Gutierrez
Professor Sheng Santa Monica Mountains Austin Madson
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8. GEOG 170 Lab 2: DEM and Terrain Analysis Enrique Gutierrez
Professor Sheng Santa Monica Mountains Austin Madson
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Procedures:
First, I downloaded the files from the class website. I then downloaded the DEM raster
data from the USGS website. Once I assembled all of the files into my folder, I imported the
raster tiles from USGS. I then projected each of them to UTM Zone 11N using the Project tool.
I then combined them using the Mosaic raster tool. After that, I projected the mosaicked raster.
Then, I imported the National Park Service (NPS) boundary layer. I projected the NPS layer to
UTM Zone 11N. I then used the select by rectangle option to select only the Santa Monica
Mountains. I then created a layer from the selected feature. After which, I created a shape file of
the layer. I then used the clip tool to clip the mosaic raster to the NPS boundary. Within that
dialog box, I checked the box named ‘use input features for clipping geometry (optional). I then
projected the clipped mosaic again to UTM Zone 11N. I exported the DEM map since that is
elevation. I used the slope and aspect tools respectively to create rasters for each of these. I then
calculated the solar angles for the four seasons. Then I created the hillshade rasters for each
season using the hillshade tool. From each hillshade raster, I imported each into the raster
calculator tool, and multiplied each by 1000 and divided each by 255 in order to create the solar
insolation rasters. I then imported the vegetation layer. I clipped the layer to the NPS boundary.
I then exported that layer as a shape file. I then projected that vegetation layer to UTM Zone 11.
I then used the zonal statistics table as tables to obtain data for each respective map. I then
exported all of the relevant maps to a word document. I also exported the relevant data to an
excel spreadsheet. I then moved the charts and graphs to the word document and formatted it.
After that, the final step prior to submission was to convert the word document into a pdf.
Analyzing Results:

9. GEOG 170 Lab 2: DEM and Terrain Analysis Enrique Gutierrez
Professor Sheng Santa Monica Mountains Austin Madson
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The vegetation with the lowest slope is Urban Agriculture. This is intuitive as urban
agriculture is usually tended to by people and people live in flatter urban areas. In the case of the
mountains, this vegetation type while not easily accessible to humans is relatively more
accessible than the other three types. On the other end of the spectrum, Chaparral is located on
steeper slopes indicating it is wilder and less liable to human interaction.
All vegetation types have a southern aspect. This too is intuitive. Being within the
northern hemisphere, plants will face south in attempt to capture sunlight in the most direct
fashion. The Sun’s most direct rays hit the equator and the tropics for most of the year. Since
both are south of the Santa Monica Mountains, the plants turn south for more direct sunlight.
The highest elevation by vegetation type is that of the chaparral, with an average of
450.71 meters. This makes sense, as it also has the highest slope. This shows that chaparral is
relatively less accessible to human contact. The lowest is Annual Grass with a mean elevation of
172.56 meters.
Summarizing Results:
As expected, summer has the highest solar insolation while winter has the lowest. Spring and
fall both have very similar levels of solar insolation. Annual Grass and Urban Agriculture had
the highest levels of solar insolation while Coastal Scrub had moderately less solar insolation.
Chaparral has considerably lower levels of solar insolation than all other vegetation types.
Interesting Findings:
One important thing to note is the considerably lower level of solar insolation received by
the chaparral. Another, is the relatively high slope of Annual grass given its mean elevation.