Gutierrez_E_Lab2

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:


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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.

Documents

Gutierrez_E_Lab2