Lab 06- Working with DEMs

Table of Content

  • Background
    • Description
    • Results
  • Summary
  • Reference

Background

This lab is aimed at learning how to use, manipulate and compare DEMs. I have been asked to construct a Digital Elevation Model (DEM) of the Big Cottonwood Canyon Watershed located off Wasatch Front in Utah. The map below illustrate the watershed of interest.

Click here for larger view

Description

I obtained the datasets of 2 m Lidar DEM, 5 m Auto-correlated DEM, 10 m NED DEM and 30 m NED DEM from USGS GIS portal. Click here for detailed method used in creating the DEMs for comparison.

Results

Find below the two maps created; one for DEM comparison and the other for proper view of the elevation peaks using contour

The map produced using different resolution showed a clear difference in the quality of image produced by each DEMs. It is obvious that the 2 m and 10 m DEMs gave images that are close to real life image. They will be useful for producing maps with more topography detail. The 5 m DEM look good too but not as the 2 m and 10 m, the image produced look rough. On the other hand, the image produced by th 30 m DEM looks blurry, this is due to more area being displayed within each pixel. I will recommend 2 m and 10 m DEM for the project because of the image quality. Click here for pdf of image comparing the DEMs

The 10 m and 2 m contour seems to be on point. The 30 m DEM show a clear evidence of deviation from the elevation peak points. Both the 10 m and 30 m DEMs have obvious pixel. However, the area captured within each pixel value differ; with the 30 m having more that is why there is a large digression of the elevation peak. The 5 m DEM also deviate a little. Click here for pdf of image of elevation peaks.

Elevation at Point XY.docx

The elevation points taken for each DEM are in the table here.

Summary

The choice of DEM for a project depends on the product desired, budget, time, and data storage.

Reference

Joe Wheaton 2016, Lab 06 - Working with DEMs. http://gis.joewheaton.org/assignments/labs/lab06-1/task-1. Retrieved on 28th February, 2017.

Utah GIS Portal, https://gis.utah.gov/data/#. DEMs. Retrieved on 28th February, 2017.