Jens Ammon
Open Source GIS Alternatives
This exercise showcases that data mapping and geographic analysis can be done effectively without an ESRI GIS license. There are multiple public access data sources and open source analysis programs that produce similar, if not better, results than GIS.
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Free LiDAR point data obtained from OpenTopography, a growing public LiDAR database that covers much of the United States and select parts of the world. The point data was then converted to a DEM through CloudCompare, and the DEM was then processed in QGIS to make a variety of terrain analysis such as hillshades, slope maps and aspect maps.
Alluvial Fan
Death Valley, CA
Death Valley National Park was the first LiDAR dataset obtained from OpenTopography. The alluvial fans spreading into the valley are good representations of a low-relief landform, and the multiple small channels within the fan are modeled well with the fine resolution of LiDAR data.
In this example, the point cloud LiDAR data was converted into a Digital Elevation Model. The DEM was then used to create a hillshade for the region. Contour lines with an interval of 20 m were then overlaid on top to accentuate the concentric and symmetrical shape of the alluvial fan.
Temple Creek Tributary
Logan, UT
The second LiDAR dataset analyzed was the section of the Utah Bear River Mountain Range containing the Temple Creek tributary in the Logan River Watershed. This dataset was chosen as a high-relief study area so slope analysis tools would be more meaningful. A similar landscape would also be present at the headwaters of the river that made the above alluvial fan.
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In this example, point cloud LiDAR data was converted into a Digital Elevation Model. The DEM was then used to create both a hillshade and a slope steepness layer for the region. The slope model gives a portrayal of how precipitation and runoff flows over the landscape into the main tributary channels.