Embedded Files
Topographic Points and Breaklines Screenshot
Topographic Points and Breaklines Screenshot
The raw data provided to develop a TIN (Triangular Irregular Network) interpolated surface and then a DEM (Digital Elevation Model). The data consists of a set of topographic points that were categorized into their corresponding banks (i.e. left of bank, right of bank, and others that allowed for the creation of the the breaklines shown). As the data is in this raw form, one can distinguish various features such as channels and banks.
The raw data provided to develop a TIN (Triangular Irregular Network) interpolated surface and then a DEM (Digital Elevation Model). The data consists of a set of topographic points that were categorized into their corresponding banks (i.e. left of bank, right of bank, and others that allowed for the creation of the the breaklines shown). As the data is in this raw form, one can distinguish various features such as channels and banks.
TIN (Triangulated Irregular Network)
TIN (Triangulated Irregular Network)
We used the raw data to create a TIN. We refined the TIN to remove dams at the top and bottom of the reach, and remove facets near banks. This allows for more accurate depictions of the banks without any over-interpolated points skewing the data. Beaver dams are fairly visible as the map is made more resolute. Breaklines can be defined a more of a boundary that separtes portions of the DEMs representing the stream area.
DEM Comparison
DEM Comparison
DEM_Comp.pdfIn the figure on the left is a representation of the 7 DEMs that were compared, all were compared at different resolutions to illustrate the quality of each. Each DEM was created using the TIN shown in the upper right hand side of the figure. The stream reach is that if the Pat's Cabin Area of the Bridge Creek Watershed. From the analysis, the 100m, the 25m, and the 20m resolutions are too pixelated to be used for any real analysis. The 15m, 10 m, and the 5m DEMs are prime for analysis because the .50cm resolution, for example, offers high quality surface feature resolution while not incurring large amounts of data storage like the other more precise analyses. Depending on the purpose of the project and potential analysis, it really depends on which resolution is best for your project. For the purpose of determining channel and bank analysis the .50cm was chosen to make this particular analysis.
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50cm DEM Stream Profile and Cross Sections
50cm DEM Stream Profile and Cross Sections
Watershed Reach.pdfThe figure to the left shows the water depth and the stream profiles for various points on the Pat's Cabin Reach portion of the watershed. The water depth was created by utilizing the raster calculator and subtracting the .50cm DEM from the surface water points layer. This allowed, with changes in the symbology, to view the water depth at the various extents of the reach. In the example I decided to use the .50cm DEM because of the high resolution of the pixels. There are 5 cross-sections that are displayed to show the elevation changes across the reach and a stream profile to illustrate the change in elevation over the course of the reach. This aspect allows the analyzer to better understand the geomorphic change occurring in the stream and shows how Beaver Dams can benefit a stream's biodiversity.
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