Topographic Changes in River Feshie
Change Detections
In order to determine the changes in topography between 2003-2004 and 2004-2005 I used the Geomorphic Change Detection software in ArcMap. This calculated the elevation differences between both sets of years and shows raising and lowering of elevation with 80% confidence.
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Budget Segregation
After using GCD to determine the topographic change, this was then used to classify certain geomorphic features as either erosional or depositional. Areas near the edge of the channel with strong elevation lowering were classified as Bank Erosion. Mid-channel areas with moderate elevation lowering were classified as Degradation. Mid-channel areas with moderate elevation raising were classified as Aggradation. Areas with strong elevation raising, either mid-channel or along the banks, were classified as Bar Development.
Bank Erosion
Total Volume of Surface Lowering (m³): 287 ± 100
Total Area of Surface Lowering (m²): 443
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Bank Erosion occurs when there is a large amount of elevation change in a relatively small area. This can be seen below because there is significant lowering in the channel over a relatively small area. This can be seen in that bank erosion makes up the high magnitude change values on the graphs, and that the total affected area is relatively small.
Degradation
Total Volume of Surface Lowering (m³): 133 ± 43
Total Area of Surface Lowering (m²): 282
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Degradation is considered a diffuse event because it causes a relatively small lowering in elevation over larger areas of the channel.
Bar Development
Total Volume of Surface Raising (m³): 227 ± 70
Total Area of Surface Lowering (m²): 850
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Bar development can be either a concentrated or a diffuse event depending on the channel form. This is seen below with the wider distribution of elevation raising.
Aggradation
Total Volume of Surface Raising (m³): 165 ± 57
Total Area of Surface Lowering (m²): 813
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Aggradation is considered a diffuse event because is causes a small elevation raising over larger areas of the channel. This can be seen numerically because the total volume of surface raising is relatively small compared to the total area of surface raising.
