The Impact of Erosion from Water Runoff By: Nicolas Wieland and
Tony Nixon
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Overview Farm in Scott County, Minnesota Erosion occurs on a
cattle pasture Drain tile directs water flow Additional surface
water flow All water drains to a wetland
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Contributing Area
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Erosion Erosion - is the process by which soil and rock are
removed from the Earth's surface by natural processes such as wind
or water flow, and then transported and deposited in other
locations Most noticeable source of erosion: water runoff/drainage
Influencing factors to erosion: vegetation cover, topography, soil
structure, and quantity of water
Materials Total Station Prism Rod Global Positioning System
Geographic Information System Microsoft Excel Field Notebook
Pitchfork Knee Boots
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Methods: Data Collection Visual inspection of site Revealed
slight long-term erosion and very severe erosion Total Station for
collecting elevation information Recorded Horizontal Angle,
Horizontal Distance, Vertical Distance, and sufficient notes
Benchmark set as 100 feet 4 groups of foreshots: undisturbed
terrain, slightly eroded terrain, 2 sets to define the aggressive
erosion
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Four Groups of Foreshots
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Methods: ArcMap Analysis IDW interpolation of digital elevation
models (DEM) Predicted Actual Use break lines in interpolation for
increased accuracy Gully edge for actual elevation model Gully
centerline for predicted elevation model Predicted elevation model
excluded the points from the bottom of the gully Raster calculator
subtracting cell values of the DEMs Surface volume calculation
Contributing area determination and calculation
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From Tile Exit to Bottom 430 feet long 16.5 vertical feet 5
vertical feet from south edge to tile exit
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Results 8,659.7 cubic feet removed 2.9 cubic feet not removed
94 acres contributing to runoff
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Analysis IDW vs. Spline interpolation Dirt 'not' eroded
Non-erodable materials
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Implications 12 inches of snow + 0.5 inch of rain = 683,000
cubic feet (5.1 million gallons) Melt and drain in 5 days
Impermeable frost layer or saturated ground = 1.5 cubic feet per
second (average) Reasonably double, or more, at times
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Geeky Stuff 2 feet high column of water exerts 1 psi. Assume
water flows at 2 feet/second = 1.5+ feet cross section of water =
216+ square inches Pressure adds up quickly