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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

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Agricultural Practices Livestock Grazing Tillage Hillside Farming Drain Tile

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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

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Questions??