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4 <br />Soil Loss Estimation <br />All sections of shoreline marked either severe or very severe were divided into <br />sites for analysis. For every section of severe or very severe erosion the <br />following variables were calculated: <br />• Depth: horizontal distance from the toe to the top of the bank; <br />calculated using GIS <br />• Height: vertical height; measured with Nov. 2011 LiDAR <br />elevation data <br />• Slope Length: length of diagonal slope; calculated <br />from depth and height measurements <br />• Recession Rate: yearly lateral recession of bank <br />(.4 ft/yr for severe erosion and .75 ft/yr for very <br />severe erosion) <br />• Length: length of the erosion along the river; <br />calculated using GIS <br />Recession <br />Rate <br />Depth <br />These variables were used in the equation below to calculate the annual soil loss. Sandy soil <br />weighs approximately 100 pounds per cubic foot. <br />SlopeLength(ft) * Re cessionRate(ft / yr) * Length(ft) * 100(7/9 / ft3 ) <br />2000(/b / ton) <br />Estimated Soil <br />Loss (tons/year) <br />