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.; <br />Sediment Delivery Ratio <br />Although the sediment delivery ratio is not part of the original <br />Universal Soil Loss Equation, its addition here is considered <br />important because the configuration of the reclamation sites does <br />permit some deposition of sediment before reaching the sediment <br />ponds at the low point of each site. A number of methods can be <br />used such as the area-delivery ratio and the relief-length ratio. <br />The U.S. Forest Service developed a method in 1980 which takes <br />into account percent ground cover, convex or concave shapes of <br />the watershed, slope gradient, delivery distance, surface <br />roughness of the soil, surface runoff factor and texture of the <br />eroded material. This method uses a stiff diagram to calculate an <br />area which is then divided by the total area of the diagram to <br />develop a delivery ratio. The method is explained in "Applied <br />Hydrology and Sedimentology for Disturbed Areas" by Barfield, <br />Warner and Haan. Unfortunately, many of the factors it considers <br />have already been considered in the main Universal Soil Loss <br />Equation. <br />The relief-length ratio calculates a reduction factor for <br />• sediment delivered based upon the degree that the watershed in <br />question is channelized. A poorly-channelized watershed will <br />transport the sediment slowly and provide places for sediment <br />deposition. This method is based on data gathered for a watershed <br />in flat areas of the Red Hills of Oklahoma and Texas. It is not <br />applicable to steep areas in Colorado. <br />The area-relief ratio calculates <br />delivered depending upon the size <br />area-delivery ratio for all sites <br />sediment delivery ratios for the <br />follows: <br />Northern #1 Area = 11.74 acres = <br />• <br />a reduction factor for sediment <br />of the drainage area. Using the <br />and the chart shown below, the <br />sites would be as described as <br />0183 sq. miles = 60A; del. ratio <br />Refuse Area = 10.6 acres = .0165 sq. miles = 64~ del. ratio <br />Rienau #2 Area = 5.0 acres = .0078 sq. miles = 70~ del. ratio <br />Since the sediment delivery ratio estimation is far from an exact <br />/V(- l2 kF <br />7~.zD~93 <br />