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graphs representing Curve numbers 78 and 72 data for example, there is a large change <br />in the number of check dams needed even though the two situations could be as short <br />as about two years in time. <br />Similarly, Figures 7a, 7b, 7c, and 7d provide this same data in a slightly different format. <br />In this case, the total acre feet of storage is shown rather than the number of check dams. <br />Part 3 <br />Sediment Contribution and Controlling Runoff on Recent Reclamation <br />The preceding portion of this guideline deals with mature or relatively mature reclaimed <br />areas which are approaching bond release. For recently topsoiled and seeded areas and <br />less mature reclaimed areas, it is important to control the runoff volume near the source. <br />Additionally, the earlier discussion only deals with the hydrologic design with no <br />consideration given for estimation of the amount of sediment deposition which may occur, <br />particularly during the early phases of reclamation. <br />The SEDCAD model is specifically designed to predict sediment yield under a variety of <br />conditions. <br />Appendix H provides a series of SEDCAD models with sedimentology included. Again, <br />a generic 640 acre watershed under the 10 year 24 hour storm event has been modeled <br />under a variety of reclamation conditions. Modeling of this watershed has been provided <br />for the following cases for a watershed slope of both 10% and 15% slopes for these curve <br />numbers: <br />• Curve number 86 (representative of recently topsoiled areas), <br />• Curve number 83 (representative of a 50%/50% mixture of recently topsoiled areas <br />and one year reclamation), <br />• Curve number 80 (representative of 1 year reclamation) <br />• Curve number 78, <br />• Curve number 76, <br />• Curve number 72, <br />• Curve number 67 (representative of 2 year reclamation), and <br />• Curve number 62 (mature, 4 plus year reclamation approaching bond release). <br />Table 2 provides a summary of the Appendix H results for these 16 separate SEDCAD <br />models. The final three columns provide the model output, with peak flow (Q) in cfs, total <br />runoff volume in acre-feet, and the tons of sediment delivered by the 10 year, 24 hour <br />design storm. <br />