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<br />(c) Assumption B, inflow design flood, thunderstorm rainfall <br /> <br />(1) The reduced rainfall amounts step (1) Assumption A, <br />above are the thunderstorm rainfall values used for <br />computing a flood for Assumption B. <br /> <br />(2) Obtain thunderstorm runoff curve number, CN from <br />Table A-9, Appendix A, Page 544 <br /> <br />Cover type: Brush, sage, grass or combinations, cover <br />density at ground surface - 50% or Iess, Zone III, Assumption <br />B thunderstorm. CN is 94 so from Table 5, Page 67 no <br />adjustment to T is necessary. <br />c <br /> <br />(3) Direct runoff increments for computing maximum <br />probable flood, Assumption B (values in inches) <br /> <br />., , IncrementaI Accum. <br />:; .; <br />,'! Time Reduced Reduced Direct Runoff <br /> Ending, Design Design I Accum. 1 Inc;~~.1 Incremental <br /> Hr. Rai nfaIl Rainfall Loss <br /> 0 0 0 () 0 0 <br /> 0.25 0.22 0.22 0.03 0.03 O. 19 <br /> 0.50 0.32 0.54 0.18 0.15 O. 17 <br /> 0.75 0.43 0.97 0.55 0.37 0.05 <br /> 1.00 0.89 1.86 1.30 0.75 0.142 <br /> 1.25 0.19 2.05 1.48 0.13 0.06 <br /> 1.50 0.13 2.18 1.60 0.07 0.06 <br /> 1.75 0.09 2.27 1.70 0.03 0.06 <br /> 2.00 0.07 2.34 1. 78 0.01 0.06 <br /> 2.25 0.06 2.40 1. 84 0.00 0.06 <br /> 2.50 0.05 2.45 1.88 0.00 0.05 <br /> .2.75 0.02 2.47 1.90 0.00 0.0.2 <br /> 3.00 0.02 2.49 1.91 0.00 0.02 <br /> 1 Using CN = 94, AMC II, Figure A-4, Appendix A, Page 541 <br /> 2 Computation by CN 94 gives 0.01 inch per IS-minutes. Abandon curve and <br /> use 0.06 inch per IS-minutes for IS-minute sto~'11 increments. <br /> <br />- 17 - <br />