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<br />RUNOFF CGtlPUTATIONS <br /> <br />The SCS Method. as described in National Engineering Handbook, <br />Chapter 16 (Ref. 2). was selectE,d as the method which would best <br />represent the runoff characteristics of the Spring Creek Tribu- <br />tary basin. Weighted average cur-ve numbers were computed using <br />soil and land use maps. The tin~ of concentration was determined <br />using stream hydraulics of apprQ~imate cross-sec~ions taken from <br />U.S.G.S. 7.5 minute topographic maps. These computations are sum- <br />marized in three SCS hydrologic work sheets (See Appendix). Dis- <br />charges were computed for the 10- and 100-year flood events and <br />plotted on log-probability paper (See Appendix, Figure 2). The <br />50- and SOO-year discharges were obtained by straightline extra- <br />polation of the 10- and 100-year values. <br /> <br />The discharges recommended for woe in the Town of Nunn Flood In- <br />730 1400 /780 ?8so <br />surance Study are ,).IX! cfs, ~ (jfs, ~ro cfs, and ~ cfs for <br />the 10-, SO-, 100- and SOD-year floods respectively. <br /> <br />'* <br /> <br />preparc/cl by: <br /> <br />.G ~ <br />-' ~/eA{e/ /~, i .', <br />~---=::--~~~_D <br />Gene A. Klllan, E.I.T. <br /> <br />Reviewed by: <br />'I <br />,1\Z ,I / /' -# .df1 <br />___" _~C!r:~(' Cij LJ.-:::tCh / <br />DouirraE' C. .otovall,. F.'. <br /> <br />REVISE/> A(O <br />Grlt:i <br /> <br />1/27/78 <br /> <br />-,1- <br />