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<br />APPENDIX C -- SUMMARY OF EQUATIONS FOR
<br />ESTIMATING BASIN LAGTIME
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<br />[LT, basin lagtime, in hours] OHIO
<br /> Small rural LT=16,4S.,78 (F+IO).38 35
<br /> Standard (ST+I),31
<br />SlatelAreaIRegion Equation Error In LT=1.07L.14 S.,27 (13-
<br /> percent Small urban 48
<br /> BDF).42
<br />ALABAMA ARKANSAS
<br />North of fall line LT=2,66A46 S,.08 32 Rural LT=256A.90(p-30),61
<br /> LT=5,06Aso S,.20 33
<br />South of fall line 31 QIOO.,6SQp',16 S'.2.1
<br />Statewide, urban LT=2.85A29S S..I83 21 Memphis urban LT=2,05A3S C-,87IA.,22 24
<br /> 1A','22 MISSOURI RURAL
<br />TENNESSEE Equation I LT=2,79L,39 S..I9S 26
<br />East LT=1.26L.82.1 47 LT=I.46A.27
<br /> LT=O,94L86 Equation 2 26
<br />Central 39 MISSOURI URBAN
<br />Central, urban LT=1.64L,491A'.I6 16 LT=O,87L,60 S,,30 (13.
<br /> LT=O,707A13 Equation 1 23
<br />West 43 BDF)o,4S
<br />West. urban LT=2,65A348IA.,3S7 39 Equation 2 LT=O,32Aso (l3-BDF)37 22
<br />GEORGIA OKLAHOMA LT=O.206A239 S.,280 40
<br />North of fall line LT=4,64A49 S.,21 31 R1242,14
<br />South of fall line LT=13,6A.43 S.,31 25 NATIONWIDE URBAN
<br />Atlanta urban LT=16IA22 S.,66IA.,67 19 Equation 1 LT=O.85L,62 S,,31 (13. 76
<br />SOUTH CAROLINA BDF)o.47
<br />(average basin Ll) Equation 2 LT=,OO30L7'(l3- 61
<br />Blue Ridge LT=3,71A26S 7 BDF),34(ST + 10)2.53
<br />Piedmont LT=2,66A460 26 RI2.,44IA',20S.,14
<br />Inner Coastal PI. LT=6,IOA417 34 A = drainage area, in square miles
<br />Lower Coastal PI. S = main channel slope, in fpm
<br />Region 1 LT=6,62A341 26 L = main channel length, in miles
<br />Region 2 LT=IO,88A341 26 Qp = peak discharge, in cfs
<br />SOUTH CAROLINA F = percent forest area
<br />(Qp adj, Ll) ST = percent of surface storage in basin
<br />Blue Ridge LT=7,21A322 Qp,.I'2 P = mean annual precipitation. in inches
<br />Piedmont LT=3.30A614 Qp,.120 QIOO = 1000year recurrence interval peak discharge, in cfs
<br />Inner Coastal PI. LT=7,03A37S Qp"OIO IA = percent of basin co~red by impervious surfaces
<br /> BDF = basin development factor
<br />Lower Coastal PI. RI2 = 2-year 2-bour rainfall intensity
<br />Region I LT=6.95A348 Qp,,022 R124 = 2-year 24-bour rainfall
<br />Region 2 LT=11.7 A348 Qp,,022 C = channel condition (unpaved I, full paved 2)
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<br />196 Nationwide Summary 01 U.S. Geological Survey Reglo..1 Regression Equation. lor E.t1matlng Magnitude and Frequency 01
<br />Floods for Ung8ged Sit.., 1993
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