Laserfiche WebLink
<br />CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD ] <br /> <br />Project Title: <br />Catchment ID: <br /> <br />Kiowa Approximate Zone A Study <br /> <br />I. Catchment Hydrologic Data <br /> <br />Catchment ID = South <br />Area = 1293.00 Acres <br />Percent Imperviousness = 2.00 % <br />NRCS Soil Type = B A, B, C, or D <br />For catchments larger than 90 acres, CUHP hydrograph and routing are recommended. <br /> <br />II. Rainfall Information I (inch/hr) = C1 . P1/(C2 + Td)^C3 <br /> <br />Design Storm Return Period, Tr = <br />C1 = <br />C2= <br />C3= <br />P1= <br /> <br />100 years <br />28.50 <br />10.00 <br />0.786 <br />4.20 inches <br /> <br />(input return period for design storm) <br />(input the value of C1) <br />(input the value of C2) <br />(input the value of C3) <br />(input one-hr precipitation--see Sheet "Design Info") <br /> <br />III. Analysis of Flow Time (Time of Concentration) for a Catchment <br /> <br />Runoff Coefficient, C = <br />Overide Runoff Coefficient, C = <br />5-yr. Runoff Coefficient, C-5 = <br />Overide 5-yr. Runoff Coefficient, C = <br /> <br />0.36 <br />(enter an overide C value if desired, or leave blank to accept calculated C.) <br />0.08 <br /> <br />(enter an overide C-5 value if desired, or leave blank to accept calculated C-5_) <br /> <br />Illustration <br /> <br /> <br />FloIv Dinctio <br />( <br /> <br />C...tdunent <br />Boundary <br /> <br />NRCS Land Heavy Tillage! Short Nearly Grassed Paved Areas & <br />Type Meadow Field Pasture! Bare Swales! Shallow Paved Swales <br /> Lawns Grou nd Waterways (Sheet Flow) <br />Conveyance I 2_5 I 5 7 ~~___J1 15 I 20 <br /> <br />Calculations: <br /> <br />Reach Slope Length 5-yr NRCS Flow Flow <br />ID S L Runoff Convey- Velocity Time <br /> Coeff ance V Tf <br /> ftfft ft C-5 fps minutes <br /> input input output input output output <br />Overland 0.0600 500 0.08 N/A 0.37 22.76 <br />1 0.0220 16,607 5.00 0.74 373.22 <br />2 <br />3 <br />4 <br />5 <br /> Sum 17,107 Computed Tc -- 395.98 <br /> Regional Tc = 105.04 <br /> User-Entered Tc = 105.04 <br /> <br />IV. Peak Runoff Prediction <br />Rainfall Intensity at Computed Tc, I = <br />Rainfall Intensity at Regional Tc, I = <br />Rainfall Intensity at User-Defined Tc, I = <br /> <br />1.07 inch/hr <br />2.87 inchlhr <br />2.87 inch/hr <br /> <br />Peak Flowrate, Qp = <br />Peak Flowrate, Qp = <br />Peak Flowrate, Qp = <br /> <br />499.37 cfs <br />1345.48 cfs <br />1345.48 cfs <br />--- <br /> <br />UD-RationaISouthBasin.xls, Tc and PeakQ <br /> <br />1/23/2006, 3:45 PM <br />