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{"sheet":"Intro","index":0,"n_rows":45,"n_cols":8,"rows_kept":45,"cut":false,"hidden":false,"merged":[[1,1,3,7],[6,1,6,7],[5,1,5,7],[4,1,4,7]]}
[]
[null,"PEAK RUNOFF PREDICTION BY THE RATIONAL METHOD"]
[]
[]
[null,"Version 1.02a, Released August 2005"]
[null,"Urban Drainage and Flood Control District"]
[null,"Denver, Colorado"]
[]
[null,"Purpose:","This workbook applies the Rational Method to estimate stormwater"]
[null,null,"runoff and peak flows from small urban catchments,"]
[null,null," i.e., typically less than 90 acres."]
[]
[null,"Function:","1.  To apply the area-weighting method to calculate the representative"]
[null,null,"      runoff coefficient C for a catchment."]
[]
[null,null,"2.  To calculate the time of concentration, and then compare with "]
[null,null,"      the empirical time of concentration limit used for the Denver region.  "]
[null,null,"      The smaller one is recommended as the rainfall duration for "]
[null,null,"      use with the Rational Method."]
[]
[null,null,"3.  To calculate the design rainfall intensity and peak flow rate."]
[]
[null,"Content:","The workbook consists of the following five sheets:"]
[]
[null,"Intro","Describes the purpose of each sheet in the workbook."]
[]
[null,"Weighted C","Applies the area-weighting method to determine the runoff C."]
[]
[null,"Tc and PeakQ","Calculates Tc and Q-peak."]
[]
[null,"Design Info","Provides the recommended runoff C's for various land uses."]
[]
[null,"Notation","Defines the variables used. "]
[]
[null,"Acknowledgements:","Spreadsheet Development Team:"]
[null,null,"Dr. James C.Y. Guo, P.E."]
[null,null,"Professor, Department of Civil Engineering"]
[null,null,"University of Colorado at Denver"]
[null,null,"Ken A. MacKenzie, P.E."]
[null,null,"Urban Drainage and Flood Control District"]
[null,null,"Wright Water Engineers, Inc."]
[null,null,"Denver, Colorado"]
[null,null," "]
[null,"Comments?","Direct all comments regarding this spreadsheet workbook to:",null,null,null,null,"UDFCD E-Mail"]
[null,"Revisions?","Check for revised versions of this or any other workbook at:",null,null,null,null,"Downloads"]

{"sheet":"Weighted C","index":1,"n_rows":38,"n_cols":7,"rows_kept":38,"cut":false,"hidden":false,"merged":[[1,1,1,8],[4,2,4,8],[5,2,5,8]]}
[]
[null,"Area-Weighting for Runoff Coefficient Calculation"]
[]
[]
[null,"Project Title:"]
[null,"Catchment  ID:"]
[]
[null,"Illustration "]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[null,"Instructions:  For each catchment subarea, enter values for A and C."]
[]
[null,null,null,"Subarea","Area","Runoff","Product"]
[null,null,null,"ID","acres","Coeff."]
[null,null,null,null,"A"," C*","CA"]
[null,null,null,"input","input","input","output"]
[null,null,null,null,null,null,{"$f":"IF(F25=\"\",\"\",(F25*E25))","v":""}]
[null,null,null,null,null,null,""]
[null,null,null,null,null,null,""]
[null,null,null,null,null,null,""]
[null,null,null,null,null,null,""]
[null,null,null,null,null,null,""]
[null,null,null,null,null,null,""]
[null,null,null,null,null,null,""]
[null,null,null,null,null,null,""]
[null,null,null,null,null,null,""]
[null,null,null,"Sum:",{"$f":"SUM(E25:E34)","v":0},"Sum:",{"$f":"SUM(G25:G34)","v":0}]
[]
[null,null,null,null,null,"Area-Weighted Runoff Coefficient (sum CA/sum A) =",{"$f":"IF(E35=0,\"\",G35/E35)","v":""}]
[null,"*See sheet \"Design Info\" for inperviousness-based runoff coefficient values."]

{"sheet":"Tc and PeakQ","index":2,"n_rows":103,"n_cols":53,"rows_kept":103,"cut":false,"hidden":false,"merged":[[41,7,41,8],[42,7,42,8],[40,7,40,8],[55,2,55,3],[1,1,1,8],[4,2,4,8],[5,2,5,8],[39,7,39,8]]}
[]
[null,"CALCULATION OF A PEAK RUNOFF USING RATIONAL METHOD"]
[]
[]
[null,"Project Title:"]
[null,"Catchment ID:"]
[]
["I.","Catchment Hydrologic Data"]
[]
[null,"Catchment ID ="]
[null,"Area =",null,"Acres"]
[null,"Percent Imperviousness =",null,"%"]
[null,"NRCS Soil Type =",null,"A, B, C, or D"]
[null,{"$f":"IF($BA$102=\"\",\"\",$BA$102)","v":""}]
[]
["II.","Rainfall Information   I (inch/hr) = C1 * P1 /(C2 + Td)^C3"]
[]
[null,"Design Storm Return Period, Tr =",null,"years","(input return period for design storm)"]
[null,"C1 =",null,null,"(input the value of C1)"]
[null,"C2=",null,null,"(input the value of C2)"]
[null,"C3=",null,null,"(input the value of C3)"]
[null,"P1=",null,"inches","(input one-hr precipitation--see Sheet \"Design Info\")"]
[null," "]
["III.","Analysis of Flow Time (Time of Concentration) for a Catchment"]
[]
[null,"Runoff Coefficient, C =",{"$f":"IF($BA$100=\"\",\"\",$BA$100)","v":""}]
[null,"Overide Runoff Coefficient, C =",null,"(enter an overide C value if desired, or leave blank to accept calculated C.)"]
[null,"5-yr. Runoff Coefficient, C-5 =",{"$f":"IF($BA$101=\"\",\"\",$BA$101)","v":""}]
[null,"Overide 5-yr. Runoff Coefficient, C =",null,"(enter an overide C-5 value if desired, or leave blank to accept calculated C-5.)"]
[null,null,null,null,"Illustration"]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[null,"NRCS Land","Heavy","Tillage/","Short","Nearly","Grassed","Paved Areas &"]
[null,"Type","Meadow","Field","Pasture/","Bare","Swales/","Shallow Paved Swales"]
[null,null,null,null,"Lawns","Ground","Waterways","(Sheet Flow)"]
[null,"Conveyance",2.5,5,7,10,15,20]
[null," "]
[null,"Calculations:","Reach","Slope","Length","5-yr ","NRCS","Flow","Flow"]
[null,null,"ID","S ","L ","Runoff","Convey-","Velocity","Time"]
[null,null,null,null,null,"Coeff","ance","V ","Tf "]
[null,null,null,"ft/ft","ft","C-5"," ","fps","minutes"]
[null,null," ","input","input","output","input","output","output"]
[null,null,"Overland",null,null,{"$f":"IF(C29=\"\",IF(C28=\"\",\"\",C28),C29)","v":""},"N/A",{"$f":"IF(I50>0, +E50/(60*I50),0)","v":0},{"$f":"IF(E50>0, 0.395*(1.1-F50)*E50^0.5/D50^0.33, 0)","v":0}]
[null,null,1,null,null," ",null,{"$f":"IF(E51=\"\",\"\",(G51*D51^0.5))","v":""},{"$f":"IF(H51=\"\",\"\",(E51/(60*H51)))","v":""}]
[null,null,2,null,null," ",null,{"$f":"IF(E52=\"\",\"\",(G52*D52^0.5))","v":""},{"$f":"IF(H52=\"\",\"\",(E52/(60*H52)))","v":""}]
[null,null,3,null,null," ",null,{"$f":"IF(E53=\"\",\"\",(G53*D53^0.5))","v":""},{"$f":"IF(H53=\"\",\"\",(E53/(60*H53)))","v":""}]
[null,null,4,null,null," ",null,{"$f":"IF(E54=\"\",\"\",(G54*D54^0.5))","v":""},{"$f":"IF(H54=\"\",\"\",(E54/(60*H54)))","v":""}]
[null,null,5,null,null," ",null,{"$f":"IF(E55=\"\",\"\",(G55*D55^0.5))","v":""},{"$f":"IF(H55=\"\",\"\",(E55/(60*H55)))","v":""}]
[null,null,"Sum",null,{"$f":"SUM(E50:E55)","v":0}," ",null,"Computed Tc =",{"$f":"ROUND(SUM(I50:I55),2)","v":0}]
[null,null,null,null," ",null,null,"Regional Tc =",{"$f":"ROUND(+$E$56/180+10,2)","v":10}]
[null,null,null,null,null,null,null,"User-Entered Tc ="]
[]
["IV.","Peak Runoff Prediction"]
[null,null,"Rainfall Intensity at Computed Tc, I =",{"$f":"IF(I56=0,\"\",($C$19*$C$22/($I$56+$C$20)^$C$21))","v":""},"inch/hr",null,null,"Peak Flowrate, Qp =",{"$f":"IF($C$27=\"\",IF($C$26=\"\",\"\",IF($D$61=\"\",\"\",$C$26*$C$11*$D$61)),$C$27*$C$11*$D$61)","v":""},"cfs"]
[null,null,"Rainfall Intensity at Regional Tc, I =",{"$f":"IF(I57=10,\"\",($C$19*$C$22/($I$57+$C$20)^$C$21))","v":""},"inch/hr",null,null,"Peak Flowrate, Qp =",{"$f":"IF($C$27=\"\",IF($C$26=\"\",\"\",IF($D$62=\"\",\"\",$C$26*$C$11*$D$62)),$C$27*$C$11*$D$62)","v":""},"cfs"]
[null,null,"Rainfall Intensity at User-Defined Tc, I =",{"$f":"IF($I$58=\"\",\"\",($C$19*$C$22/($I$58+$C$20)^$C$21))","v":""},"inch/hr",null,null,"Peak Flowrate, Qp =",{"$f":"IF($C$27=\"\",IF($C$26=\"\",\"\",IF($D$63=\"\",\"\",$C$26*$C$11*$D$63)),$C$27*$C$11*$D$63)","v":""},"cfs"]
[null,{"$f":"IF($BA$103=\"\",\"\",$BA$103)","v":"Calculated values for Tc & Qp are based on overide values entered for C & C-5."}]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[]
[null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,"Calculated values for Tc & Qp are based on overide values entered for C & C-5."]

{"sheet":"Design Info","index":3,"n_rows":54,"n_cols":21,"rows_kept":54,"cut":false,"hidden":false,"merged":[[32,18,32,19],[33,18,33,19],[38,18,38,19],[39,18,39,19],[34,18,34,19],[35,18,35,19],[36,18,36,19],[37,18,37,19],[26,18,26,19],[27,18,27,19],[28,18,28,19],[29,18,29,19],[30,18,30,19],[31,18,31,19],[20,18,20,19],[21,18,21,19],[22,18,22,19],[23,18,23,19],[24,18,24,19],[25,18,25,19],[14,18,14,19],[15,18,15,19],[16,18,16,19],[17,18,17,19],[18,18,18,19],[19,18,19,19],[28,7,28,12],[28,1,28,6],[27,1,27,6],[27,7,27,12],[9,18,11,19],[9,15,11,17],[22,3,22,6],[21,3,21,6],[12,18,12,19],[13,18,13,19]]}
["Runoff Coefficient vs. Watershed Imperviousness "]
[]
[null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,"I.    One-hr Precipitation Values for Metro Denver Area"]
[]
["Based on Runoff Coefficient estimating equation published by Urbonas, et.al. (1990) & WEF (1998)",null,null,null,null,null,null,null,null,null,null,null,null,null,null,"Return period in years",2,5,10,50,100]
[null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,"Depth in inches",0.93,1.35,1.61,2.2000000000000002,2.6]
["Basic equation for NRCS Soil Types C & D: "]
[null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,"II.   Recommended Runoff Coefficients for Metro Denver"]
["CCD = KCD + (0.858*i3 - 0.786*i2 + 0.774*i + 0.04) "]
[null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,"Land Use  or Surface Characteristics",null,null,"Percent Imper-viousness"]
["Basic equation for NRCS Soil Type A: "]
[]
["CA = KA + (1.31*i3 - 1.44*i2 + 1.135*i - 0.12)   in which use values for CA > 0",null,null,null,null,null,null,null,null,null,null,null,null,null,null," Business:"]
[null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,"     Commercial areas",null,null,95]
["in which:"," i    =  Ia/100, imperviousness ratio",null,null,null,null,null,null,null,null,null,null,null,null,null,"     Neighborhood areas",null,null,85]
[null,"Ia   = watershed imperviousness in percent",null,null,null,null,null,null,null,null,null,null,null,null,null,"Residential:"]
[null,"CA = Runoff Coefficient for NRCS Soil Type A",null,null,null,null,null,null,null,null,null,null,null,null,null,"     Single-family",null,null,"*"]
[null,"KA = Correction factor for CA when the storm return period is greater than 2-years ",null,null,null,null,null,null,null,null,null,null,null,null,null,"     Multiunit (detached)",null,null,60]
[null,"CCD = Runoff Coefficient for NRCS Soil Types C and D",null,null,null,null,null,null,null,null,null,null,null,null,null,"     Multiunit (attached)",null,null,75]
[null,"KCD = Correction factor for CCD when the storm return period is greater than 2-years ",null,null,null,null,null,null,null,null,null,null,null,null,null,"     Half-acre lot or larger",null,null,"*"]
[null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,"     Apartments",null,null,80]
[null,null,null,"Values of Correction Factors  KCD & KA",null,null,null,null,null,null,null,null,null,null,null,"Industrial:"]
[null,"NRCS",null,"Storm Return Period",null,null,null,null,null,null,null,null,null,null,null,"     Light areas",null,null,80]
[null,"Soil Types","2-yr","5-yr","10-yr","25-yr","50-yr","100-yr",null,null,null,null,null,null,null,"     Heavy areas",null,null,90]
[null,"C & D",0,"[-0.10*i+0.11]","[-0.18*i+0.21]","[-0.28*i+0.33]","[-0.33*i+0.40]","[-0.39*i+0.46]",null,null,null,null,null,null,null,"Parks, cemeteries:",null,null,5]
[null,"A",0,"[-0.08*i+0.09]","[-0.14*i+0.17]","[-0.19*i+0.24]","[-0.22*i+0.28]","[-0.25*i+0.32]",null,null,null,null,null,null,null,"Playgrounds:",null,null,10]
[null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,"Schools:",null,null,50]
[null,"Values of Runoff Coefficient CCD",null,null,null,null,null,"Values of Runoff Coefficient CA",null,null,null,null,null,null,null,"Railroad yard areas:",null,null,15]
["Imperv.","Type C and D NRCS Hydrologic Soil Groups",null,null,null,null,null,"Type A NRCS Hydrologic Soils Group",null,null,null,null,null,null,null,"Undeveloped areas:"]
["Ratio ( i)","2-yr","5-yr","10-yr","25-yr","50-yr","100-yr","2-yr","5-yr","10-yr","25-yr","50-yr","100-yr",null,null,"     Historical Flow Analysis",null,null,2]
[0,{"$f":"0.858*$A31^3-0.786*$A31^2+0.774*$A31+0.04","v":0.04},{"$f":"(-0.1*$A31+0.11)+$B31","v":0.15},{"$f":"(-0.18*$A31+0.21)+$B31","v":0.25},{"$f":"(-0.28*$A31+0.33)+$B31","v":0.37},{"$f":"(-0.33*$A31+0.4)+$B31","v":0.44},{"$f":"(-0.39*$A31+0.46)+$B31","v":0.5},{"$f":"1.31*$A31^3-1.44*$A31^2+1.135*$A31-0.12","v":-0.12},{"$f":"(-0.08*$A31+0.09)+$H31","v":-0.03},{"$f":"(-0.14*$A31+0.17)+$H31","v":5.0000000000000017E-2},{"$f":"(-0.19*$A31+0.24)+$H31","v":0.12},{"$f":"(-0.22*$A31+0.28)+$H31","v":0.16000000000000003},{"$f":"(-0.25*$A31+0.32)+$H31","v":0.2},null,null,"     Greenbelts, agricultural"]
[{"$f":"A31+0.05","v":0.05},7.6842250000000001E-2,0.18184224999999998,0.27784224999999996,0.39284225,0.46034225000000001,0.51734225,-6.6686250000000002E-2,1.9313749999999991E-2,9.6313750000000004E-2,0.16381374999999998,0.20231375000000001,0.24081374999999999,null,null,"     Off-site flow analysis",null,null,45]
[0.1,0.110398,0.210398,0.302398,0.41239799999999999,0.47739799999999999,0.53139800000000004,-1.9589999999999996E-2,6.2409999999999993E-2,0.13641,0.20140999999999998,0.23841000000000001,0.27540999999999999,null,null,"     (when land use not defined)"]
[0.15000000000000002,0.14131075000000001,0.23631075000000001,0.32431074999999998,0.42931075000000007,0.49181075000000007,0.54281075000000001,2.2271250000000048E-2,0.10027125000000005,0.17127125000000007,0.23377125000000004,0.26927125000000007,0.30477125000000005,null,null,"Streets:"]
[0.2,0.17022400000000001,0.26022400000000001,0.34422399999999997,0.44422400000000006,0.50422400000000001,0.55222400000000005,5.9879999999999989E-2,0.13388,0.20188,0.26188,0.29588000000000003,0.32988000000000001,null,null,"     Paved",null,null,100]
[0.25,0.19778125000000002,0.28278124999999998,0.36278125,0.45778125000000003,0.51528125000000002,0.56028125000000006,9.4218750000000018E-2,0.16421875000000002,0.22921875000000003,0.28671875000000002,0.31921875000000005,0.35171875000000002,null,null,"     Gravel (packed)",null,null,40]
[0.3,0.22462599999999999,0.30462600000000001,0.38062600000000002,0.47062599999999999,0.52562600000000004,0.56762599999999996,0.12626999999999999,0.19227,0.25427,0.30926999999999999,0.34027000000000002,0.37126999999999999,null,null,"Driveways and sidewalks:",null,null,90]
[0.35,0.25140174999999998,0.32640174999999999,0.39840175,0.48340174999999996,0.53590175000000007,0.57490174999999999,0.15701625000000002,0.21901625000000002,0.27801625000000002,0.33051625000000001,0.36001625000000004,0.38951625000000001,null,null,"Roofs:",null,null,90]
[0.39999999999999997,0.278752,0.34875200000000001,0.41675200000000001,0.49675200000000003,0.54675200000000002,0.58275200000000005,0.18744,0.24543999999999999,0.30144000000000004,0.35143999999999997,0.37944,0.40744000000000002,null,null,"     Lawns, sandy soil",null,null,0]
[0.44999999999999996,0.30732024999999996,0.37232024999999996,0.43632024999999997,0.51132025000000003,0.55882025000000002,0.59182025000000005,0.21852374999999996,0.27252374999999995,0.32552375,0.37302374999999999,0.39952375000000001,0.42602374999999998,null,null,"     Lawns, clayey soil",null,null,0]
[0.49999999999999994,0.33774999999999994,0.39774999999999994,0.45774999999999993,0.52774999999999994,0.57274999999999998,0.6027499999999999,0.25124999999999992,0.30124999999999991,0.35124999999999995,0.39624999999999994,0.42124999999999996,0.44624999999999992,null,null,"*Refer to Figures RO-3 through RO-5 in Runoff Chapter "]
[0.54999999999999993,0.37068474999999995,0.42568474999999995,0.48168474999999994,0.54668474999999994,0.58918475000000003,0.61618474999999995,0.28660125000000003,0.33260125000000001,0.37960125000000006,0.42210125000000004,0.44560125000000006,0.46910125000000003,null,null,"of USDCM."]
[0.6,0.40676799999999996,0.45676799999999995,0.508768,0.56876799999999994,0.60876799999999998,0.632768,0.32555999999999996,0.36755999999999994,0.41155999999999998,0.45155999999999996,0.47355999999999998,0.49556]
[0.65,0.44664324999999999,0.49164324999999998,0.53964325000000002,0.59464324999999996,0.63214324999999993,0.65314325000000006,0.36910875000000004,0.40710875000000002,0.44810875000000006,0.48560875000000003,0.50610875000000011,0.52660875000000007]
[0.70000000000000007,0.490954,0.53095400000000004,0.57495399999999997,0.62495400000000001,0.65995399999999993,0.67795399999999995,0.4182300000000001,0.45223000000000008,0.49023000000000011,0.52523000000000009,0.5442300000000001,0.56323000000000012]
[0.75000000000000011,0.54034375000000012,0.57534375000000015,0.61534375000000008,0.66034375000000012,0.69284375000000009,0.7078437500000001,0.4739062500000002,0.50390625000000022,0.53890625000000014,0.57140625000000012,0.58890625000000019,0.60640625000000015]
[0.80000000000000016,0.59545600000000021,0.62545600000000023,0.66145600000000015,0.70145600000000019,0.73145600000000011,0.74345600000000012,0.53712000000000015,0.56312000000000018,0.59512000000000009,0.62512000000000012,0.64112000000000013,0.65712000000000015]
[0.8500000000000002,0.65693425000000027,0.6819342500000003,0.71393425000000021,0.74893425000000025,0.77643425000000021,0.78543425000000022,0.60885375000000042,0.63085375000000043,0.65985375000000035,0.68735375000000043,0.70185375000000039,0.71635375000000034]
[0.90000000000000024,0.72542200000000034,0.74542200000000036,0.77342200000000028,0.8034220000000003,0.82842200000000021,0.83442200000000022,0.69009000000000054,0.70809000000000055,0.73409000000000046,0.75909000000000049,0.7720900000000005,0.78509000000000051]
[0.95000000000000029,0.80156275000000055,0.81656275000000056,0.84056275000000047,0.86556275000000049,0.88806275000000046,0.89106275000000046,0.78181125000000062,0.79581125000000064,0.81881125000000055,0.84131125000000062,0.85281125000000058,0.86431125000000053]
[1.0000000000000002,0.88600000000000045,0.89600000000000046,0.91600000000000037,0.93600000000000039,0.95600000000000041,0.95600000000000041,0.88500000000000056,0.89500000000000057,0.91500000000000048,0.9350000000000005,0.94500000000000051,0.95500000000000052]
[null,"Notes:   ","For Type B Soils, use the average of coefficients CCD and CA. "]
[null,null,"When the Runoff Coefficient in above table is < 0, use 0."]
[null,null,"When compositing the Runoff Coefficient for different soil types, use  the table values above regardless if they are < 0."]

{"sheet":"Notation","index":4,"n_rows":19,"n_cols":3,"rows_kept":19,"cut":false,"hidden":false,"merged":[]}
[]
[null,"List of Variables"]
[]
[]
[null,"A =","watershed area in acres"]
[null,"C =","runoff coefficient"]
[null,"C1, C2, and C3 =","coefficients in IDF formula"]
[null,"C5 =","5-yr runoff coefficient"]
[null,"I =","rainfall intensity in inches/hour"]
[null,"ID =","user defined identification number"]
[null,"L =","flow length in ft"]
[null,"S =","slope for flow length in ft/ft"]
[null,"P1 =","one hour precipitation value in inches"]
[null,"Tc =","time of concentration in minutes"]
[null,"Td =","design rainfall duration in minutes"]
[null,"Tf =","flow time in minutes"]
[null,"Tr =","return period in years"]
[null,"Qp =","peak runoff rate in cfs"]
[null,"V =","flow velocity in ft/second"]