hydrograph

HYDROGRAPHS / SCS CURVE NUMBER METHODRunoff

Runoff is the result of a precipitation eventStreamflow is baseflow + runoff that makes it to the stream channel.Runoff vs. Streamflow

What is a watershed?A watershed is the entire drainage area of a stream or river, from which the surface and groundwater leave at a single point. Watersheds are defined by surface topography (elevation).River basins are drained by large rivers with many tributaries are typically calledWatersheds are drained by tributaries or small streams

Watershed

Watershed Factors that Affect Surface RunoffTopographySurface runoff occurs in the direction of land slopePerpendicular to the contour linesLand slope has a significant effect on water velocityOverland flowChannel flow

Elevation Contours with Surface Runoff

Watershed Factors that Affect Surface RunoffWatershed shapeCircular watershed higher rates of runoffRunoff from different points reach outlet at same timeElongated watershed lower rates than circularDownstream tributaries reach outlet firstSoilControls the infiltration processLand useVegetative cover reduces runoff

Watershed Shapes

Watershed Factors that Affect Surface RunoffLand useVegetative cover reduces runoffImproves soil structureDepletes soil moisture dry antecedent moistureBare soil increased runoffPoor structureLess permeable surface sealingFine soil particles washed into larger soil pores

Flow measurement

How is flow measured?

Surface Runoff CharacteristicsHydrograph plot of runoff rates vs. timeExcess rainfall rainfall that runs offDepth measurement over watershedSimilar to rainfall measurementsExcess rainfall depth (ft) x area (ft2) = runoff volume (ft3)Excess rainfall volume = surface runoff volume

Time (T)Stream Hydrograph

Storm Hydrograph(Surface runoff only / base flow removed)Discharge (Q)QpTime (T)Peak dischargeRising limbRecession limbTbase

Storm Hydrograph(Surface runoff only / base flow removed)Discharge (Q) in cfsTime (T) in HrArea under the curve = surface runoff volume[Q(ft3/sec) x T(sec) = Volume (ft3)]Triangle #1: V1 = (100 x 3600) / 2 = 180,000 ft3Triangle #2: V2 = (100 x (14,400 3,600)) / 2 = 540,000 ft3Total Surface Runoff Volume = V1 + V2 = 720,000 ft310014(3600 sec)(14,400 sec)#2#1

Surface Runoff AnalysisTotal rainfall = 4.0 in.Watershed area = 132.2 ac = 5,760,000 ft2Total surface runoff = 720,000 ft3From the hydrograph analysisRunoff depth over watershed = excess rainfallDepth = 720,000 ft3 / 5,760,000 ft2 = 0.125 ft = 1.5 in.Average runoff rate = 1.5 in. / 4 hr = 0.38 in./hrGet the 4-hr from the hydrograph (x-axis)

Runoff HydrographsComplete Runoff Hydrograph Contains:Runoff Volume-Area under the hydrographPeak Flow Rates-maximum flow or peak of the runoff hydrograph.A complete time history of the flow.

For small watersheds we ignore baseflow so that:Runoff=effective rainfall=precipitation - abstractions

Development of RO HydrographsMost often interested in hydrographs at the watershed outlet (and possibly some selected points in the watershed).We modify the rainfall hyetograph to reflect watershed characteristics.The volume under the effective rainfall hyetograph is equal to the volume of surface runoff.

Hydrograph componentsqp is the maximum flow rate on the hydrographtp (time to peak) is the time from the start of they hydrograph to qp.tb (base time) is the total time duration of the hydrograph.

Comparison of Urban andForested Hydrographs

Comparison of Upstream and Downstream Hydrographs

Effective RainfallTHE SCS CURVE NUMBER APPROACH

Effective RainfallRainfall that becomes runoff.Effective Rainfall = Precipitation Initial AbstractionsAlso called Rainfall Excess.Effective Rainfall=Rainfall Excess=Runoff

SCS Curve Number Approach The most commonly used methodSCS method for rainfall excesscombines infiltration losses and other initial losses (interception / surface storage / etc)estimate of excess rainfall (surface runoff)

Q = [(P - 0.2S)^2] / (P + 0.8S) for P > 0.2SQ = accumulated runoff volumeP = accumulated precipitationS = max soil water retention constantS = (1000 / CN) - 10 (Q,P and S = in.)S = (25400 / CN) -254 (Q,P & S = mm)

The 0.2S FactorThe precipitation must exceed 0.2S before runoff occurs0.2S = Initial abstraction (Ia) that includes:Surface depressionsVegetation interceptionEvaporationInfiltrationS = Potential maximum retention after surface runoff begins

Hydrologic Soil Groups (HSG)4 hydrologic soil groups => A,B,C,DA = sand, loamy sand or sandy loamB = silt loam or loamC = sandy clay loamD = clay loam, silty clay loam, sandy clay, silty clay or claybased on surface soil texturewhen choosing a group must consider:compaction by heavy equipment, exposure of subsoil, etc.

HSGs based on Saturated Hydraulic Conductivity (Ksat)A soil (high infiltration rates)Ksat > 0.30 in./hrB soil (moderate infiltration rates)0.15 in./hr < Ksat < 0.30 in./hrC soil (slow infiltration rates)0.05 in./hr < Ksat < 0.15 in./hrD soil (very slow infiltration rates)Ksat < 0.05 in./hrSee Appendix D for a list of the most common soils in each state with HSG type (A, B, C or D)

Curve Numbers (CN) and Antecedent Moisture ConditionsCN = SRO potential of areaTable 5.1 (very limited)See other references for more extensive listingCN's developed for land use / land treatment combinationsAntecedent moisture conditions I, II, IIIcondition I => initially dry soilcondition II => average soil moisturecondition II => Table 5.1condition III=> initially wet soil

Curve NumberA parameter that combines soil type and land use to estimate runoff potential.

Based on the Hydrologic Soil Group (HSG), land use and condition.

Range between 0 and 100. The greater the curve number, the greater the potential for runoff.

Impervious areas and water surfaces are assigned curve numbers of 98-100.

Curve Numbers

Curve Numbers (CN) and Antecedent Moisture ConditionsCN for conditions I and III can be adjusted using condition II CN'sSee Table 5.2Adjustment based on 5-day antecedent rainSee page 145 for detailsCN develop from experimental plotslots of measured rainfall / runoff datathroughout the U.S.CN's correlated w/ land useGood for higher infiltration ratesNot so good for lower infiltration rates

Curve Numbers for Impervious SurfacesImpervious areasImpervious areas ==> CN = 98 to 100expressed as % of total areadirectly connected => flow directly to a drainage system (gutters, sewers, etc)

Area Weighted Curve NumberMixed land uses and HSG'sCalculate an area-weighted CNGet a single CN for the entire areaCN = Si AiCNi) / (Si Ai)CNi = CN for the part of catchment having area Ai

Example ProblemGiven:Precipitation (P) = 4.04 in.A watershed that has:35% cultivated with a D soil group30% meadow with a B soil group35% thin forest with a C soil groupRequired:Calculate the surface runoff (excess rainfall)

Watershed with Land Use % and HSGs Listed

Example ProblemFind the curve numbersUseHSG%CN*Cultivated D3591Meadow B3058Thin Forest C3577*Table 5.1 text (reference is important)

Calculate a weighted CNWeights based on % areaCNavg = 0.35(91) + 0.30(58) + 0.35(77)CN avg = 76.2 = 76

Example ProblemCalculate the S termS = 1000 / CN 10 = (1000 / 76) 10S = 3.16 in.

Check to see if P > 0.2S0.2S = 0.2(3.16) = 0.63 in. P > 0.2S

Calculate surface runoff (Q)Q = [(P - 0.2S)^2] / (P + 0.8S)Q = [(4.04 0.2(3.16)]2 / [4.04 + ((0.8)3.16)]Q = 1.77 in.For a rainfall event = 4.04 in. on the given watershed with average soil moisture conditions

Repeat for all Rainfall Blocks.

Rainfall Hyetograph

Chart4

0

477.3008373727

2867.2533846902

5805.9264184831

7532.1757689884

7656.3325641436

6669.7014382484

5223.3094098887

3783.8665077444

2582.6932971432

1681.9637978282

1054.5361884687

640.741335853

379.196218895

219.4333308726

124.550098132

69.5141382742

38.2275993779

20.7486892632

11.1308851879

5.9090133251

3.1073560153

1.6200943506

0.8380970045

0.4304691732

0.219653076

Time (hrs)

Flow (cfs)

8-hr 50-yr Runoff Hydrograph for BCS

Chart3

0000

5.7932950768477.30083737271133.7853954677197.9254016073

119.25948246262867.25338469026810.90364425371188.9823634052

777.06351669465805.926418483113791.45826910882407.5807710836

3367.2843400037532.175768988417892.00901046513123.4156685328

11300.56812710387656.332564143618186.93235874563174.900563633

24463.25331453586669.701438248415843.27847493662765.7679023413

36707.53560022345223.309409888712407.50374028072165.983236824

43259.5970468543783.86650774448988.23603263481569.0802100749

43477.87658844822582.69329714326134.9566394891070.9820055613

38819.85911843381681.96379782823995.3543768749697.4707230906

31550.04155333161054.53618846872504.9562788519437.2912894119

23772.5381949608640.7413358531522.0236630245265.7003220928

16846.8858782636379.196218895900.7466598347157.243729816

11355.0711221729219.4333308726521.244226579790.9938276623

7342.7913245836124.550098132295.857604280451.6479885698

4586.500146657969.5141382742165.124610272328.8258738682

2782.102576146338.227599377990.806238926915.8520839834

1645.835069771720.748689263249.28665323798.6039921444

952.820886306611.130885187926.440420964.6157156002

541.33008764715.909013325114.0363319842.4503284803

302.50934131853.10735601537.38124594141.2885472623

166.59911222551.62009435063.84838904550.6718149223

90.56531754460.83809700451.99082438010.3475390639

48.66285177860.43046917321.0225409710.1785054148

25.87522052430.2196530760.52176621140.0910849508

13.6273687768

7.0964256939

3.6304721209

1.6226063751

0.5664174991

0.2241156297

0.0678808139

0

Total Runoff

Unit Hydrograph

Block 5

Block 7

Time (Hours)

Flow (cfs)

Total Runoff Hydrograph and Unit Hydrograph for 8-hr 50-yr Storm

Sheet8

CN91

S0.989

0.2 S0.198

8-hr 50-yr Storm

P249.8inAccumulatedIncremental

IncrementalAccumulatedEffectiveEffective

TimeP/P24PTimePPRainfallRainfall

8.00.1141.120.00.000.000.000.00

9.00.1461.431.00.310.310.010.01

10.00.1891.852.00.420.730.190.18

11.00.2502.453.00.601.330.610.42

12.00.5004.904.02.453.782.812.20

13.00.7507.355.02.456.235.192.38

14.00.8117.956.00.606.835.770.59

15.00.8548.377.00.427.256.190.41

16.00.8868.688.00.317.576.500.31

7.576.50

Sheet7

CN80

S2.5

0.2 S0.5

8-hr 50-yr Storm




8.00.1141.120.00.000.000.000.00

9.00.1461.431.00.310.310.000.00

10.00.1891.852.00.420.730.020.02

11.00.2502.453.00.601.330.210.19

12.00.5004.904.02.453.781.861.66

13.00.7507.355.02.456.233.992.13

14.00.8117.956.00.606.834.540.55

15.00.8548.377.00.427.254.930.39

16.00.8868.688.00.317.575.220.29

7.575.22

Sheet5

8-hr 50-yr Storm in Bryan-College Station

P24=9.8in

ABCDEFGH

AccumulatedIncremental



8.00.1141.120.00.000.00

9.00.1461.431.00.310.31

10.00.1891.852.00.420.73

11.00.2502.453.00.601.33

12.00.5004.904.02.453.78

13.00.7507.355.02.456.23

14.00.8117.956.00.606.83

15.00.8548.377.00.427.25

16.00.8868.688.00.317.57

7.57

A-BCoordinates for 8 most intense hours (1 hour increments) of the SCS Type III storm (Table 3.4)

CColumn B X P24 from 50-yr 24-hr storm for BCS (Appendix 3A)

DTime from beginning of the 8 hour storm

EDifferencing of Column C to get Incremental P starting with 0 rain at 0 time. (i.e. E9=C9-C8)

FAccumulation from Column E (F9=F8+E9)

G

H

Sheet10

Total Runoff Hydrograph for 8-hr 50-yr Storm

Total

UnitRunoff

TimeHydrograph0.0120.1770.4172.2032.3750.5870.4150.309Hydrograph

0.00.00

1.0477.30

2.02867.25

3.05805.93

4.07532.18

5.07656.33

6.06669.70

7.05223.31

8.03783.87

9.02582.69

10.01681.96

11.01054.54

12.0640.74

13.0379.20

14.0219.43

15.0124.55

16.069.51

17.038.23

18.020.75

19.011.13

20.05.91

21.03.11

22.01.62

23.00.84

24.00.43

25.00.22

26.0

27.0

28.0

29.0

30.0

31.0

32.0

33.0

Sheet4


Total

UnitRunoff


0.00.000.000.00

1.0477.305.790.005.79

2.02867.2534.8084.460.00119.26

3.05805.9370.47507.36199.240.00777.06

4.07532.1891.421027.351196.861051.650.003367.28

5.07656.3392.931332.812423.526317.521133.790.0011300.57

6.06669.7080.951354.783144.1012792.406810.90280.120.0024463.25

7.05223.3163.401180.203195.9216595.9013791.461682.73197.930.0036707.54

8.03783.8745.93924.262784.0816869.4617892.013407.371188.98147.5043259.60

9.02582.6931.35669.552180.3314695.5818186.934420.472407.58886.0943477.88

10.01681.9620.42457.001579.4711508.7015843.284493.333123.421794.2438819.86

11.01054.5412.80297.621078.078337.1212407.503914.303174.902327.7231550.04

12.0640.747.78186.60702.095690.548988.243065.442765.772366.0923772.54

13.0379.204.60113.38440.193705.936134.962220.672165.982061.1816846.89

14.0219.432.6667.10267.462323.503995.351515.731569.081614.1911355.07

15.0124.551.5138.83158.291411.772504.96987.111070.981169.357342.79

16.069.510.8422.0491.60835.501522.02618.88697.47798.154586.50

17.038.230.4612.3051.99483.49900.75376.04437.29519.792782.10

18.020.750.256.7629.02274.43521.24222.54265.70325.891645.84

19.011.130.143.6715.96153.16295.86128.78157.24198.01952.82

20.05.910.071.978.6684.23165.1273.1090.99117.19541.33

21.03.110.041.054.6545.7290.8140.8051.6567.81302.51

22.01.620.020.552.4724.5349.2922.4328.8338.49166.60

23.00.840.010.291.3013.0226.4412.1815.8521.4890.57

24.00.430.010.150.686.8514.046.538.6011.8148.66

25.00.220.000.080.353.577.383.474.626.4125.88

26.00.040.181.853.851.822.453.4413.63

27.00.090.951.990.951.291.837.10

28.00.481.020.490.670.963.63

29.00.520.250.350.501.62

30.00.130.180.260.57

31.00.090.130.22

32.00.070.07

33.00.00

304335.05

Sheet6

8-hr 50-yr Storm for BCS

CN(III)91

S0.989

0.2 S0.1978



TimeP/P24PPPRainfallRainfall

8.00.1141.120.000.000.0000

9.00.1461.430.310.310.0120.012

10.00.1891.850.420.730.1890.177

11.00.2502.450.601.330.6070.417

12.00.5004.902.453.782.8102.203

13.00.7507.352.456.235.1852.375

14.00.8117.950.606.835.7720.587

15.00.8548.370.427.256.1870.415

16.00.8868.680.317.576.4960.309

7.576.496

Sheet1


CN(III)91tp4.57

S0.989qp7777.89

0.2 S0.1978K3.78



TimeP/P24PPPRainfallRainfallTimeRunoff

8.00.1141.120.000.000.00000.00

9.00.1461.430.310.310.0120.0121.0477.3008373727

10.00.1891.850.420.730.1890.1772.02867.2533846902

11.00.2502.450.601.330.6070.4173.05805.9264184831

12.00.5004.902.453.782.8102.2034.07532.1757689884

13.00.7507.352.456.235.1852.3755.07656.3325641436

14.00.8117.950.606.835.7720.5876.06669.7014382484

15.00.8548.370.427.256.1870.4157.05223.3094098887

16.00.8868.680.317.576.4960.3098.03783.8665077444

7.576.4969.02582.6932971432

10.01681.9637978282

11.01054.5361884687

12.0640.741335853

13.0379.196218895

14.0219.4333308726

15.0124.550098132

16.069.5141382742

17.038.2275993779

18.020.7486892632

19.011.1308851879

20.05.9090133251

21.03.1073560153

22.01.6200943506

23.00.8380970045

24.00.4304691732

25.00.219653076

Sum (qi)=46850.7265918001

Chart1

0

0.3136

0.4214

0.5978

2.45

2.45

0.5978

0.4214

0.3136

Time (hrs)

Precipitation

Rainfall Hyetograph for 8-hr 50-yr Storm for BCS

Chart2

0

0.0121376177

0.1769488979

0.4174224299

2.2033347363

2.375410447

0.5868778926

0.4146764181

0.3090364821

Time (Hrs)

Flow (in)

Effective Rainfall Hyetograph for BCS for 8-hr 50-yr Storm Using SCS Curve Number Method

Sheet2

Incremental

IncrementalEffective

PRainfall

00.0000.000

0.50.3140.012

1.50.4210.177

2.50.5980.417

3.52.4502.203

4.52.4502.375

5.50.5980.587

6.50.4210.415

7.50.3140.309

Sheet9


CN(III)91tp

S0.989qp

0.2 S0.1978K




8.00.1141.120.000.000.0000

9.00.1461.430.310.310.0120.012

10.00.1891.850.420.730.1890.177

11.00.2502.450.601.330.6070.417

12.00.5004.902.453.782.8102.203

13.00.7507.352.456.235.1852.375

14.00.8117.950.606.835.7720.587

15.00.8548.370.427.256.1870.415

16.00.8868.680.317.576.4960.309

7.576.496

Sheet3


CN(III)91tp

S0.989qp

0.2 S0.1978K




8.00.1141.120.000.000.0000

9.00.1461.430.310.310.0120.012

10.00.1891.850.420.730.1890.177

11.00.2502.450.601.330.6070.417

12.00.5004.902.453.782.8102.203

13.00.7507.352.456.235.1852.375

14.00.8117.950.606.835.7720.587

15.00.8548.370.427.256.1870.415

16.00.8868.680.317.576.4960.309

7.576.496

Effective Rainfall Hyetograph

Chart4

0

477.3008373727

2867.2533846902

5805.9264184831

7532.1757689884

7656.3325641436

6669.7014382484

5223.3094098887

3783.8665077444

2582.6932971432

1681.9637978282

1054.5361884687

640.741335853

379.196218895

219.4333308726

124.550098132

69.5141382742

38.2275993779

20.7486892632

11.1308851879

5.9090133251

3.1073560153

1.6200943506

0.8380970045

0.4304691732

0.219653076

Time (hrs)

Flow (cfs)

8-hr 50-yr Runoff Hydrograph for BCS

Chart3

0000

5.7932950768477.30083737271133.7853954677197.9254016073

119.25948246262867.25338469026810.90364425371188.9823634052

777.06351669465805.926418483113791.45826910882407.5807710836

3367.2843400037532.175768988417892.00901046513123.4156685328

11300.56812710387656.332564143618186.93235874563174.900563633

24463.25331453586669.701438248415843.27847493662765.7679023413

36707.53560022345223.309409888712407.50374028072165.983236824

43259.5970468543783.86650774448988.23603263481569.0802100749

43477.87658844822582.69329714326134.9566394891070.9820055613

38819.85911843381681.96379782823995.3543768749697.4707230906

31550.04155333161054.53618846872504.9562788519437.2912894119

23772.5381949608640.7413358531522.0236630245265.7003220928

16846.8858782636379.196218895900.7466598347157.243729816

11355.0711221729219.4333308726521.244226579790.9938276623

7342.7913245836124.550098132295.857604280451.6479885698

4586.500146657969.5141382742165.124610272328.8258738682

2782.102576146338.227599377990.806238926915.8520839834

1645.835069771720.748689263249.28665323798.6039921444

952.820886306611.130885187926.440420964.6157156002

541.33008764715.909013325114.0363319842.4503284803

302.50934131853.10735601537.38124594141.2885472623

166.59911222551.62009435063.84838904550.6718149223

90.56531754460.83809700451.99082438010.3475390639

48.66285177860.43046917321.0225409710.1785054148

25.87522052430.2196530760.52176621140.0910849508

13.6273687768

7.0964256939

3.6304721209

1.6226063751

0.5664174991

0.2241156297

0.0678808139

0

Total Runoff

Unit Hydrograph

Block 5

Block 7

Time (Hours)

Flow (cfs)

Total Runoff Hydrograph and Unit Hydrograph for 8-hr 50-yr Storm

Sheet8

CN91

S0.989

0.2 S0.198

8-hr 50-yr Storm




8.00.1141.120.00.000.000.000.00

9.00.1461.431.00.310.310.010.01

10.00.1891.852.00.420.730.190.18

11.00.2502.453.00.601.330.610.42

12.00.5004.904.02.453.782.812.20

13.00.7507.355.02.456.235.192.38

14.00.8117.956.00.606.835.770.59

15.00.8548.377.00.427.256.190.41

16.00.8868.688.00.317.576.500.31

7.576.50

Sheet7

CN80

S2.5

0.2 S0.5

8-hr 50-yr Storm




8.00.1141.120.00.000.000.000.00

9.00.1461.431.00.310.310.000.00

10.00.1891.852.00.420.730.020.02

11.00.2502.453.00.601.330.210.19

12.00.5004.904.02.453.781.861.66

13.00.7507.355.02.456.233.992.13

14.00.8117.956.00.606.834.540.55

15.00.8548.377.00.427.254.930.39

16.00.8868.688.00.317.575.220.29

7.575.22

Sheet5

8-hr 50-yr Storm in Bryan-College Station

P24=9.8in

ABCDEFGH

AccumulatedIncremental



8.00.1141.120.00.000.00

9.00.1461.431.00.310.31

10.00.1891.852.00.420.73

11.00.2502.453.00.601.33

12.00.5004.904.02.453.78

13.00.7507.355.02.456.23

14.00.8117.956.00.606.83

15.00.8548.377.00.427.25

16.00.8868.688.00.317.57

7.57

A-BCoordinates for 8 most intense hours (1 hour increments) of the SCS Type III storm (Table 3.4)

CColumn B X P24 from 50-yr 24-hr storm for BCS (Appendix 3A)

DTime from beginning of the 8 hour storm

EDifferencing of Column C to get Incremental P starting with 0 rain at 0 time. (i.e. E9=C9-C8)

FAccumulation from Column E (F9=F8+E9)

G

H

Sheet10


Total

UnitRunoff


0.00.00

1.0477.30

2.02867.25

3.05805.93

4.07532.18

5.07656.33

6.06669.70

7.05223.31

8.03783.87

9.02582.69

10.01681.96

11.01054.54

12.0640.74

13.0379.20

14.0219.43

15.0124.55

16.069.51

17.038.23

18.020.75

19.011.13

20.05.91

21.03.11

22.01.62

23.00.84

24.00.43

25.00.22

26.0

27.0

28.0

29.0

30.0

31.0

32.0

33.0

Sheet4


Total

UnitRunoff


0.00.000.000.00

1.0477.305.790.005.79

2.02867.2534.8084.460.00119.26

3.05805.9370.47507.36199.240.00777.06

4.07532.1891.421027.351196.861051.650.003367.28

5.07656.3392.931332.812423.526317.521133.790.0011300.57

6.06669.7080.951354.783144.1012792.406810.90280.120.0024463.25

7.05223.3163.401180.203195.9216595.9013791.461682.73197.930.0036707.54

8.03783.8745.93924.262784.0816869.4617892.013407.371188.98147.5043259.60

9.02582.6931.35669.552180.3314695.5818186.934420.472407.58886.0943477.88

10.01681.9620.42457.001579.4711508.7015843.284493.333123.421794.2438819.86

11.01054.5412.80297.621078.078337.1212407.503914.303174.902327.7231550.04

12.0640.747.78186.60702.095690.548988.243065.442765.772366.0923772.54

13.0379.204.60113.38440.193705.936134.962220.672165.982061.1816846.89

14.0219.432.6667.10267.462323.503995.351515.731569.081614.1911355.07

15.0124.551.5138.83158.291411.772504.96987.111070.981169.357342.79

16.069.510.8422.0491.60835.501522.02618.88697.47798.154586.50

17.038.230.4612.3051.99483.49900.75376.04437.29519.792782.10

18.020.750.256.7629.02274.43521.24222.54265.70325.891645.84

19.011.130.143.6715.96153.16295.86128.78157.24198.01952.82

20.05.910.071.978.6684.23165.1273.1090.99117.19541.33

21.03.110.041.054.6545.7290.8140.8051.6567.81302.51

22.01.620.020.552.4724.5349.2922.4328.8338.49166.60

23.00.840.010.291.3013.0226.4412.1815.8521.4890.57

24.00.430.010.150.686.8514.046.538.6011.8148.66

25.00.220.000.080.353.577.383.474.626.4125.88

26.00.040.181.853.851.822.453.4413.63

27.00.090.951.990.951.291.837.10

28.00.481.020.490.670.963.63

29.00.520.250.350.501.62

30.00.130.180.260.57

31.00.090.130.22

32.00.070.07

33.00.00

304335.05

Sheet6


CN(III)91

S0.989

0.2 S0.1978



TimeP/P24PPPRainfallRainfall

8.00.1141.120.000.000.0000

9.00.1461.430.310.310.0120.012

10.00.1891.850.420.730.1890.177

11.00.2502.450.601.330.6070.417

12.00.5004.902.453.782.8102.203

13.00.7507.352.456.235.1852.375

14.00.8117.950.606.835.7720.587

15.00.8548.370.427.256.1870.415

16.00.8868.680.317.576.4960.309

7.576.496

Sheet1


CN(III)91tp4.57

S0.989qp7777.89

0.2 S0.1978K3.78




8.00.1141.120.000.000.00000.00

9.00.1461.430.310.310.0120.0121.0477.3008373727

10.00.1891.850.420.730.1890.1772.02867.2533846902

11.00.2502.450.601.330.6070.4173.05805.9264184831

12.00.5004.902.453.782.8102.2034.07532.1757689884

13.00.7507.352.456.235.1852.3755.07656.3325641436

14.00.8117.950.606.835.7720.5876.06669.7014382484

15.00.8548.370.427.256.1870.4157.05223.3094098887

16.00.8868.680.317.576.4960.3098.03783.8665077444

7.576.4969.02582.6932971432

10.01681.9637978282

11.01054.5361884687

12.0640.741335853

13.0379.196218895

14.0219.4333308726

15.0124.550098132

16.069.5141382742

17.038.2275993779

18.020.7486892632

19.011.1308851879

20.05.9090133251

21.03.1073560153

22.01.6200943506

23.00.8380970045

24.00.4304691732

25.00.219653076

Sum (qi)=46850.7265918001

Chart1

0

0.3136

0.4214

0.5978

2.45

2.45

0.5978

0.4214

0.3136

Time (hrs)

Precipitation

Rainfall Hyetograph for 8-hr 50-yr Storm for BCS

Chart2

0

0.0121376177

0.1769488979

0.4174224299

2.2033347363

2.375410447

0.5868778926

0.4146764181

0.3090364821

Time (Hrs)

Flow (in)

Effective Rainfall Hyetograph for BCS for 8-hr 50-yr Storm Using SCS Curve Number Method

Sheet2

Incremental

IncrementalEffective

PRainfall

00.0000.000

0.50.3140.012

1.50.4210.177

2.50.5980.417

3.52.4502.203

4.52.4502.375

5.50.5980.587

6.50.4210.415

7.50.3140.309

Sheet9


CN(III)91tp

S0.989qp

0.2 S0.1978K




8.00.1141.120.000.000.0000

9.00.1461.430.310.310.0120.012

10.00.1891.850.420.730.1890.177

11.00.2502.450.601.330.6070.417

12.00.5004.902.453.782.8102.203

13.00.7507.352.456.235.1852.375

14.00.8117.950.606.835.7720.587

15.00.8548.370.427.256.1870.415

16.00.8868.680.317.576.4960.309

7.576.496

Sheet3


CN(III)91tp

S0.989qp

0.2 S0.1978K




8.00.1141.120.000.000.0000

9.00.1461.430.310.310.0120.012

10.00.1891.850.420.730.1890.177

11.00.2502.450.601.330.6070.417

12.00.5004.902.453.782.8102.203

13.00.7507.352.456.235.1852.375

14.00.8117.950.606.835.7720.587

15.00.8548.370.427.256.1870.415

16.00.8868.680.317.576.4960.309

7.576.496

***************************************

hydrograph

Documents

volume of surface runoff

ft2total surface runoff

baseflow runoff

ft3total surface runoff

runoff volumearea

average runoff rate

watershed area

timeexcess rainfall