Example 3. The ordinates o fa 6-hour unit hydrograph o fa catchment is given below.Time (h)Ordinate39.1215182430364248of 6-h UH255085 125 160 185 160110603625Time (h)546069Ordinateof 6-h UH168 0Derive the flood hydrograph in the catchment due to the storm given below:Time from start of storm (h)Accumulated rainfall (cm)12183.511.016.5The storm loss rate (O index) for the catchment is estimated as 0.25 cm/h. The base flowcan be assumed to be 15 m³/s at the beginning and increasing by 2.0 m³/s for every 12hours till the end of the direct-runoff hydrograph.

to find - ordinate of flood hydrograph

Example 3. The ordinates o fa 6-hour unit hydrograph o fa catchment is given below. 36 Time (h) Ordinate 3 9 12 15 18 24 30 42 48 of 6-h UH 25 50 85 125 160 185 160 110 60 36 25 Time (h) Ordinate 54 60 69 of 6-h UH 16 8. Derive the flood hydrograph in the catchment due to the storm given below:

Example 3. The ordinates o fa 6-hour unit hydrograph o fa catchment is given below. 36 Time (h) Ordinate 3 9 12 15 18 24 30 42 48 of 6-h UH 25 50 85 125 160 185 160 110 60 36 25 Time (h) Ordinate 54 60 69 of 6-h UH 16 8. Derive the flood hydrograph in the catchment due to the storm given below:

Structural Analysis

6th Edition

ISBN:9781337630931

Author:KASSIMALI, Aslam.

Publisher:KASSIMALI, Aslam.

Chapter2: Loads On Structures

Section: Chapter Questions

Problem 1P

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6 The ordinates of a 6-h unit hydrograph are as given below: Time (b) 6-h UH 12 18 24 30 36 42 48 54 60 75 25 50 100 87.5 75 62.5 50 37.5 25 72 66 72 78 12.5 0 0 ordinates (m3/s) Calculate the resulting hydrograph (flood hydrograph) due to storm of rainfall excess of 2 cm during the first 6 hours and 4 cm during the second 6 hours interval. The base flow can be assumed to be 25 m³/s constant throughout.
A watershed of 37 km2 was subjected to a storm of 2-h duration from which the following information are recorded in Table Q3. a) Obtain a Unit Hydrograph for this watershed knowing that the base flow in the stream is estimated at 2 m3 /s. [10] b) Derive and plot 6-h Unit Hydrograph for the catchment area. Time (hours) 0 1 2 3 4 5 6 7 8 Discharge (m3 /s) 2 15 30 37 30 22 16 12 2
A watershed of (30+X) km2 was subjected to a storm of 2-h duration from which the following information are recorded in Table a) Obtain a Unit Hydrograph for this watershed knowing that the base flow in the stream is estimated at 2 m3/s. b) Derive and plot 6-h Unit Hydrograph for the catchment area. Time (hours) 0 12345678 Discharge (m3/s) 2 15 30 37 30 22 16 12 2
Problem 3 The table below contains the data for a one-hour unit hydrograph. Time Q (hr) (cfs/in) 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 0 145 246 359 979 432 246 134 65 32 0 (a) Determine the area of the watershed to which this unit hydrograph corresponds. Report your answer in acres. (b) Assume a very intense 3-hour storm occurs shortly after a rainy period, so the ground is very saturated. The runoff from the first one-hour interval of the storm totals 0.5 in., the runoff from the second one-hour interval is 2.5 in, and the runoff from the third one-hour interval totals 1.7 in. The baseflow during and after the storm is 80 cfs. Derive the storm hydrograph for this 3-hour storm. table that clearly indicates how you used the unit hydrograph, sample calculations Provide a with sufficient explanation, explanatory sketches, and a graph of the storm hydrograph. (c) Determine the peak discharge that will occur in the river if this 3-hour storm occurs.
How would you go about deriving a UH from a catchment for which data (catchment area, rainfall and discharge values) are available? Derive a hyetograph from the incident rainfall (losses do not need to be considered to derive a UH); Determine the UH using the formula "Ui = Qi/P" (for a single interval hyetograph) or using "deconvolution" (for a multiple interval hyetograph). Estimate direct runoff hydrograph by subtracting baseflow from observed stream flow data; Estimate the total runoff volume and the direct runoff depth over the catchment; Determine the UH ordinates using the formula "Unit hydrograph = Direct runoff hydrograph x 1/Direct runoff depth"; Estimate catchment losses and subtract these from the incident precipitation to obtain excess rainfall; the duration of the excess rainfall is used as the duration of the UH. Determine the precipitation volume for each time interval; Use UH superposition and proportionality principles to derive a direct unit hydrograph; Estimate…
A 6-hr UHG of a catchment basin is triangular shape with a peak flowrate of 175m3/sec at 36 from the beginning. The time of hydrograph base was 96hr. The catchment area equal to: 3012 km^2 3016 km^2 3024 km^2 3028 km^2
Separate the baseflow from the stream flow hydrograph using the straight-line method. What is the baseflow? Calculate the direct runoff hydrograph (DRH) and plot it as an x-y scatter plot. Time (hr) Discharge (cfs) 0.0 60 0.5 54 1.0 50 1.5 90 2.0 137 2.5 176 3.0 200 3.5 198 4.0 140 4.5 97 5.0 60 5.5 40 6.0 35 6.5 32 7.0 29 7.5 24 8.0 22 8.5 20 9.0 20 9.5 19 10.0 19 10.5 18 11.0 18 11.5 18 12.0 17
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Given the data below: Drainage area = 405 hectares Neglect base flow TIME Hr. 0 2 4 6 8 10 12 14 16 18 Determine the following a) Direct runoff depth (Dr) b) Unit hydrograph peak flow c) Effective duration ORDINATES OF FLOOD HYDROGRAPH cu.m/s 0 0.6 1.1 2.6 5.4 4 2.6 ft. 1.7 0.3 0 cm per cm of runoff ORDINATES OF 2HR UNIT HYDROGRAPH Per cm per runoff
Example 4. Following are the ordinates of a storm hydrograph of a river draining a catchment area of 423 km² due to a 6-h isolated storm. Derive the ordinates o f a 6-h unit hydrograph for the catchment Time from start of storm (h) -6 0 6 12 18 24 30 36 42 48 Discharge (m³/s) 10 10 30 87.5 115.5 102.5 85.0 71.0 59.0 47.5 Time from start of storm (h) 54 60 66 72 78 84 90 96 102 Discharge (m³/s) 39.0 31.5 26.0 21.5 17.5 15.0 12.5 12.0 12.0
2 %V9 li. 3 (9 This question requires one response per row The base flow for this direct runoff hydrograph is: 0 4 8h o Index = 0.135 cm/h Rainfall excess = 5.52 cm 30 25 20 15 Direct runoff 5.52 cm 10 A Base flow -6 0 12 18 24 30 36 42 48 54 60 66 Time in hours -6 8 5.52 48 Discharge (m/s) 3.26 cm 2.26cm