Traffic and Highway Engineering
5th Edition
ISBN: 9781305156241
Author: Garber, Nicholas J.
Publisher: Cengage Learning
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Question
Chapter 16, Problem 7P
To determine
The rate of runoff for a storm of 100-year frequency and average velocityfor 196-acre rural drainage area.
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Students have asked these similar questions
Calculate the runoff depth for the 100 year storm event over a catchment
basin using the SCS Runoff Method. The design rainfall for 100 year storm
event is 6 inches. NOTE: Round off your weighted CN to the nearest
WHOLE NUMBER.
SOIL GROUP
C
D
C
D
LAND USE
20%
15%
40%
25%
HINT: Determine first the weighted CN by weighted CN
CN to determine the runoff depth.
Σ(%land
use
CURVE NUMBER
94
93
83
80
X CN) then use the weighted
3. The figure below shows 5 different isohyets in a watershed. Find the average rainfall using the
isohyetal method
Given: The left-most side area (Zone A) can be assumed to receive a rainfall of 1 cm. The area between
the isohyets are given in the following table:
A
Zone
A
B
C
D
E
F
B
1 cm
D
E
1.5 cm
4 cm
Area (km²)
80
75
95
82
68
5
2.5 cm
3.5 cm
Problem 1. The following are the ordinates of the hydrograph flow from a catchment area of 770 km2 due to a 6-hr rainfall.
a. Derive the ordinates of the 6-hr unit hydrograph. Assume that the graph of the baseflow is linear with respect to time.
b. Plot the direct runoff hydrograph.
c. Determine the rainfall excess in terms of (i) volume in m3 and (2) depth in cm.
d. Plot the unit hydrograph.
Time from the
beginning of the
storm (hr)
0 6
12
18
24
30
36
42
48
54
60 66 72
Discharge
(cumecs)
40 65
215 360 400 350 270 205 145 100 70 50 42
Chapter 16 Solutions
Traffic and Highway Engineering
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- A catchment area is presented in the Figure 1. Six rainfall gauges A, B, C, D, E and F are spread over this watershed and nearby. The inter isohyets areas I, II, II, IV and V are given as 20, 50, 70, 90, and 10 km? respectively. All the rainfall and isohyets are given in cm. Estimate the mean precipitation over this catchment area using arithmetic mean and isohyetal methods.arrow_forward2. The Friends Creek watershed has five rainfall gauges at the locations shown in the figure below. Total rainfall recorded at each gauge during a storm event is listed in the table. + Friends Creek C E w B Gage Rainfall (cm) A B C D E 6.0 7.8 9.2 4.1 3.0 Compute the mean areal rainfall (in centimeters) for this storm using: (a) Arithmetic averaging (b) The Thiessen methodarrow_forwardFollowings are given for a watershed: Rational method coefficient C = 0.37 Time of concentration = 30 min Watershed Area = 4.7 km^2 Rainfall intensity is 1.8 cm/hr Part 1: CIA=? (Must show calculation details for Part 1) (For Parts 2 to 4, pick only one choice and fill that blank) Part 2: If rainfall duration is 15 min, the peak flowrate is: a. b. uncertain, but it is smaller than C. uncertain, but it is greater than Part 3: If rainfall duration is 30 min, the peak flowrate is: d. e. uncertain, but it is smaller than f. uncertain, but it is greater than Part 4: If rainfall duration is 60 min, the peak flowrate is: g. h. uncertain, but it is smaller than_ i. uncertain, but it is greater thanarrow_forward
- The ordinates of a 6h-UH of a watershed having a drainage area of 393 km^2 are given below. For a storm over the watershed having excess rainfall of 5 cm for the first six hours and 15 cm for the second six hours, compute the direct runoff hydrograph ordinates and plot the hydrograph. Compute the depth of direct runoff in cm. Assuming constant baseflow of 100 m^3/s, compute the storm hydrograph ordinates and plot the hydrograph. (List all the DRH ordinates in order, separated by a single space.)arrow_forwardIn the table below data for precipitation and runoff both in depths of cm are given for June during ten years from 2010 to 2018. Develop a linear equation relating precipitation and runoff.arrow_forwardA catchment has a runoff coefficient of 0.20, area = 1.5 km² with a general slope of 0.001 and maximum length of travel of overland flow of 1.25 km. Information on the storm of 50 years return period is given as follows: Duration (min) 15 30 45 60 80 Rainfall (mm) 40 60 75 100 120 Estimate the peak flow to be drained by a culvert for a 50 year stormarrow_forward
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