Traffic And Highway Engineering
5th Edition
ISBN: 9781133605157
Author: Garber, Nicholas J., Hoel, Lester A.
Publisher: Cengage Learning,
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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
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
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
A certain watershed in Region VIII with an area of 60 ha flat heavy soil is to be converted
into a mixed subdivision consisting of:
40% apartment dwelling areas
20% business neighborhood areas
20% playgrounds and parks
20% light industrial areas
Using the rational method, estimate the percent change in peak runoff flow rates before
and after the development.
Refer to the table below for the values of runoff coefficients.
Values of Runoff coefficients, C (Chow, 1962)
Runoff
coefficient, C
Runoff
coefficient, C
Type of drainage area
Type of drainage area
Lawns:
Sandy soil, flat, 2%
Sandy soil, average, 2–7%
Sandy soil, steep, 7%
Heavy soil, flat, 2%
Heavy soil, average, 2–7%
Heavy soil, steep, 7%
Industrial
0.05–0.10
0.10-0.15
0.15-0.20
0.13-0.17
0.18-0.22
0.25-0.35
0.50–0.80
0.60–0.90
0. 10-0.25
0.20-0.35
Light areas
Heavy areas
Parks, cemeteries
Playgrounds
Railroad yard areas
Unimproved areas
Streets:
Asphaltic
Concrete
0.20-0.40
Business:
Downtown areas
Neighborhood areas
0.10-0.30…
Chapter 16 Solutions
Traffic And Highway Engineering
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Similar questions
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- 2. 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_forwardA 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_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_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_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_forward
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