Name: Student #:__________________________
University of Toronto
Faculty of Applied Science and Engineering
Department of Civil Engineering
C1V250 - Hydrology and Hydraulics
Final Exam, April 21, 2017
Duration: 2 and V2 hrs
The test is 11 pages and graded out of 70 marks.
Test is closed book, only a non-progranirnable calculator, rulers and a two-sided 8 ½" x 11" aid
sheet is permitted. All work must be neat and legible. Show all your calculations and state any
assumptions. Answers are to be written in exam booklets. Your equation sheet must be
submitted with your exam at the end of the examination period.
F
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TERMS AND CONCEPTS
1. 16 marks] Define and describe 3 of the following (use sketches when appropriate):
Effective Rainfall
Field Capacity
Stage
Lysimeter
CONCEPTUAL QUESTIONS
14 mark] What are the two resistance factors caused by plants that affect evapotranspiration? Describe these two types of resistance factors and how they affect evapotranspiration rates. Use sketches where appropriate.
14 marksl What function do the weirs provide in the Humber River? Many of the weirs along the Humber River have trapezoidal notches removed from the center of the weir. Why was this done? Was this intervention successful? Why or why not?
14
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COMPUTATION QUESTIONS.
4. The stormwater management system of a proposed 1.8 ha commercial development needs
to be designed for a storm with a 25 year return period. The 25-year IDF curve is given
by:
830
- t + 33
Where i is the rainfall intensity in cm/hr and t is the storm duration in minutes. Local
regulations require a minimum time of concentration of 10 minutes. The development has a Manning's n for overland flow of 0.016, an average overland flow length of 90 m and an
average slope of 0.6%.
110 marks] Determine the flow rate that will govern the design of the storm sewer. The
time of concentration can be modelled using the kinematic wave equation.
18 marks] The developer is considering directing the runoff to a reservoir for storage. In order to size the reservoir you need to determine the total volume of runoff that needs
to be stored. Use the NRCS curve number method to estimate the total volume of runoff for a 2 hr design storm, assuming the soil has an average condition at the beginning of the design storm. An infiltration test on the soil shows that the minimum infiltration
rate is 2 mm/hr.
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5. Discharge data was recorded during a 2-hr rain event at the outlet of a 200 km2 watershed.
The data is plotted in Figure 1. The stream outflows into a 50 ha lake.
Hydrograph
900
800
700
600
500
.D 400
300
200
100
0 0 1 2 3 4 5 6 7 8 9 10 11
Time (hrs)
Figure 1 - 2-hr Streamfiow Hydrograph
(i) [15 marks] Create the hydrograph for a 7 hour, 4.5 mm rainfall event. You may draw
on Figure 1 on this page to show your work. Include a sketch that graphically represents your process using the graph paper provided in Figure 2 and label each series. Clearly
show all intermediary steps and calculations for creating this hydro,iraph.
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Figure 2- Graph Paper for Question 5 (i)
[4 marks] The municipality is considering diverting a portion of the river for a micro-
hydroelectric project. They require a 10 m3/s discharge through the diversion channel
for the project to be successful. They have designed a 3 m wide rectangular concrete
lined diversion channel with a slope of 0.1 % to be used to divert the water for this
project. What depth of channel is required to accommodate this discharge?
[2 marks] Will the flow in the channel designed above be sub-critical or supercritical
flow?
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6. A site consists entirely of a sandy loam soil and has 4 mm of depression storage. Assume
the initial moisture content is 0.09. Using the Green and An-pt Method,
[2 marks] Determine if and when ponding begins during the storm. 115 marks] Determine the incremental and cumulative runoff from the site
using the following design storm.
Interval (mm) Average Rainfall (mm/hr)
0-10 20 10-20 40 20-30 60 30-40 110 40-50 60 50-60 20
End of Exam
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Flow Wetted Hydraulic Shape Section Area A Perimeter P Radius R
77 (b + zy)y Trapezoidal y y(h+zy) b +2y1+z2 b+v1+z2
ZY Triangular
NI Z 7Y zy 2 2y v1 +
by Rectangular
E _
by b + b 2v
__-
A V
Wide flat I by b y
-b >>y--
bS
sin 0 Circular
(0— sinO ç -
Copynght 32O13 Pearson Education, publishing as Prentice Hall
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Table 16.5 Rational Runoff Coefficient
Urban Catchments
General Description C Surface C
City 0.7-0.9 Asphalt paving 0.7-0.9
Suburban business 0.5-0.7 Roofs 0.7-0.9
Industrial 0.5-0,9 Lawn heavy soil
>7° slope 0.25-0.35
Residential multiunits 0.6-0.7 2-70 0.18-0.22
Housing estates 0.4-0.6 <2° 0.13-0.17
Bungalows 0.3-0.5 Lawn sandy soil
>71 0.15-0.2
Parks, cemeteries 0.1-0.3 2-70 0.10-0.15
<20 0.05-0.10
Rural Catchments (less than 10 km2)
Ground Cover Basic Factor Corrections: Add or Subtract
Bare surface 0.40 Slope < 5%:-0.05
Grassland 0.35 Slope> 10%: +0.05
Cultivated land 0.30 Recurrence interval <20 yr: -0.05
Timber 0.18 Recurrence interval > SO yr: +0.05 Mean annual precipitation <600 mm: -0.03 Mean annual precipitation> 900 mm: +0.03
Source: Stephenson (1981).
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Table 4.6 Green-Ampt Infiltration Parameters
Wetting front soil Effective hydraulic
Soil texture class Porosity, 9 suction head, S1, cm conductivity, K, cm/h
Sand 0,437 4,95 11.78
(0.374-0.500) (0.97-25.36)
Loamy sand 0,437 6.13 2.99
(0.363-0.506) (1.35-27.94)
Sandy loam 0.453 11.01 1.09
(0.351-0.555) (2.67-45.47)
Loam 0.463 8.89 0.66
(0.375-0.551) (1.33-59.38)
Silt loam 0,501 16,68 0,34
(0.420-0.582) (2.92-95.39)
Sandy clay loam 0,398 21.85 0.15
(0.332-0.464) (4.42-108.0)
Clay loam 0.464 20.88 0.10
(0.409-0.519) (4.79-91.10)
Silty clay loam 0.471 27.30 0.10
(0.418-0.524) (5.67-131.50)
Sandy clay 0,430 23.90 0.06
(0.370-0.490) (4.08-140.2)
Silty clay 0,479 29.22 0.05
(0.425-0.533) (6.13-139.4)
Clay 0.475 31,63 0.03
(0.427-0,523) (6.39-156.5)
Source: Rawls and 8rakensiek (1983).
Table 4.10 Hydrologic Soil Groups
Minimum
Infiltration Rate
Group Range (rnm.hr) Texture'
A 7.62 11.43 Sand, loamy sand, or sandy loam
3.81 7.62 Silt loam or loam
C 1.27 3.81 Sandy clay loam
D 0 1.27 Clay loam, silty clay Foam, sandy clay, silty clay, or clay
a Reproduced from U.S..Soil Conservation Service (1986.
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Table 2-1 Runoff Curve Numbers for Selected Agricultural, Suburban, and Urban Land Use (Antecedent Moisture
Condition II; 0.25)
Land Use Description A
Hydrologic Soil
Group
B C D
Cultivated land' Without conservation treatment 72 81 88 91
With conservation treatment 62 71 78 81
Pasture or range land
Poor condition 68 79 86 89
Good condition 39 61 74 80
Meadow
Good condition 30 58 71 78
Wood or forest land
Thin stand, poor cover, no mulch 45 66 77 83
Good cover2 25 55 70 77
Open spaces, lawns, parks, golf courses, cemeteries, etc.
Good condition: grass cover on 75% or more of the area 39 61 74 80
Fair condition: grass cover on 50%-75% of the areai 49 69 79 84
Commercial and business areas (85% impervious) 89 92 94 95
Industrial districts (72% impervious) 81 88 91 93
Residential3
Average lot size Average % impervious4
1/8 ac or less 65 77 85 90 92
114 ac 38 61 75 83 87
1/3 ac 30 57 72 81 86
1/2 ac 25 54 70 80 85
lac 20 51 68 79 84
Paved parking lots, roofs, driveways, etc.5 98 98 98 98
Streets and roads
Paved with curbs and storm sewers5 98 98 98 98
Gravel 76 85 89 91
Dirt 72 82 87 89
Factor to convert runoff volume to depth
Unit of Runoff Ordinate
Unit of Time Base
Unit of Volume
Unit of Area
Unit of depth
K
m3/s day m3/s*day km2 mm 86.4 m3/s hour m2/s*-hr km2 mm 3.6
Conversions:
1 ha = 10,000 m2
1 nun = 0.039 in
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Table 14.4 Values of Manning's Roughness Coefficient'
Material Manning n
Closed conduit or built-up channel
1.1 Metal
Brass 0.01
Copper 0.011
Steel—welded 0.012
Steel—riveted 0.016
Cast iron—coated 0.013
Wrought iron—galvanized 0.016
Corrugated metal (storm drain) 0.024
1.2 Nonmetal
Glass 0.01
Cement 0.011
Cement mortar 0.013
Concrete culvert 0.013
Concrete lined channel/pipe 0.015
Wood 0.012
Clay 0.013
Brickwork 0,013
Brickwork with cement mortar 0.015
Masonry/ rubble masonry 0.025
Sanitary sewer coated with slime 0.013
Asphalt 0.013
Plastic 0.013
PVC 0.009-0,011
Polyethylene 0009-0.015
Excavated or Dredged Channel
Straight and clean 0.022
Winding and sluggish 0.025
Dredged 0.028
Rock cut/stony 0.035
Earth bottom, rubble sides 0.03
Unmaintained/uncut brush 0.08
Natural streams
On plain, clean, straight, no pools 0.03
On plain, clean, winding, some pools 0.04
On plain, sluggish, weedy, deep pools 0.07
On mountain, few boulders 0,04
On mountain, large boulders 0.05
a For overland flow roughness coefficient see Table 16.7.
Note: Judgment must be used to determine n for channel characteristics that fall in between these cate- gories. See Chow (1959) for a detailed reference.
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