ANSWER SCHEMA OF TEST 2 DAC 21502
1. Rainfall distribution can be defined as:
A) Length of rainfall occurs
B) Rainfall fallen over drainage area
C) Ground is saturated due to previous rain
D) Rainfall amount
2. Water flows from most distant point to outlet can be labeled as:
A) Time to peak
B) Lag time
C) Concentration time
D) Base time
3. Time of concentration can be defined as:
A) Base time, lag time and inflow time
B) Time of stream flow, shallow flow and overland flow
C) Frequency, area and rainfall per unit time
D) Daily pan evaporation, wind movement and air temperature
4. Name two (2) concepts of lumped approach:
A) Input and output
B) Translation and storage
C) Sloped and planar
D) Shape and size
5. Discharge of stream flow can be described as:
A) Gallon / area
B) Gram X velocity
C) Liter / hour
D) Hectare / second
6. Definition of stream gauging is:
A) Measuring velocities up to 4 m/s
B) Known as direct determination
C) Important branch of surface runoff
D) Measuring length of wire until 25 m
7. Identify a stream flow measurement.
A) Area-volume method
B) Hydraulic radius technique
C) Slope area method
D) Hydrometry
8. State two (2) features adopted in area velocity method:
A) Unable accessible and stable reach
B) Site straight and stream cross section is defined
C) Gauging site has backwater effects and stable reach
D) Area of cross section at selected section and few years are
9. Give two (2) activities of Mid-section Method.
A) Sectional gauges and determine stream length
B) Survey markings and current meter
C) Measure depth and average velocity
D) Divide cross-section into subsections and measure air flow
10. Discharge estimation will be more accurate if:
A) More section line markings
B) More subsection used
C) Easy accessible
D) Well-defined
11. Two (2) components of hydrograph can be expressed as:
A) Transpiration and precipitation
B) Interflow and baseflow
C) Groundwater and impermeable
D) Hail and snow
12. Two (2) physical characteristics which affecting hydrograph shape are:
A) Rainfall intensity and rainfall time
B) Precipitation type and precipitation amount
C) Basin shape and drainage area
D) Land and forest
13. Hydrograph characteristics are:
A) Crest, rising slope and descending side
B) Recession limb, rising limb and crest
C) Rising, crest and limb
D) Rising limb, base, recession limb
14. Give a method to separate direct run-off.
A) Fixed Section Method
B) Variable Slope Method
C) Empiric Line Method
D) Intersection with Recession Method
15. Assumption in unit hydrograph can be described as:
A) Best time is depends on effective rainfall duration
B) Rainfall cumulative will occur with constant intensity
C) Rainfall is distributed uniformly (effective rainfall)
D) Watershed is formed from a few sub watersheds with inlet and outlet
16. Give a significance of unit hydrograph.
A) Catchment area
B) Structure design
C) Flow forecasting models
D) Wind records
17. Procedures to estimate unit hydrograph are:
A) Plot hyetograph and plot unit hyetograph
B) Calculate runoff volume and calculate area
C) Separate baseflow and plot hydrograph
D) Straight line and section method
18. Slope-area method can be classified as:
A) Hydraulic structures
B) Direct determination of stream flow
C) Indirect determination of stream flow
D) Velocity determination of stream flow
19. Give an equation which related to slope-area method.
A) Rational Method Equation
B) Manning's Equation
C) Peak Flow Equation
D) Deconvolution Equation
20. Identify two (2) types flow structures for indirect stream flow determination.
A) Catchment and watershed
B) Base weir and rectangular notch
C) Hydraulic radius and channel slope
D) Cross section and flume
21. Refer Table 1, calculate the first trial Φ index (cm/hour) if total runoff is 1.3 cm and total
rainfall is 3.5 cm.
Table 1
Time (hour)
Rainfall Intensity (cm/hour)
1
0.5
2
0.9
3
1.1
4
0.7
5
0.3
A) 2.2 cm/hour
B) 0.37 cm/hour
C) 0.44 cm/hour
D) 22 cm/hour
22. Refer Table 2, calculate the time of rainfall excess (hours) for third trial Φ index (cm/hour)
if total runoff is 1.3 cm.
Table 2
Time (hour)
Rainfall Intensity (cm/hour)
A) 5 hours
B) 4 hours
C) 3 hours
D) 2 hours
1
0.5
2
0.9
3
1.1
4
0.7
5
0.3
23. Refer Table 3, determine the range of Φ index (cm/hour) for the second trial if total rainfall
is 3.5 cm.
Table 3
Time (hour)
Rainfall Intensity (cm/hour)
1
0.5
2
0.9
3
1.1
4
0.7
5
0.3
4
0.7
5
0.3
A) 0.9 < Φ index < 1.1
B) 0.7 < Φ index < 0.9
C) 0.5 < Φ index < 0.7
D) 0.3 < Φ index < 0.5
24. Refer Table 4, derive the PEXCESS (cm) if Φ index is 0.475 cm.
Table 4
Time (hour)
Rainfall Intensity (cm/hour)
1
0.5
2
0.9
3
1.1
A) (0.3 - 0.475)(1) + (0.7 - 0.475)(1) + (1.1 - 0.475)(1) + (0.9 - 0.475)(1) + (0.5 - 0.475)(1)
B) (0.7 - 0.475)(1) + (1.1 - 0.475)(1) + (0.9 - 0.475)(1) + (0.5 - 0.475)(1)
C) (1.1 - 0.475)(1) + (0.9 - 0.475)(1) + (0.5 - 0.475)(1)
D) (0.9 - 0.475)(1) + (0.5 - 0.475)(1)
25. Refer Table 5, calculate the total rainfall (cm) if catchment area is 15 hectare.
Table 5
Time (hour)
Rainfall Intensity (cm/hour)
1
0.5
2
0.9
3
1.1
4
1.5
5
1.3
6
0.9
7
0.7
A) 6.5 cm
B) 7.1 cm
C) 7.3 cm
D) 6.9 cm
26. Refer Table 6, calculate the return period, T for the first rank of data.
Table 6
Rank, m
P (mm) for 5 min
P (mm) for 10 min
A) 10
B) 11
C) 12
D) 13
1
59
77
2
55
75
3
53
71
4
51
65
5
45
59
6
43
57
7
41
55
8
37
51
9
35
47
10
33
43
11
31
41
27. Refer Table 7, calculate intensity value (in/hour) for 45 minutes precipitation.
Table 7
Return Period
20
10
Precipitation (in) of Duration
15 min
30 min
45 min
60 min
0.69
1.09
2.09
3.03
0.61
0.93
1.73
2.91
A) 2.71 in/hour
B) 2.19 in/hour
C) 2.79 in/hour
D) 3.03 in/hour
28. Refer Table 8, determine the descending value for 15 minutes precipitation.
Table 8
Year
2015
2016
2017
2018
2019
Precipitation (mm) of Duration:
5 min 10 min 15 min 20 min
15
31
51
71
17
33
55
73
11
27
59
71
19
35
53
79
13
31
57
77
A) 19 mm, 17 mm, 15 mm, 13 mm, 11 mm
B) 35 mm, 33 mm, 31 mm, 31 mm, 27 mm
C) 79 mm, 77 mm, 73 mm, 71 mm, 71 mm
D) 59 mm, 57 mm, 55 mm, 53 mm, 51 mm
29. Refer Table 9, calculate value precipitation depth (in) for 45 minutes precipitation at 10year frequency.
Table 9
Rank
1
2
3
Precipitation (in) of Duration
15 min 30 min 45 min 60 min
0.69
1.09
2.09
3.03
0.61
0.93
1.73
2.91
0.53
0.85
1.59
2.79
Return Period
12
6
4
A) 0.59 in
B) 1.97 in
C) 1.67 in
D) 2.99 in
30. Refer Table 10, calculate value precipitation depth (in) for 15 minutes at 5-year frequency.
Table 10
Rank
1
2
3
A) 0.65 in
B) 0.97 in
C) 0.56 in
D) 1.61 in
Precipitation (in) of Duration
15 min 30 min 45 min 60 min
0.69
1.09
2.09
3.03
0.61
0.93
1.73
2.91
0.51
0.81
1.59
2.79
Return Period
12
6
4
31. Calculate time of shallow concentration (s) for 775 ft length with 3.9 ft/s of velocity.
A) 3022.5 s
B) 198.7 s
C) 0.005 s
D) 3.3 s
32. Refer Table 11, calculate composite runoff coefficient.
Table 11
Surface Type
Wooded
Grass
Impervious
Total Area
A) 1.451
B) 0.483
C) 0.313
D) 3.191
Area, A (km2)
1.5
13.5
11
26
Runoff Coefficient, C
0.9
0.3
0.25
ƩAXC
AXC
1.35
4.05
2.75
8.15
33. Refer Table 12, calculate hydraulic radius (m).
Table 12
Item
Channel Area
(m2)
Value
55
Wetted
Channel Area
(m2)
25
Channel
Perimeter (m)
27
Wetted
Channel
Perimeter (m)
15
Channel Slope
(%)
0.55
A) 2.037 m
B) 1.667 m
C) 3.667 m
D) 0.925 m
34. Refer Table 13, calculate peak runoff, QP (ft3/s) for a 20-year storm using Rational Method.
Table 13
Item
Value
ƩArea
(acre)
33
A) 66 ft3/s
B) 0.64 ft3/s
C) 16.87 ft3/s
D) 10.73 ft3/s
Areaforested Arearesidential
(acre)
(acre)
25
8
Cforested
0.15
Cresidential Ccomposite
0.3
0.19
I10year
(in/hr)
1.71
I20year
(in/hr)
2.69
35. Refer Table 14, calculate the time of concentration (min).
Table 14
Item
Time base
(min)
Overland
Flow Time
(min)
Value
19
17.9
Time To
Peak (min)
Stream
Flow Time
(min)
Time of
Lag (min)
3.7
3.9
3.85
Shallow
Concentrated
Flow Time
(min)
3.95
A) 26.55 min
B) 25.75 min
C) 40.6 min
D) 52.3 min
36. Refer Table 15, calculate stream velocity (m/s).
Table 15
Item
Value
A) 0.475 m/s
B) 0.021 m/s
C) 0.505 m/s
D) 0.671 m/s
Depthwater
(m)
0.65 0.03
3.3
a
b
Ns
(Rev./s)
0.73
Averagewidth
Revolution
(m)
1.7
73
Time
(s)
100
37. Refer Table 16, calculate discharge (m3/s) at middle segment.
Table 16
Item
Value
W2
(m)
3.1
W3
(m)
3.9
Y2
(m)
5.3
V2
Time
Ns
(m/s)
(s)
0.391 0.77 100
A) 1.55 m3/s
B) 7.25 m3/s
C) 1.95 m3/s
D) 18.55 m3/s
38. Refer Table 17, calculate discharge (m3/s).
Table 17
Item
Value
A) 31708.9 m3/s
B) 2.179 m3/s
C) 1.591 m3/s
D) 5.013 m3/s
Depth
(m)
1.9
Areaaverage
(m2)
4.3
Velocityaverage Widthaverage Revolutions Time
(m/s)
(m)
(s)
0.37
2.3
97
150
39. Refer Table 18, calculate the stream discharge (m3/s)
Table 18
Item
Value
C0
(g/m3)
1.1 X 10-10
C1
(g/m3)
3.3 X 10-3
C2
(g/m3)
5.9 X 10-9
q
(m3/s)
19 X 10-6
A) 0.0033 m3/s
B) 10828996 X 10-6 m3/s
C) 0.00000000579 m3/s
D) 0.0000019 m3/s
40. Refer Table 19, calculate number of days.
Table 19
Area
(km2)
Value 13579
Item
A) 6.71 days
B) 5.37 days
C) 950.53 days
D) 6.41 days
Inflow
(m3/s)
0.77
Outflow
(m3/s)
0.55
Precipitation
(m)
0.07
Natural
basin
0.8
Evaporation
(m)
0.01