Civil Engineering - Engineering Hydrology
Exam Duration: 45 Mins Total Questions : 30
A catchment has an area of 150 ha and a runoff/rainfall ratio of 0.40.If due to a 10 cm rainfall over the catchment a stream flow at the catchment outlet lasts for 10 h, the average stream flow in the period is
- (a)
1.33 m3/s
- (b)
16.7 m3/s
- (c)
100 m3/min
- (d)
\(6\times { 10 }^{ 4 }{ m }^{ 3 }/h\)
The total observed runoff volume during a 4h storm with a uniform intesity of 2.8 cm/h is \(25.2\times { 10 }^{ 6 }{ m }^{ 3 }\) from a basin of 280 km2 of area.What is the average infiltration rate for the basin?
- (a)
3.6 nm/h
- (b)
4.8 nm/h
- (c)
5.2 nm/h
- (d)
5.5 nm/h
A storm with 14 cm precipitation produced a direct runoff of 8 cm.The time didtribution of the storm is as shown in the table below.
Time from start(h) | Incremental Rainfall(cm) |
1.0 | 1.0 |
2.0 | 2.0 |
3.0 | 2.8 |
4.0 | 3.3 |
5.0 | 2.5 |
6.0 | 1.8 |
7.0 | 0.6 |
What is the \(\phi \)-value of the storm?
- (a)
0.5 cm/h
- (b)
0.7 cm/h
- (c)
0.8 cm/h
- (d)
0.9 cm/h
Results to obtain infiltration capacity curve in exponential form are tabulated below
Time(h) | 0.25 | 0.50 | 0.75 | 1.00 | 1.25 | 1.50 | 1.75 | 2.00 |
fct(cm/h) | 5.60 | 3.20 | 2.10 | 1.50 | 1.20 | 1.10 | 1.00 | 1.00 |
The equation of curve will be,fct=
- (a)
11.0+1.0e-3.07t
- (b)
1.0+11.0e-3.07t
- (c)
1.0+10.0e-3.07t
- (d)
e-3.07t
A 6 h unit hydrograph of a catchment is triangular in shape with a base width of 64 h and peak discharge of 20 m3/s.If a 0.5 cm rainfall excess occurs in 6 h in that catchment, the resulting surface runoff hydrograph will have
- (a)
a base of 128 h
- (b)
a base of 32 h
- (c)
a peak of 40 m3/s
- (d)
a peak of 10 m3/s
For a catchment with an area of 360 km2 and the equilibrium discharge of S-curve obtained by 4 h unit hydrograph in m3/s is
- (a)
250
- (b)
90
- (c)
\(90\times { 10 }^{ 4 }\)
- (d)
\(250\times { 10 }^{ 4 }\)
A 2 h storm hydrograph has 5 units of direct runoff.The two hours unit hydrograph for this storm can be obtained by dividing the originates of storm hydrograph by
- (a)
2
- (b)
\(\frac { 2 }{ 5 } \)
- (c)
5
- (d)
\(\frac { 5 }{ 2 } \)
A 4 h unit hydrograph of a basin can be approximated as a triangle with a base period of 48 h and peak ordinate of 300 m3/s.What is the area of the catchment basin?
- (a)
7776 km2
- (b)
5184 km2
- (c)
2592 km2
- (d)
1294 km2
The yield of a well depends upon
- (a)
permeability of soil
- (b)
area of aquifer opening into wells
- (c)
actual flow velocity
- (d)
All the above
Water present in the artesian aquifer is usually
- (a)
at subatmospheric pressure
- (b)
at atmospheric pressure
- (c)
at 0.5 times 0 the atmospheric pressure
- (d)
above atmospheric pressure
Specific capacity of a well is the
- (a)
volume of water than can be extracted by the force of gravity from a unit volume of aquifer
- (b)
discharge per unit draw down of the well
- (c)
draw down per unit discharge of the well
- (d)
rate of flow through a unit width and entire thickness of aquifer
The performance of a well is measured by
- (a)
specific capacity
- (b)
specific yield
- (c)
storage coefficient
- (d)
permiability coefficient
In an artesian aquifer, the draw down in two observation wells, located at distances of 100 m and 300 m, were found to be the same after one hour and x hours respectively.The value of x in such a case is
- (a)
\(\frac { 1 }{ 9 } h\)
- (b)
3 h
- (c)
9 h
- (d)
27 h
A flood wave with known inflow hydrograph is routed through a large reservoir.The outflow hydrograph will have
- (a)
attenuated peak with reduced time base
- (b)
attenuated peak with increased time base
- (c)
decrease the time base
- (d)
decrease the peak discharge
The direct runoff hydrograph obtained from a catchment is triangular in shape and has a base period of 80 h.The peak flow rate is 30 m3/s and catchment area is 86.4 km2.The rainfall excess that resulated the above hydrograph is
- (a)
5 cm
- (b)
8 cm
- (c)
10 cm
- (d)
16 cm
During a 6 h storm, the rainfall intensity was 0.8 cm/h on a catchment of area 8.6 km2.The measured runoff volume during this period was 256000 m3.The total rainfall was lost due to infiltration, evaporation and transpiration(in cm/h) is
- (a)
0.80
- (b)
0.304
- (c)
0.496
- (d)
0.696
The average rainfall for a 3 h duration storm is 2.7 cm and the loss rate is 0.3 cm/h. The flood hydrograph has a base flow of 20 m2/s and produces a peak flow of 210 m2 /s. The peak of 3 h unit hydrograph is
- (a)
125.30 m3/s
- (b)
105.50 m3/s
- (c)
77.77 m3/s
- (d)
70.37 m3/s
A catchment consists of 35 % area with runoff coefficient 0.45 with the remaining 65% area with runoff coefficient 0.55. The equivalent runoff coefficient will be
- (a)
0.5005
- (b)
0.515
- (c)
0.50
- (d)
0.450
When 3.68 million m3 of water was pumped out from an unconfined aquifer of 6.2 km 2 aerial extent. The water table was observed to go down by 2.6 m. The specific yield of the aquifer for will be
- (a)
19.5 %
- (b)
12.8 %
- (c)
15.5 %
- (d)
22.8 %
The water table -levels in two observation wells 100 m apart are 90 m and 95 m respectively. If the hydraulic conductivity and porosity of the aquifer are 2.5 m/day and 20 per cent, then the actual velocity of flow in the aquifer will be
- (a)
0.125 m/day
- (b)
0.025 m/day
- (c)
0.625 m/day
- (d)
0.225 m/day
The ordinates of a 2 h unit hydrograph at 1 h intervals starting for t=0 are 0,3,8,6,3,2 and 0 m2/s. Use trapezoidal rule for numerical integration if required
What is the catchment area represented by the unit hydrograph?
- (a)
1.00 km2
- (b)
2.00 km2
- (c)
7.92 km2
- (d)
8.61 km2
1 h triangular unit hydrograph of a watershed has the peak discharge of 60 m3/s at 10 h and time base of 30 h. The Φ- index is 0.4 cm/h and base flow is 15 m3/s
The catchment area of the watershed is
- (a)
3.24 km2
- (b)
32.4 km2
- (c)
324 km2
- (d)
3240 km2
1 h triangular unit hydrograph of a watershed has the peak discharge of 60 m3/s at 10 h and time base of 30 h. The Φ- index is 0.4 cm/h and base flow is 15 m3/s
If there is rainfall of 5.4 cm in 1 h, the ordinate of the flood hydrograph at 15 the hour is
- (a)
225 m3/s
- (b)
240 m3/s
- (c)
249 m3/s
- (d)
258 m3/s
An average rainfall of 16 cm occurs over a catchment during a period of 112 h with uniform intensity.The unit hydrograph (unit depth=1 cm, duration =6 h) of the catchment rises linearly from 0 to 30 cumec in the next 12 h. Φ index of the catchment is known to be 5 cumec
Peak discharge of the resulting direct runoff hydrograph shall be
- (a)
150 cumec
- (b)
225 cumec
- (c)
230 cumec
- (d)
360 cumec
Ordinates of a 1 h unit hydrograph at 1 h intervals, starting from t=0 are 0,2,6,4,2,1 and 0 m3/s
Ordinate of a 3 h unit hydrograph for the catchment at t=3 h is
- (a)
2.0 m3/s
- (b)
3.0 m3/s
- (c)
4.0 m3/s
- (d)
5.0 m3/s
The drainage area of a watershed is 50 km2. The Φ -index is 0.5 cm/h and the base flow at the outlet is 10m3/s. One hour unit hydrograph (unit depth=1 cm) of the watershed is triangular in shape with a time base of 15 h. The peak ordinate occurs at 5 h.
The peak ordinate (in m3/s/cm) of the unit hydrograph is
- (a)
10.00
- (b)
18.52
- (c)
37.03
- (d)
185.20
The drainage area of a watershed is 50 km2. The Φ - index is 0.5 cm/h and the base flow at the outlet is 10m3/s. One hour unit hydrograph (unit depth=1 cm) of the watershed is triangular in shape with a time base of 15 h. The peak ordinate occurs at 5 h.
For a storm of depth of 5.5 cm and duration of 1 h, the peak ordinate (in m3/s) of the hydrograph is
- (a)
55.00
- (b)
82.60
- (c)
92.35
- (d)
102.60
The mass curve of a rainfall of duration 100 min is given below. The catchment had an initial loss of 0.6 cm and a Φ -index of 0.6 cm/h
Time (min) | 0 | 20 | 40 | 60 | 80 | 100 |
Cumulative rainfall (cm) | 0 | 0.5 | 1.2 | 2.6 | 3.3 | 3.5 |
The total surface runoff from the catchment is
- (a)
2.9 cm
- (b)
1.96 cm
- (c)
2.3 cm
- (d)
2.5 cm
The mass curve of a rainfall of duration 100 min is given below. The catchment had an initial loss of 0.6 cm and a Φ -index of 0.6 cm/h
Time (min) | 0 | 20 | 40 | 60 | 80 | 100 |
Cumulative rainfall (cm) | 0 | 0.5 | 1.2 | 2.6 | 3.3 | 3.5 |
If the peak of 2 h unit hydrograph is 60 m3/s, then the peak of DRH will be
- (a)
24 m3/s
- (b)
20.69 m3/s
- (c)
114 m3/s
- (d)
150 m3/s
The peak of flood hydrograph due to a 3 h duration isolated storm in a catchment is 270 m3/s. The total depth of rainfall is 5.9 cm assuming an average infiltration loss of 0.3 cm/h and a constant of this base flow of 20 m3/s
If the area of the catchment is 567 km2. The base width of 3 h unit hydrograph (triangular shape) is
- (a)
36 h
- (b)
63 h
- (c)
12 h
- (d)
24 h