List Of Objective Questions On Irrigation Water Resources
1.Infiltration capacity
is a constant factor
changes with time
changes with location
changes with both time and location
ANSWER : s: d
2.For supplying water to rabi crop, kharif crop and sugarcane, the channel is designed for a capacity equal to the greater of the water requirement of
rabi or kharif
rabi and kharif or sugarcane
rabi and sugarcane or kharif and sugarcane
rabi or kharif or sugarcane
ANSWER : : rabi and sugarcane or kharif and sugarcane
3.Unit of runoff in M.K.S. system is
cubic metre/sec
metre/sec
cubic metre
square metre
ANSWER : : cubic metre/sec
4.The ratio of the quantity of water stored in the root zone of the crops to the quantity of water actually delivered in the field is known as
water conveyance efficiency
water application efficiency
water use efficiency
none of the above
ANSWER : : water application efficiency
5.The duty is largest
at the head of water course
on the field
at the head of a main canal
same at all places
ANSWER : : on the field
6.When surface of transpiration is submerged under water, then potential evapotranspiration is
much more than evapotranspiration
much less than evapotranspiration
equal to evapotranspiration
equal to or less than evapotranspi-ration
ANSWER : : much more than evapotranspiration
7.Hydrograph is the graphical representation of
runoff and time
surface runoff and time
ground waterflow and time
rainfall and time
ANSWER : s: a
8.The depth of water required to bring the soil moisture content of a given soil upto its field capacity is called
hygroscopic water
equivalent moisture
soil moisture deficiency
pellicular water
ANSWER : : soil moisture deficiency
9.Which of the following is a non-recording raingauge ?
tipping bucket type raingauge
Simon’s raingauge
Steven’s weighing type raingauge
floating type raingauge
ANSWER : : Simon’s raingauge
10.A 70% index of wetness means
rain excess of 30%
rain deficiency of 30%
rain deficiency of 70%
none of the above
ANSWER : : rain deficiency of 30%
11.Assertion A : To estimate the rainfall over a catchment, the number of raingauges required per unit area is large for hilly areas. Reason R : Rainfall gradient is steep. Select your correct answer according to the coding system given below :
Both A and R are true and R is the correct explanation of A
Both A and R are true but R is not the correct explanation of A
A is true but R is false
A is false but R is true
ANSWER : : Both A and R are true and R is the correct explanation of A
12.With the increase in the quantity of water supplied, the yield of most crops
increases continuously
decreases continuously
increases upto a certain limit and then becomes constant
increases upto a certain limit and then decreases
ANSWER : : increases upto a certain limit and then decreases
13.The value of Sodium Absorption Ratio for high sodium water lies between
0 to 10
10 to 18
18 to 26
26 to 34
ANSWER : : 18 to 26
14.The kor depth for rice is 190 mm and kor period is 14 days. The outlet factor for this will be
637 hectares/m3/sec
837 hectares/m3/sec
972 hectares/m3/sec
1172 hectares/m3/sec
ANSWER : : 637 hectares/m3/sec
15.Infiltration rate is always
more than the infiltration capacity
less than the infiltration capacity
equal to or less than the infiltration capacity
equal to or more than the infiltration capacity
ANSWER : : equal to or less than the infiltration capacity
16.If the intensity of rainfall is more than the infiltration capacity of soil, then the infiltration rate will be
equal to rate of rainfall
equal to infiltration capacity
more than rate of rainfall
more than infiltration capacity
ANSWER : : equal to infiltration capacity
17.Irrigation water having the concentration of Na++ , Ca++ and Mg++ as 20, 3 and 1 Milli equivalent per litre respectively will be classified as
low sodium water
medium sodium water
high sodium water
very high sodium water
ANSWER : : medium sodium water
18.A raingauge should preferably be fixed
near the building
under the tree
in an open space
in a closed space
ANSWER : : in an open space
19.Infiltration is the
movement of water through the soil
absorption of water by soil surface
both (a) and (b)
none of the above
ANSWER : : movement of water through the soil
20.Under the same conditions, which of the following shapes of water surface will give the highest rate of evaporation ?
flat water surface
convex water surface
concave water surface
independent of shape of water surface
ANSWER : : convex water surface
21.Which of the following types of rain gauges is used for measuring rain in remote hilly inaccessible areas ?
tipping bucket type
weighing type
floating type
Simon’s raingauge
ANSWER : : tipping bucket type
22.The “outlet discharge factor” is the duty at the head of
main canal
branch canal
watercourse
distributory
ANSWER : s: c
23.Rate of evaporation from a water surface increases if i) difference of vapour pressure between water and air is increased ii) velocity of wind is decreased iii) concentration of soluble solids in water is decreased The correct answer is
(i) and (ii)
(i) and (iii)
(ii) and (iii)
(i). (ii) and (iii)
ANSWER : : (i) and (iii)
24.The amount of irrigation water required to meet the evapotranspiration needs of the crop during its full growth is called
effective rainfall
consumptive use
consumptive irrigation requirement
net irrigation requirement
ANSWER : : consumptive irrigation requirement
25.The water utilizable by plants is available in soils mainly in the form of
gravity water
capillary water
hydroscopic water
chemical water
ANSWER : : capillary water
26.Optimum depth of kor watering for rice is
135 mm
165 mm
190 mm
215 mm
ANSWER : : 190 mm
27.Cyclonic precipitation is caused by lifting of an air mass due to
pressure difference
temperature difference
natural topographical barriers
all of the above
ANSWER : : pressure difference
28.The forces, which are considered for the analysis of an elementary profile of a gravity dam under empty reservoir condition, are i) Water pressure ii) Self weight iii) Uplift iv) Pressure due to earthquake The correct answer is
Only (ii)
(i), (ii) and (iii)
(i), (ii) and (iv)
(i), (ii), (iii) and (iv)
ANSWER : : Only (ii)
29.The total capacity of a reservoir is 25 million cubic metres and dead storage is 5 million cubic metres. If the average volume of sediment deposition is 0.10 million cubic metre per year, then the usefulness of the reservoir will start reducing after
50 years
150 years
200 years
250 years
ANSWER : : 50 years
30.An artesian aquifer is the one where
water surface under the ground is at atmospheric pressure
water is under pressure between two impervious strata
water table serves as upper surface of zone of saturation
none of the above
ANSWER : s: b
31.If it rains between 2 P.M. and 3 P.M. and the entire basin area just starts contributing water at 3 P.M. to the outlet, then time of concentration will be
15 minutes
20 minutes
30 minutes
60 minutes
ANSWER : : 60 minutes
32.A current meter is used to measure the
velocity of flow of water
depth of flow of water
discharge
none of the above
ANSWER : : velocity of flow of water
33.The uplift pressure on a dam can be controlled by i) constructing cutoff under upstream face ii) constructing drainage channels bet-ween the dam and its foundation iii) by pressure grouting in foundation The corret answer is
only (i)
both (i) and (ii)
both (i) and (iii)
(i), (ii) and (iii)
ANSWER : : (i), (ii) and (iii)
34.For a flood control reservoir, the effective storage is equal to
useful storage – valley storage
useful storage + surcharge storage
useful storage + surcharge storage + valley storage
useful storage + surcharge storage -valley storage
ANSWER : : useful storage + surcharge storage -valley storage
35.The useful storage is the volume of water stored in the reservoir between
minimum pool level and maximum pool level
minimum pool level and normal pool level
normal pool level and maximum pool level
river bed and minimum pool level
ANSWER : : minimum pool level and normal pool level
36.The relation between probability (P) and recurrence interval (T) is given by
PT = 1
PT2 = 1
P/T = 1
P/T2 = 1
ANSWER : : PT = 1
37.Trap efficiency of a reservoir is a function of
capacity/inflow ratio
capacity/outflow ratio
outflow/inflow ratio
none of the above
ANSWER : : capacity/inflow ratio
38.The unit hydrograph of a specified duration can be used to evaluate the hydrograph of storms of
same duration only
same and shorter duration
same and longer duration
any duration
ANSWER : : any duration
39.The unit hydrograph due to a storm may be obtained by dividing the ordinates of the direct runoff hydrograph by
direct runoff volume
period of storm
total rainfall
none of the above
ANSWER : : direct runoff volume
40.The normal annual precipitation at stations X, A, B and C are 700 mm, 1000 mm, 900 mm and 800 mm respectively. If the storm precipitation at three station A, B and C were 100 mm, 90 mm and 80 mm respectively, then the storm precipitation for station X will be
70mm
80mm
90 mm
105 mm
ANSWER : : 70mm
41.The water stored in the reservoir below the minimum pool level is called
useful storage
dead storage
valley storage
surcharge storage
ANSWER : : dead storage
42.If d is the depth of the aquifer through which water is flowing, then the relationship between permeability k and transmissible T is given by
T = kd
T = k/d
T= Vkd
k= VTd
ANSWER : : T = kd
43.Horizontal acceleration due to earthquake results in
hydrodynamic pressure
inertia force into the body of the dam
both (a) and (b)
none of the above
ANSWER : : both (a) and (b)
44.S-hydrograph is used to obtain unit hydrograph of
shorter duration from longer duration
longer duration from shorter duration
both (a) and (b)
none of the above
ANSWER : : both (a) and (b)
45.A multipurpose reservoir is the one which is
designed for one purpose but serves more than one purpose
planned and constructed to serve various purposes
both (a) and (b)
none of the above
ANSWER : : planned and constructed to serve various purposes
46.The area between the isohyets 45 cm and 55 cm is 100 square km and between 55 cm and 65 cm is 150 square km. The average depth of annua! precipitation over the above basin of 250 square km will be
50 cm
55 cm
56 cm
60 cm
ANSWER : : 56 cm
47.A deep well
is always deeper than a shallow well
has more discharge than a shallow well
is weaker structurally than a shallow well
both (a) and (b)
ANSWER : : has more discharge than a shallow well
48.The best unit duration of storm for a unit hydrograph is
1 hour
one-fourth of basin lag
one-half of basin lag
equal to basin lag
ANSWER : : one-fourth of basin lag
49.Dimensions of coefficient of transmissibility are
M�L�T�
rvfL’T”1
M� L2 T1
M’LV
ANSWER : : M� L2 T1
50.The uplift pressure on the face of a drainage gallery in a dam is taken as
hydrostatic pressure at toe
average of hydrostatic pressure at toe and heel
two-third of hydrostatic pressure at toe plus one-third of hydrostatic pressure at heel
none of the above
ANSWER : : two-third of hydrostatic pressure at toe plus one-third of hydrostatic pressure at heel
51.The rainfall on five successive days were measured as 100 mm, 80 mm, 60 mm, 40 mm and 20 mm respectively. If the infiltration index or the storm loss rate for the catchment area is earlier estimated as 50 mm/day, the total surface run off will be
50 mm
60 mm
90 mm
140 mm
ANSWER : : 90 mm
52.When the upstream face of a gravity dam is vertical, then the intensity of water pressure at the water surface and at the base respectively will be
0 and wH212
wH2/2and wH2/3
wH and 0
OandwII
ANSWER : re w is unit weight of water and H is the depth of water.
53.Silt excluders are constructed on the
river bed upstream of head regulator
river bed downstream of head regulator
canal bed upstream of head regulator
canal bed downstream of head regulator
ANSWER : : river bed upstream of head regulator
54.If there are two canals taking off from each flank of a river, then there will be
one divide wall and one undersluice
one divide wall and two undersluices
two divide walls and one undersluice
two divide walls and two undersluices
ANSWER : : two divide walls and two undersluices
55.Seepage through foundation in an earthen dam is controlled by providing
rock toe
horizontal blanket
impervious cut off
chimney drain
ANSWER : : impervious cut off
56.The maximum permissible eccentricity for no tension at the base of a gravity dam is
B/2
B/3
B/4
B/6
ANSWER : : B/6
57.The main function of a divide wall is to
control the silt entry in the canal
prevent river floods from entering the canal
separate the undersluices from weir proper
provide smooth flow at sufficiently low velocity
ANSWER : : separate the undersluices from weir proper
58.For wave action in dams, the maximum height of freeboard is generally taken to be equal to
0.5 hw
0.75 hw
1.25 hw
1.50 hw
ANSWER : re hw is height of wave.
59.The most suitable material for the central impervious core of a zoned embankment type dam is
clay
coarse sand
silty clay
clay mixed with fine sand
ANSWER : : clay mixed with fine sand
60.A divide wall is provided
at right angle to the axis of weir
parallel to the axis of weir and up-stream of it
parallel to the axis of weir and down-stream of it
at an inclination to the axis of weir
ANSWER : : at right angle to the axis of weir
61.Which of the following spillways is least suitable for an earthen dam ?
ogee spillway
chute spillway
side channel spillway
shaft spillway
ANSWER : : ogee spillway
62.When the reservoir is full, the maximum compressive force in a gravity dam is produced
at the toe
at the heel
within the middle third of base
at centre of base
ANSWER : : at the toe
63.The minimum size of stone that will remain at rest in a channel of longitudinal slope S and hydraulic mean depth R is given by
4RS
11 RS
7RS
15 RS
ANSWER : : 11 RS
64.As compared to crest of the normal portion of the weir, the crest of the under sluice portion of weir is kept at
lower level
higher level
same level
any of the above depending on the design
ANSWER : : lower level
65.Generally the weir is aligned at right angles to the direction of the main river current because
it ensures less length of the weir
it gives better discharging capacity
it is economical
all of the above
ANSWER : : all of the above
66.The discharge passing over an ogee spillway is given by
CLH3/2
CHL3/2
CLH5/2
CLH1/2
ANSWER : re, L is effective length of spillway crest and H is the total head over the spillway crest including velocity head.
67.As compared to gravity dams, earthen dams
are costlier
are less susceptible to failure
require sound rock foundations
require less skilled labour
ANSWER : : require less skilled labour
68.For the upstream face of an earthen dam, the most adverse condition for stability of slope is
sudden drawdown
steady seepage
during construction
sloughing of slope
ANSWER : : sudden drawdown
69.Seepage through embankments in an earthen dam is controlled by
drainage filters
relief wells
drain trenches
provision of downstream berms
ANSWER : : drain trenches
70.Presence of tail water in a gravity dam i) increases the principal stress ii) decreases the principal stress iii) increases the shear stress iv) decreases the shear stress The correct answer is
(i) and (iii)
(i)and(iv)
(ii) and (iii)
(ii) and (iv)
ANSWER : s: d
71.The flow of water after spilling over the weir crest in chute spillway and side channel spillway respectively are
at right angle and parallel to weir crest
parallel and at right angle to weir crest
parallel to weir crest in both
at right angle to weir crest in both
ANSWER : : at right angle and parallel to weir crest
72.In a chute spillway, the flow is usually
uniform
subcritical
critical
super critical
ANSWER : : super critical
73.The major resisting force in a gravity dam is
water pressure
wave pressure
self-weight of dam
uplift pressure
ANSWER : : self-weight of dam
74.The ratio of average values of shear stresses produced on the bed and the banks of a channel due to flowing water is
less than 1
equal to 1
greater than 1
equal to zero
ANSWER : : greater than 1
75.In case of non-availability of space due to topography, the most suitable spillway is
straight drop spillway
shaft spillway
chute spillway
ogee spillway
ANSWER : : shaft spillway
76.Coefficient of discharge of an ogee spillway
depends on depth of approach and upstream slope
depends on downstream apron interference and downstream submergence
remains constant
both (a) and (b)
ANSWER : : both (a) and (b)
77.According to Khosla’s theory, the exit gradient in the absence of a downstream cutoff is
0
unity
infinity
very large
ANSWER : : infinity