← MES Jr. Grade
Past Questions — 2020
Consider the statement, “ The Hydrograph is the response of a given catchment to a rainfall input. It consists of flow in all the three phases of runoff, viz, surface runoff, interflow and baseflow and embodies the integrated effects of a wide variety of catchment and rainfall parameters having complex interaction”. Choose the correct statement(s) from the followings :-
A)
identical storms in two catchments produce different hydrographs
B)
identical storm in two catchment produce identical hydrographs
C)
two different storms in a given catchment produce identical hydrographs
D)
both (b) & (c) are correct
A hydrograph depends not only on the storm, but also on catchment characteristics such as size, shape, slope, soil type, land use, and drainage. Therefore, even if two catchments receive identical storms, their hydrographs will generally be different. Option (b) is incorrect because different catchments do not respond identically to the same rainfall. Option (c) is also incorrect because two different storms in the same catchment usually produce different hydrographs. Hence, only (a) is correct.
The growth of a community with limited land area for future expansion might be modelled using the :-
A)
Declining growth model
B)
Geometric model
C)
Uniform percentage growth model
D)
Arithmetic constant growth rate model
A community with limited land area cannot grow indefinitely at an increasing percentage rate. When space and resources are constrained, growth tends to become linear, i.e., it increases by a constant amount each period. This is represented by the arithmetic constant growth rate model. The geometric and uniform percentage growth models imply exponential-type growth, which is unsuitable for limited land expansion, while the declining growth model describes slowing growth rather than the basic model for limited-area community growth.
The detention type of Dam among the followings is :-
A)
Spillway
B)
Dike
C)
Weir
D)
Barrage
A detention type dam is meant to temporarily store flood water and release it later in a controlled manner. Among the given options, a dike serves as a detention structure. A spillway is an outlet for excess water, a weir is generally used to raise water level or measure flow, and a barrage is a low-head diversion structure across a river.
The water hammer phenomenon in pipes is due to :-
A)
destruction of flow momentum
B)
increment of flow momentum
C)
lowering of vapour pressure
D)
increment of vapour pressure
Water hammer occurs when flowing water in a pipe is suddenly brought to rest or its velocity changes abruptly, such as by rapid valve closure. This sudden change destroys the momentum of the moving water and creates a pressure surge. Hence, the phenomenon is due to destruction of flow momentum. The other options are incorrect because water hammer is not caused by an increase in momentum or by changes in vapour pressure.
The shear stress in a steady laminar flow through circular pipes (Hagen-poiseuille Law) is given as t = - ¶r /¶x(r/2), the equation indicates :-
A)
Shear stress is zero at the centre of the pipe
B)
Shear stress is maximum at the centre of the pipe
C)
Fluid pressure increases in the direction of flow
D)
Shear stress is constant along the radius of the pipe
For laminar flow in a circular pipe, the shear stress varies linearly with radius: τ = -(r/2)(dp/dx). Since τ is directly proportional to r, at the centre of the pipe where r = 0, the shear stress becomes zero. It increases toward the wall and is maximum at the pipe wall. Hence (a) is correct. (b) is wrong because maximum shear stress occurs at the wall, not the centre. (c) is wrong because pressure decreases in the direction of flow. (d) is wrong because shear stress is not constant; it varies with radius.
The storm Hydrograph is basically to examine the :-
A)
long-term runoff
B)
short-term runoff
C)
Hydrological Drought management
D)
Evapo-transpiration
A storm hydrograph shows the variation of stream discharge during and after a storm event, so it is used to study the catchment response to a single rainfall event. Therefore, it basically examines short-term runoff. Long-term runoff is studied using flow records over extended periods, while drought management and evapo-transpiration are not the primary purpose of a storm hydrograph.
Hydraulic Ram works on the principle of :-
A)
Pascal’s Law
B)
Water hammer
C)
Energy utilization of liquid at low pressure
D)
Centrifugal pump action
A hydraulic ram pump works on the principle of the water hammer effect. When flowing water is suddenly stopped by a valve, its momentum creates a pressure surge that forces a small portion of water to a higher level. Pascal’s law is a general fluid pressure principle, but the specific operating principle here is water hammer. Centrifugal pump action does not apply, and option (c) is too vague and not the defining principle.
The idea of Shock losses in silting phenomenon of channel was introduced by :-
A)
Lacey
B)
Kennedy
C)
Lindley
D)
Meyer Peter
The concept of **shock losses** in the silting phenomenon of canals/channels is associated with **Lindley**. Lindley studied silt movement and related losses in channel flow, and the term is used in the context of channel silting behavior.
Why not the others?
- **Lacey**: known for the regime theory of stable canals, not for introducing shock losses.
- **Kennedy**: known for the critical velocity theory.
- **Meyer-Peter**: known for sediment transport and bed-load movement in rivers, not this concept.
So the correct answer is **(c) Lindley**.
Choose the correct answer from the following for Reaction type hydraulic turbines :-
A)
The water action on the wheel vanes is under pressure greater than atmospheric
B)
The wheel passages are not completely filled with water
C)
The water is supplied at a few points at the periphery of the wheel
D)
Energy applied to the wheel is wholly kinetic energy
Reaction turbines work with water under pressure, so the water acts on the runner vanes while still under pressure greater than atmospheric. In these turbines, the wheel passages are completely filled with water, unlike impulse turbines. Also, water is not supplied only at a few points at the periphery, and the energy transferred is not wholly kinetic energy; it includes both pressure energy and kinetic energy. Therefore, option (a) is correct.
Water treatment method which had been used occasionally alone but usually not incorporated in the modern treatment works anymore is :-
A)
Aeration
B)
Chemical coagulation
C)
Plain sedimentation
D)
Distillation
Plain sedimentation is an old water treatment method that was used occasionally by itself in the past, but it is usually not used alone in modern treatment works. Today it is generally combined with other processes such as coagulation, flocculation, and filtration. Aeration, chemical coagulation, and distillation are all still used in specific water treatment situations, so they are not the best fit.
In a canal regulation works when a distributing channel takes off from the parent channel, the best alignment of an off-take when it makes an angle with the parent channel of :-
A)
Zero angle
B)
Acute angle
C)
Obtuse angle
D)
Right angle
In canal regulation and canal design, an off-taking or distributing channel should generally take off from the parent channel at an acute angle. This helps in smooth flow transition, reduces disturbance and eddy formation, and makes the distribution of water more efficient. A right angle or obtuse angle would cause greater loss of energy and more hydraulic disturbance. Zero angle is not a practical off-take alignment.
A small channel which ultimately feeds the water to irrigation field is :-
A)
Branch canal
B)
Water course
C)
Minors distributary
D)
Major distributary
In canal irrigation, the smallest channel that directly carries water from the distributary to the individual fields is called a water course. A branch canal, minor distributary, and major distributary are all larger canal channels used for distribution before the water reaches the field. Therefore, the correct answer is Water course.
In Siphon mechanism of flow through pipes, arrangement required to be considered to limit the reduction of pressure at the summit is :-
A)
limiting the length of outlet leg
B)
limiting the length of inlet leg
C)
limiting the water pressure at higher elevation reservoir
D)
limiting the water pressure at lower elevation reservoir
In a siphon, the pressure at the summit is minimum because the fluid must rise to the highest point. To avoid pressure dropping excessively (and to prevent cavitation or breaking of the siphon), the discharge side should not be made too long. A longer outlet leg increases head losses and can lower the pressure at the summit further. Hence, limiting the length of the outlet leg is the required arrangement. The inlet leg length is not the main control for summit pressure, and the reservoir pressure is usually atmospheric in both cases.
A gallery in a Gravity dam is :-
A)
a platform as part of the working platform during operation
B)
an arrangement at convenient locations to check visually the water level of dam
C)
An opening left in the Dam running either transversely or longitudinally
D)
a platform for sightseeing by the public
In a gravity dam, a gallery is a passage or opening provided within the dam body, usually running longitudinally or transversely. It is used for inspection, drainage, grouting, and maintenance. Option (a) refers to a working platform, (b) describes a gauge arrangement for water level observation, and (d) is unrelated to dam engineering.
If ew and ea are the saturated vapour pressures of the water surface and air respectively, the Dalton’s law for evaporation E in unit time is given by E = :-
A)
(ew - ea) / L
B)
Ke ew / L
C)
K(ew - ea) / L
D)
K (ew + ea) / L
Dalton’s law states that evaporation is proportional to the vapour pressure deficit, i.e., the difference between saturated vapour pressure at the water surface (ew) and the actual vapour pressure of air (ea). Hence, E = K(ew - ea)/L, where K is a proportionality constant and L represents latent heat-related factor as used in the given form. Option (a) omits the proportionality constant K, option (b) ignores the air vapour pressure term ea, and option (d) wrongly adds the two pressures instead of taking their difference.
A special type of spillway designed in India by Ganesh Iyer is :-
A)
Volute siphon spillway
B)
Saddle siphon spillway
C)
Conduit spillway
D)
Chute spillway
Ganesh Iyer is known for designing the **saddle siphon spillway** in India. This is a special type of siphon spillway. The other options are general spillway types: volute siphon spillway, conduit spillway, and chute spillway, but the one specifically associated with Ganesh Iyer is the **saddle siphon spillway**.
Which of the following irrigation efficiency takes into account the transit losses :-
A)
Water use efficiency
B)
Water surface efficiency
C)
Water distribution efficiency
D)
Water conveyance efficiency
Transit losses are the losses that occur while water is being carried from the source to the field through canals, pipes, or channels. The irrigation efficiency that specifically accounts for these losses is water conveyance efficiency. Water use efficiency relates to how effectively water applied is used by the crop, water surface efficiency deals with uniformity of water distribution over the field surface, and water distribution efficiency measures how uniformly water is distributed in the root zone.
Under identical conditions, evaporation will be the least from which of the followings :-
A)
Sea water
B)
Fresh river water
C)
Water from ponds
D)
Lake water
Evaporation is least from sea water under identical conditions because dissolved salts reduce the vapour pressure of water, thereby lowering its tendency to evaporate. Fresh river water has no such salt effect, so evaporation is higher. Pond water and lake water are generally closer to fresh water but may contain some impurities; they still evaporate more than sea water.
The velocity distribution for turbulent flow in pipes, using usual notation is given as v=V /log y+c, where C is the constant. This logarithmic velocity distribution is applicable to :-
A)
Regions close to the boundary of pipes
B)
Throughout the Cross Section of pipes
C)
Flow in the central region of the pipe
D)
Regions close to the boundary of hydrodynamically rough surface
The logarithmic velocity distribution is part of the turbulent boundary-layer/near-wall region in pipe flow. It describes how velocity varies with distance from the wall and is valid close to the pipe boundary, not across the whole cross-section. The central/core region of the pipe follows a different behavior. Option (d) is too specific: the log law is associated with the near-wall region in turbulent flow, including rough surfaces, but the standard statement for pipe flow is the region close to the boundary of the pipe.
Priming and Depriming in spillway is associted with :-
A)
Trough spillway
B)
Tunnel spillway
C)
Shaft spillway
D)
Siphon spillway
Priming and depriming are the key operating principles of a siphon spillway. When the water level rises high enough, the siphon action primes automatically and the discharge increases. When the level falls, air enters and the siphon breaks, i.e., depriming occurs. The other spillways listed do not operate on this siphonic action.
Protection against corrosion to water pipes by deposition or adsorbtion of ions on metallic surface is
A)
Galvanic protection
B)
Metallic coating
C)
Cathodic protection
D)
Inhibition
Protection against corrosion by deposition or adsorption of ions on the metallic surface is called inhibition. Inhibitors form a protective film or layer on the metal, reducing contact with the corrosive medium.
Why others are incorrect:
- (a) Galvanic protection: uses a sacrificial anode to protect the pipe.
- (b) Metallic coating: protects by covering the metal with another metal layer.
- (c) Cathodic protection: makes the metal act as a cathode using sacrificial anode or impressed current.
So the correct answer is Inhibition.
For a storm of given duration, which of the following storm will have a larger return period :-
A)
storms of smaller intensity
B)
storms of larger intensity
C)
storms of medium intensity
D)
cannot be predicted
For a fixed storm duration, higher intensity rainfall is rarer and therefore has a larger return period. Return period is inversely related to the probability of occurrence: more severe storms occur less frequently. So among storms of the same duration, the one with larger intensity will have the larger return period. Smaller or medium intensity storms occur more often, hence have smaller return periods.
For an annual flood series arranged in decreasing order of magnitude, the return period for a magnitude listed at position m in a total of N entries is :-
A)
m/N
B)
m/(N+1)
C)
(N+1)/m
D)
N/(m+1)
For an annual flood series arranged in descending order, the Weibull plotting position formula is used: Return period, T = (N+1)/m, where N is the total number of observations and m is the rank in decreasing order. Thus, the largest flood (m = 1) gets return period N+1, the next gets (N+1)/2, and so on. The other options do not match the standard flood-frequency plotting position formula.
The useful life of reservoir ended when capacity is reduced to :-
A)
10% of the design capacity
B)
20% of the design capacity
C)
25% of the design capacity
D)
30% of the design capacity
In reservoir sedimentation studies, the useful life of a reservoir is generally considered ended when the live storage/capacity is reduced to about 20% of the original design capacity. This is the standard MCQ answer used in hydrology and irrigation engineering. Hence, option (b) is correct. The other values (10%, 25%, 30%) are not the commonly accepted threshold for useful life end in this context.
The presence of excess sodium in water for irrigation purpose affect the soil’s :-
A)
Permeability
B)
Electrical conductivity
C)
Acidity concentration
D)
Both (a) & (c)
Excess sodium in irrigation water causes soil dispersion and reduces infiltration, which mainly lowers the soil’s permeability. It does not primarily determine electrical conductivity, and acidity concentration is not the direct effect here. Therefore, the correct answer is permeability.