← MES Jr. Grade
Past Questions — 2020
The flow in a channel is at critical depth. If at a section B a small hump of height DZ is built on the bed of the channel, the flow will be :-
A)
Critical at B
B)
Critical upstream of B
C)
Supercritical at B
D)
Supercritical upstream of B
For a given discharge in an open channel, if the flow is already at critical depth, the specific energy is minimum. When a small hump is introduced at section B, the bed level rises and the available specific energy at that section reduces further. In a critical flow, even a small obstruction makes the flow adjust so that the depth at the hump remains critical (or becomes critically controlled there). Hence the flow at B is critical. The other options are incorrect because sub/supercritical transitions depend on whether the flow is above or below critical depth; here the key condition is that the flow is already critical and the hump produces critical control at B rather than making the flow supercritical upstream or at B.
For the sake of convenience, the characteristic curves of hydraulic turbines are plotted in terms of :-
A)
Theoretical quantities
B)
Actual tests quantities
C)
Unit quantities
D)
Statistical data quantities
Characteristic curves of hydraulic turbines are commonly plotted in terms of unit quantities such as unit discharge, unit speed, and unit power. This makes it possible to compare turbine performance under different heads on a common basis. The other options are incorrect because characteristic curves are not generally based on theoretical quantities, raw actual test quantities, or statistical data quantities.
A sandy clay unit in the earth formation is an example of :-
A)
Aquifuge
B)
Aquiclude
C)
Aquitard
D)
Aquifer
A sandy clay unit is a low-permeability formation that can store water but allows only slow movement of groundwater. Such a semi-pervious layer is called an aquitard. An aquifer, in contrast, is highly permeable and yields water readily. An aquiclude is practically impermeable but may still be porous, while an aquifuge is both non-porous and impermeable.
The difference between a storage weir and a dam is only in :-
A)
height
B)
duration for storage of supply
C)
both (a) & (b)
D)
there is no difference
A weir and a dam are both barriers across a river, but the common distinguishing feature is height. A weir is generally a low overflow structure, while a dam is a higher barrier intended to impound water. The duration of storage is not the defining difference. Hence, the difference between a storage weir and a dam is only in height.
A fluid flow in an elementary rectangular parallelopipe with side length equal to dx, dy and dz is having velocity component in x,y,z directions u,v and w respectively and the mass density of fluid is r. If the fluid is incompressible, the continuity equation in cartesian coordinate is given by :-
A)
¶u/¶x + ¶v/¶y + ¶w/¶z = 0
B)
¶(ru) /¶x + ¶(rv) /¶y + ¶(rw) /¶z = 0
C)
¶r/¶t + ¶(ru) /¶x + ¶(rv) /¶y + ¶(rw) /¶z = 0
D)
¶r/¶t + ¶(ru) /¶x + ¶(rv) /¶y + ¶(rw) /¶z - (¶u/¶x + ¶v/¶y + ¶w/¶z) = 0
For an incompressible fluid, density remains constant, so the continuity equation in Cartesian coordinates reduces to the zero divergence condition: ∂u/∂x + ∂v/∂y + ∂w/∂z = 0. Option (b) is the general continuity form for steady flow of variable density only if time variation is absent, while (c) is the full unsteady compressible continuity equation. Option (d) is not a standard continuity equation.
The Groyne in River Engineering which is constructed in such a way that it points downstream the direction of normal flow is :-
A)
Repelling Groyne
B)
Neutral Groyne
C)
Deflecting Groyne
D)
Attracting Groyne
In river engineering, groynes are classified by the angle they make with the normal flow. A groyne that points downstream in the direction of flow is called a **repelling groyne**. It repels the current away from the bank to reduce erosion. A **neutral groyne** is perpendicular to the bank, while a **deflecting groyne** usually points upstream to deflect flow toward the center of the river. Hence, the correct answer is **Repelling Groyne**.
The method used for testing the consistency of rainfall record is :-
A)
Hyetograph
B)
Mass Curve of rainfall
C)
Thiessen-mean method
D)
Double-mass curve
The consistency of rainfall records is tested using the Double-mass curve method. It compares cumulative rainfall at the station under study with cumulative average rainfall of surrounding stations; any change in slope indicates inconsistency in the record.
Why others are incorrect:
- (a) Hyetograph: shows rainfall intensity over time, not record consistency.
- (b) Mass Curve of rainfall: shows cumulative rainfall vs time, mainly used in hydrology studies, not for consistency testing.
- (c) Thiessen-mean method: used to compute average areal rainfall from station data.
- (d) Double-mass curve: correct method for checking rainfall record consistency.
The table shows extract of computation for daily flow duration curve of typical river for a particular year. Flow Rate (Cumec) 28.00: Days equalled or exceeded 303; Flow Rate (Cumec) 30.00: Days equalled or exceeded ?. Fill-up the Days equalled or exceeded for the flow rate of 30.00 :-
A)
21
B)
4
C)
321
D)
294
In a flow duration curve, a higher flow rate is equalled or exceeded for fewer days. Since 28.00 cumec is equalled or exceeded for 303 days, the nearby higher flow of 30.00 cumec must have a smaller exceedance count. From the given options, the correct extracted value is 4 days. The larger options 294 and 321 are not possible because they would imply almost the same or more days than 28 cumec, which contradicts the definition of a flow duration curve.
The minimum radius of curve recommended in irrigation channel of capacity 3 to 15 cumecs is :-
A)
100 m
B)
159 m
C)
300 m
D)
600 m
In canal design, the recommended minimum radius of curvature increases with canal discharge. For irrigation channels with capacity in the range of 3 to 15 cumecs, the standard recommended minimum radius is about 159 m. Hence option (b) is correct. The other values correspond to different canal sizes or are not the recommended minimum for this discharge range.
For one dimensional flow without recharge in an unconfined aquifer between two water bodies, the steady water table profile is :-
A)
an ellipse
B)
a parabola
C)
a straight line
D)
an arc of a circle
For one-dimensional steady groundwater flow in an unconfined aquifer without recharge, the Dupuit equation gives a water table profile whose head varies as a quadratic function of distance. Therefore the steady water table curve between two water bodies is a parabola. It is not a straight line because the saturated thickness changes along the flow path, and it is not an ellipse or a circular arc.
The flow in the boundary layer along a long thin plate, upto a certain portion of the plate from the leading edge, exhibits the characteristics of :-
A)
Turbulent if the incoming stream is turbulent
B)
Laminar flow if the incoming stream is laminar
C)
Turbulent irrespective of whether the incoming stream is laminar or turbulent
D)
Laminar irrespective of whether the incoming stream is laminar or turbulent
For flow over a long thin plate, the boundary layer starts at the leading edge and, over the initial portion of the plate, it follows the nature of the approaching free stream. If the incoming stream is laminar, the boundary layer begins as laminar. If the free stream is turbulent, disturbance levels are higher and the boundary layer can become turbulent earlier. Hence, the correct choice is that the flow exhibits laminar behavior if the incoming stream is laminar. Options (c) and (d) are too absolute, and (a) is not generally true for the initial boundary-layer development.
The specific speed of turbines having the same efficiency is affected by :-
A)
Sizes of the actual turbine & specific turbine
B)
Certain critical dimensions of actual turbine & specific turbine
C)
Geometrical shape of actual turbine & specific turbine
D)
Both (a) & (b)
Specific speed is a dimensionless parameter used to compare turbines of different sizes but similar performance. For turbines having the same efficiency, the specific speed depends on similarity conditions, especially the geometrical shape of the actual turbine and the corresponding specific (model) turbine. Size alone is not the controlling factor. Hence, option (c) is correct.
The phenomenon in Cast-iron pipe when it becomes numerous and large that interference with the water flow and loss of pressure, making expensive cleaning operations necessary is :-
A)
Corrosion
B)
Tuberculation
C)
Cavitation
D)
Water hammering
In cast-iron pipes, internal corrosion products can form many rough, nodular deposits called tubercles. When these become numerous and large, they obstruct flow and reduce pressure, often requiring expensive cleaning. This phenomenon is called tuberculation. Corrosion is the general chemical deterioration process, cavitation is due to vapor bubble formation and collapse, and water hammering is a pressure surge caused by sudden change in flow.
Choose the correct statement from the followings pertaining to flow of fluid
A)
Velocity potential increases with an increase in velocity in the x.y and z directions
B)
Velocity potential decreases with a decrease in velocity in the x.y and z directions
C)
Flow is always in the direction of increasing velocity potential
D)
Flow is always in the direction of decreasing velocity potential
In potential flow, the velocity components are given by u = dφ/dx, v = dφ/dy, w = dφ/dz, where φ is the velocity potential. Hence the fluid velocity vector points in the direction in which φ decreases most rapidly, so flow occurs from higher velocity potential to lower velocity potential. Therefore, the correct statement is that flow is always in the direction of decreasing velocity potential. Options (a) and (b) are not generally correct statements, and (c) is the opposite of the true relation.
Garret’s diagram for graphical method of designing channel dimensions is based on :-
A)
Lacey’s theory
B)
Kennedy’s theory
C)
Einstein’s equation of probability law
D)
Stage discharge curve
Garret’s diagram is a graphical method used in channel design based on Lacey’s regime theory. Lacey’s theory provides the empirical relations for stable alluvial channels, and Garrett’s diagram is derived from those regime concepts. Kennedy’s theory is based on critical velocity and is not the basis of Garrett’s diagram. Einstein’s equation of probability law relates to sediment transport, and a stage-discharge curve is only a hydraulic rating relation, not the basis of this design diagram.
If the water power required of a pump is 16 kw and the efficiency of the pump is 80%, the pump input power will be :-
A)
12.8 kw
B)
20 kw
C)
20.8 kw
D)
30 kw
Pump efficiency = useful water power / input power. Given water power required = 16 kW and efficiency = 80% = 0.8. So, input power = 16 / 0.8 = 20 kW. Hence the correct option is (b). Option (a) is less than the output power, so it cannot be the input power.
In water treatment operation, a slow mixing process in which destabilized colloidal particles are brought into intimate contact in order to promote their agglomeration is :-
A)
Mixing
B)
Coagulation
C)
Flocculation
D)
Stabilization
In water treatment, after particles are destabilized by coagulation, a slow mixing process is used to bring the particles into close contact so they can form larger agglomerates called flocs. This process is called flocculation. Mixing is only the general blending of water and chemicals, coagulation is the destabilization step, and stabilization is the opposite of particle aggregation.
In Hardy Cross method of pipe network analysis, the correction to be applied to the assumed flows of the circuit for the pipes common to two circuits or loops will be applied :-
A)
Only for one of the loops
B)
for both the loops
C)
not necessary to be applied
D)
for the loop with flow in clock-wise direction
In the Hardy Cross method, when two loops share a common pipe, the flow correction for that common pipe is affected by the correction calculated for each loop. Therefore, the correction must be considered in both loops to satisfy continuity and energy balance simultaneously. Hence, the correct choice is that it is applied for both the loops. The other options are incorrect because applying it only to one loop or not applying it would leave the shared pipe uncorrected in the adjacent loop, and clockwise direction is not the criterion for deciding this.
The Muskingum method of flood routing is a :-
A)
form of reservoir routing method
B)
hydraulic routing method
C)
complete numerical solution of St Venant equations
D)
hydrologic channel routing method
The Muskingum method is a **hydrologic channel routing** method used to route flood waves through river channels using the continuity equation with a storage relationship. It is not a reservoir routing method, and it does not solve the full St. Venant equations. Hydraulic routing methods are more detailed and based on the full flow equations, whereas Muskingum is a simplified hydrologic approach. Hence, option (d) is correct.
As the water flows in irrigation operation, the Duty of water :-
A)
remain same
B)
decreases
C)
increases
D)
either decreases or increases
Duty of water is the area irrigated by a unit quantity of water during the base period. As water flows through canals and distribution channels in irrigation systems, some water is lost by seepage, evaporation, and other losses. Therefore, to irrigate a larger area with the remaining water, the duty of water increases as the water flows in the irrigation operation. Hence, the correct answer is 'increases'.
Choose the correct answer from the followings in connection with Uniform Flow in an open channels:-
A)
Flow properties such as the depth or discharge at a section do not change with time.
B)
Flow properties such as the depth or discharge remain constant along the length of the channel.
C)
Uniform flow practically, can either be steady or un-steady.
D)
Flow in a given channel geometry with only one degree of freedom will always be uniform flow.
Uniform flow in an open channel means that the flow parameters do not change from section to section along the channel length. So depth, velocity, discharge, and flow area remain constant with distance. Option (a) describes steady flow, where properties do not change with time, not necessarily uniform flow. Option (c) is wrong because uniform flow is generally steady in practice, not unsteady. Option (d) is incorrect because having one degree of freedom in channel geometry does not guarantee uniform flow.
Choose the wrong statement from the following in connection with Bligh’s creep theory :-
A)
the outer edges of faces of end sheet piles are much more effective than the inner ones
B)
There is no explanation about the requirements of exit gradient
C)
The theory holds good as long as the horizontal distance between the pile lines is greater than twice their depths
D)
There is no distinction between horizontal and vertical creep
Bligh’s creep theory assumes that seepage follows the contact surface and gives equal weight to horizontal and vertical creep; it also does not properly explain exit gradient. The statement about horizontal distance between pile lines being greater than twice their depths belongs to Lane’s weighted creep concept, not Bligh’s theory. Therefore, option (c) is the wrong statement. Options (a), (b), and (d) are consistent with Bligh’s creep theory.
Slipper bearing in lubrication mechanics is an example of :-
A)
Laminar flow between two fixed plates
B)
Couette flow
C)
A curved surface lubricant film
D)
Dash-Pot mechanism
A slipper bearing (shoe bearing) works with a thin lubricant film between a curved moving surface and a stationary surface, so it is an example of lubrication over a curved surface. It is not flow between two fixed plates, and it is not the standard Couette flow case of parallel plates. A dash-pot is a damping device, not a bearing lubrication model.
Choose the wrong statement from the following in connection with waterlogging in irrigation engineering-
A)
Drainage becomes impossible and CO2 cannot be dissolved
B)
The roots of the plants are confined to the top layers soil above the water-Table
C)
Soil remains warm thus bacterial action becomes sluggish
D)
There is accumulation of alkali salts in the surface soil
Waterlogging means the soil becomes saturated with water and air circulation in the root zone is poor. Because of this, drainage is hampered, carbon dioxide accumulates, and roots remain confined to the upper soil layers above the water table. It also often leads to accumulation of harmful salts in the surface soil. However, the statement that the soil remains warm and therefore bacterial action becomes sluggish is wrong; in waterlogged soil, poor aeration and often lower soil temperature generally reduce microbial activity.
In one complete revolution of the crank in double acting pump, there will be :-
A)
One suction and one delivery stroke
B)
Two suction strokes and one delivery stroke
C)
Two suction strokes and two delivery strokes
D)
One suction stroke and two delivery strokes
In a double-acting pump, water is delivered on both sides of the piston. So, during one complete revolution of the crank, the pump performs two suction strokes and two delivery strokes. Option (a) is for a single-acting pump, not a double-acting pump.