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Past Questions — 2010
The field capacity of a soil depends upon
A)
capillary tension in soil
B)
porosity of soil
C)
both (a) and (b)
D)
neither (a) nor (b)
Field capacity is defined as the amount of soil moisture or water content held in the soil after excess water has drained away and the rate of infiltration has decreased. It is the upper limit of the available water capacity for plants.
1. Capillary Tension (a): Field capacity is fundamentally governed by the balance between the force of gravity (pulling water down) and the capillary forces (holding water in the soil pores). The strength of capillary tension depends on the size of the pores; smaller pores exert higher capillary tension, allowing the soil to retain more water against gravity.
2. Porosity of Soil (b): Porosity refers to the total volume of void space in the soil. Since water is stored within these pores, the total volume available for water storage (and thus the field capacity) is directly related to the soil's porosity and the distribution of pore sizes (texture).
Because field capacity is a result of how much space is available (porosity) and how strongly the water is held in those spaces (capillary tension), both factors are critical. Therefore, option (c) is the correct choice.
For determination of average precipitation in a catchment, best method is
A)
arithmetical method
B)
isohytel mean method
C)
Theissen polygon method
D)
none of the above
To determine the average precipitation over a catchment area, three primary methods are commonly used:
1. **Arithmetical Mean Method**: This is the simplest method, calculating the average of all rain gauge readings. It is only accurate if the gauges are uniformly distributed and the terrain is flat with no significant variation in rainfall.
2. **Thiessen Polygon Method**: This method assigns a weight to each gauge based on the area it represents. It is more accurate than the arithmetical mean because it accounts for non-uniform distribution of gauges, but it assumes that rainfall varies linearly between stations.
3. **Isohyetal Method**: This method involves drawing lines of equal precipitation (isohyets) on a map. It is considered the most accurate (best) method because it accounts for both the distribution of the rain gauges and the actual topographic variations (orographic effects) of the terrain, which the other two methods ignore.
Since the Isohyetal method incorporates the most spatial information and handles complex terrain most effectively, it is recognized as the best method for determining average precipitation.
Hydraulic grade line (H.G.L.) in pipe flow represents
A)
energy head
B)
pressure head
C)
friction head loss
D)
all the above
In fluid mechanics, the Total Energy Line (T.E.L.) represents the total head of the fluid, which is the sum of the pressure head (P/γ), the velocity head (v²/2g), and the datum/elevation head (z). The Hydraulic Grade Line (H.G.L.) is defined as the line representing the sum of the pressure head and the datum head (HGL = P/γ + z). Therefore, the difference between the T.E.L. and the H.G.L. is the velocity head (v²/2g). While the H.G.L. includes the elevation, in the context of pipe flow analysis, it is primarily used to represent the piezometric head (pressure head relative to a datum). Among the given options, 'pressure head' is the most accurate representation of what the H.G.L. tracks, as it excludes the kinetic energy (velocity head) component of the total energy. Option (a) is incorrect because energy head refers to the T.E.L. Option (c) is incorrect because friction head loss is the slope/drop of the H.G.L. along the pipe, not the line itself.
Manning’s equation is used in open channel to estimate
A)
average velocity
B)
average depth
C)
average slope
D)
average discharge
Manning's equation is an empirical formula used in fluid mechanics and hydraulics to calculate the average flow velocity of water in an open channel. The formula is expressed as: V = (1/n) * R^(2/3) * S^(1/2), where 'V' is the average velocity, 'n' is the Manning roughness coefficient, 'R' is the hydraulic radius (area divided by wetted perimeter), and 'S' is the slope of the energy grade line (usually the bed slope for uniform flow). While the average discharge (Q) can be calculated using this equation by multiplying the velocity by the cross-sectional area (Q = A * V), the equation itself is fundamentally designed to solve for the average velocity. Options b and c are parameters used as inputs to the equation, not the primary value estimated by the formula.
In order to have a continuous flow through a siphon, no portion of the pipe be higher than
A)
10 m
B)
10.33 m
C)
5.5 m
D)
7.6 m
A siphon works on the principle of atmospheric pressure pushing liquid up into the tube. For a continuous flow to occur, the pressure at the highest point (the summit) of the siphon must not drop below the vapor pressure of the liquid. If the pressure drops to the vapor pressure, cavitation occurs, and the liquid column breaks, stopping the flow.
1. The maximum theoretical height a column of water can be supported by atmospheric pressure is calculated using the formula: h = P_atm / (ρ * g).
2. Standard atmospheric pressure (P_atm) is approximately 101,325 Pa (N/m²).
3. The density of water (ρ) is approximately 1000 kg/m³ and acceleration due to gravity (g) is 9.81 m/s².
4. Calculation: h = 101,325 / (1000 * 9.81) ≈ 10.33 meters.
Therefore, no portion of the pipe can be higher than 10.33 m above the free surface of the liquid; otherwise, the vacuum created would cause the water to boil/vaporize at room temperature, breaking the siphon effect.
The main function of sleepers is
A)
to hold rails at correct gauge
B)
to support rails
C)
to distribute load from rails to ballast
D)
all the above
In railway engineering, sleepers (also known as ties) are the transverse supports placed under the rails. Their primary functions are as follows:
1. **Maintaining Gauge (Option a):** Sleepers hold the rails at the correct distance from each other (the gauge), ensuring that the track does not spread under the lateral pressure of the train wheels.
2. **Supporting Rails (Option b):** They provide a firm base to support the rails, preventing them from sagging and maintaining the longitudinal alignment of the track.
3. **Load Distribution (Option c):** The rails transmit the heavy concentrated wheel loads to the sleepers, which then distribute this load over a wider area of the ballast. This prevents the rails from sinking into the formation and protects the subgrade from excessive pressure.
Since all three functions are essential and primary roles of the sleepers, the correct answer is 'all the above'.
Major loss that occurs in pipe flow is given by
A)
Darcy’s equation
B)
Reynolds equation
C)
Euler’s equation
D)
Navier-Stokes equation
In fluid mechanics, head loss in a pipe is categorized into two types: Major Loss and Minor Loss.
1. Major Loss: This is the pressure loss due to friction between the flowing fluid and the pipe wall. It is calculated using the Darcy-Weisbach equation: h_f = (f * L * v^2) / (2 * g * D), where 'f' is the friction factor, 'L' is the length of the pipe, 'v' is the velocity, 'g' is acceleration due to gravity, and 'D' is the diameter. Therefore, Darcy's equation is the correct answer.
2. Why other options are incorrect:
- Reynolds equation (or Reynolds Number): This is used to determine the flow regime (laminar, transitional, or turbulent) based on inertial and viscous forces, not to calculate head loss.
- Euler’s equation: This describes the motion of an inviscid (frictionless) fluid, meaning it specifically ignores the losses that the question is asking about.
- Navier-Stokes equation: These are the fundamental partial differential equations that describe the motion of viscous fluid substances. While they form the basis for deriving flow behavior, they are not the specific 'equation' used to calculate major head loss in practical pipe flow applications.
If R is the radius of a simple curve and φ is the angle of deflection, its tangent length is
A)
R sin(φ/2)
B)
R cot(φ/2)
C)
R tan(φ/2)
D)
R cos(φ/2)
In surveying, for a simple circular curve, the tangent length (T) is the distance from the Point of Curve (PC) to the Point of Intersection (PI).
1. Let R be the radius of the curve.
2. Let φ (phi) be the deflection angle (also known as the intersection angle or external angle).
3. In the triangle formed by the center of the curve (O), the point of intersection (PI), and the point of curve (PC), the angle at the center is equal to the deflection angle φ.
4. The line from the center to the PI bisects the deflection angle, creating a right-angled triangle where the angle at the center is φ/2.
5. Using trigonometry in this right triangle:
tan(φ/2) = Opposite / Adjacent = Tangent Length (T) / Radius (R).
6. Rearranging the formula gives: T = R tan(φ/2).
Therefore, option (c) is the correct mathematical relationship for the tangent length of a simple curve.
Stream gauging is the method of measurement of
A)
rainfall
B)
runoff
C)
discharge
D)
evapotranspiration
Stream gauging is the process of measuring the volume of water flowing through a river channel or stream per unit of time, which is technically defined as 'discharge' (typically measured in cubic meters per second, m³/s, or cubic feet per second, cfs).
Here is why the other options are incorrect:
- a. Rainfall: Measured using rain gauges (pluviometers).
- b. Runoff: While stream gauging is used to determine runoff at a specific point, 'runoff' refers to the total amount of precipitation that reaches the stream. Stream gauging specifically measures the instantaneous or average flow rate (discharge).
- d. Evapotranspiration: Measured using lysimeters or calculated via the Penman-Monteith equation, involving atmospheric and soil data, not stream flow measurements.
The first Indian railway was laid in
A)
1775
B)
1804
C)
1825
D)
1853
The first passenger railway line in India was opened on April 16, 1853. It ran between Bori Bunder (Mumbai) and Thane, covering a distance of approximately 34 kilometers. The train was hauled by three locomotives named Sahib, Sindh, and Sultan.
Analysis of other options:
- 1775: This predates the invention of the steam locomotive (developed by Richard Trevithick in 1804).
- 1804: This is the year the first steam locomotive was successfully run in the UK, not India.
- 1825: This marks the opening of the Stockton and Darlington Railway in England, the first public railway in the world, but not in India.
A well conditioned triangle in a triangulation system is
A)
an isosceles triangle of base angles of 56º14'
B)
an isosceles triangle of base angles of 66º14'
C)
an isosceles triangle of base angles of 76º14'
D)
none of the above
Best well-conditioned triangle has angles as close to 60° as possible, standard is isosceles with base angles 56°14'.
If a spur is constructed at about 60º to 80º inclined upstream, it is called
A)
attracting spur
B)
deflecting spur
C)
repelling spur
D)
permeable spur
In river engineering, spurs (or groynes) are structures constructed from the river bank into the channel to protect the bank from erosion or to redirect the flow. They are classified based on the angle they make with the river bank:
1. **Attracting Spur**: These are inclined downstream (usually 60° to 80° to the bank). They attract the flow towards the bank where the spur is located, which can lead to erosion at the nose of the spur and potentially the bank itself.
2. **Repelling Spur**: These are inclined upstream (usually 60° to 80° to the bank). They deflect the current away from the bank and towards the center of the channel, thereby protecting the bank from erosion. This is the specific case described in the question.
3. **Deflecting Spur**: These are generally constructed perpendicular to the bank (90°). They are used to deflect the flow in a specific direction.
4. **Permeable Spur**: This refers to the material construction (e.g., timber piles) rather than the angle of inclination. Permeable spurs allow some water to pass through, reducing the turbulence at the nose.
Since the question specifies a spur inclined upstream at 60º to 80º, it is a repelling spur.
The earthen embankments constructed parallel to the river banks at suitable distance for flood control are called
A)
flood walls
B)
dikes
C)
levees
D)
both (b) and (c)
Step-by-step reasoning: 1. The question asks for the term used for earthen embankments built parallel to river banks to prevent flooding. 2. Levees are defined as embankments built along the banks of a river to prevent the water from overflowing into the surrounding floodplains. 3. Dikes are similar structures; while often used to reclaim land from the sea or protect low-lying land from flooding, in many hydrological and civil engineering contexts, the terms 'levee' and 'dike' are used interchangeably to describe flood-control embankments. 4. Flood walls (Option a) are different because they are typically vertical structures made of concrete or masonry, not 'earthen embankments'. Therefore, since both levees and dikes refer to earthen embankments used for flood control, option (d) is the most comprehensive and correct answer.
In pipe flow, shear velocity V* is related to friction factor f and average velocity V as
A)
V* = V sqrt(f/8)
B)
V* = V sqrt(f/4)
C)
V* = V sqrt(f/1)
D)
V* = V sqrt(f/2)
1. Definition of Shear Velocity (u* or V*): Shear velocity is defined as the velocity scale associated with the wall shear stress (τ₀) in a pipe flow. The formula is: V* = sqrt(τ₀ / ρ), where τ₀ is the wall shear stress and ρ is the fluid density.
2. Relation to Pressure Drop: For a pipe of diameter D and length L, the wall shear stress is related to the pressure drop (ΔP) by the force balance: τ₀ = (ΔP * D) / (4L).
3. Relation to Friction Factor (f): According to the Darcy-Weisbach equation, the pressure drop is given by ΔP = f * (L/D) * (ρV²/2).
4. Substituting ΔP into the shear stress equation:
τ₀ = [(f * (L/D) * (ρV²/2)) * D] / (4L)
τ₀ = (f * ρV²) / 8
5. Substituting τ₀ back into the shear velocity formula:
V* = sqrt((f * ρV²) / (8 * ρ))
V* = sqrt(fV²/8)
V* = V * sqrt(f/8)
Therefore, the shear velocity V* is equal to the average velocity V multiplied by the square root of (f/8). Option (a) is the correct mathematical derivation.
California Bearing Ratio method of designing flexible pavements is more accurate as it involves
A)
character of the road making materials
B)
characteristics of soil
C)
traffic intensities
D)
none of the above
The California Bearing Ratio (CBR) test is a penetration test used to evaluate the mechanical strength of road subgrades and base course materials. The primary purpose of the CBR method in flexible pavement design is to determine the thickness of the pavement layers required to support a specific load without causing excessive deformation in the underlying soil.
1. Why 'characteristics of soil' is correct: The CBR value is a direct measure of the shear strength and bearing capacity of the subgrade soil. By quantifying how much load the soil can sustain (relative to a standard crushed stone), engineers can design a pavement thickness that distributes the traffic load effectively to avoid soil failure.
2. Why 'character of the road making materials' is incorrect: While CBR can be performed on base/sub-base materials, the 'method of designing' specifically relies on the subgrade's bearing capacity as the critical limiting factor.
3. Why 'traffic intensities' is incorrect: Traffic intensity (expressed as Cumulative Standard Axles or MSA) is a separate input used in conjunction with the CBR value to determine the total thickness, but the CBR test itself does not 'involve' or measure traffic; it measures the soil's physical properties.
Main causes of water logging are
A)
excessive rainfall
B)
inadequate surface drainage
C)
low permeability of soil
D)
all the above
Water logging occurs when the soil becomes saturated with water, causing the water table to rise to a level where it restricts the aeration of plant roots. This can be caused by several factors:
1. **Excessive Rainfall (Option a):** When the amount of precipitation exceeds the soil's infiltration capacity and the rate of evaporation/transpiration, water accumulates on the surface and in the root zone.
2. **Inadequate Surface Drainage (Option b):** If the land is poorly graded or lacks proper drainage channels, water cannot flow away from the fields, leading to stagnation and saturation of the soil profile.
3. **Low Permeability of Soil (Option c):** Soils with high clay content (low hydraulic conductivity) prevent water from percolating downward into deeper aquifers, causing water to remain trapped in the upper soil layers.
Since all three factors contribute significantly to the occurrence of water logging, the correct answer is 'all the above'.
Remote sensing is the science of making inferences about objects from measurements, made at a distance, without coming into physical contact with the object under study, may be of the following types
A)
active remote sensing
B)
passive remote sensing
C)
both (a) and (b)
D)
none of the above
Remote sensing is categorized into two primary types based on the source of the energy used to detect the object:
1. **Passive Remote Sensing**: These sensors detect natural radiation that is emitted or reflected by the object or surrounding areas. The most common source of radiation is sunlight. Examples include traditional photography, radiometers, and multispectral scanners.
2. **Active Remote Sensing**: These sensors provide their own source of energy for illumination. The sensor emits radiation toward the target and then measures the radiation that is reflected back. Examples include RADAR (Radio Detection and Ranging) and LiDAR (Light Detection and Ranging).
Since remote sensing encompasses both the use of naturally occurring energy (passive) and artificially generated energy (active), the correct answer is both (a) and (b).
Global Positioning System (GPS) has become widely used aid to
A)
navigation world wide and a useful tool for map making
B)
land surveying, off shore drilling
C)
pipe and power line survey
D)
navigation to civilian ships and air crafts
E)
all the above
The Global Positioning System (GPS) is a satellite-based radionavigation system that provides geolocation and time information to a GPS receiver anywhere on Earth. Its versatility allows it to be used across various sectors:
1. Navigation and Mapping (Option a): GPS is the primary tool for worldwide navigation and is essential for creating accurate digital and physical maps (GIS).
2. Land Surveying and Offshore Drilling (Option b): In civil engineering and geology, GPS (specifically DGPS or RTK) is used for high-precision land surveying and determining the exact coordinates for offshore oil and gas drilling rigs.
3. Infrastructure Surveying (Option c): GPS is used to map the trajectories of underground pipes and overhead power lines to ensure accurate maintenance and installation.
4. Aviation and Maritime (Option d): Civilian ships and aircraft rely on GPS for route planning, positioning, and safety to avoid collisions and navigate open waters/skies.
Since GPS is fundamentally used in all the scenarios listed in options a, b, c, and d, the correct answer is 'all the above'.
River training works are necessary to
A)
direct the river flow in a desired path
B)
minimize the problems of flood and erosion
C)
control meandering and deposition
D)
all the above
River training works refer to various engineering measures adopted to control and guide the flow of a river.
1. **Directing the river flow (Option a):** Structures like guides banks and spurs are used to ensure the river follows a specific channel path, preventing it from shifting away from bridges or critical infrastructure.
2. **Minimizing flood and erosion (Option b):** By stabilizing the banks (using rip-rap or revetments) and managing the flow velocity, river training works reduce the risk of bank erosion and help manage floodwaters more effectively.
3. **Controlling meandering and deposition (Option c):** Rivers naturally tend to meander (curve) and deposit sediment in certain areas, which can lead to channel blockage or unpredictable course changes. Training works help maintain a stable channel alignment and prevent excessive siltation in critical areas.
Since all three objectives are primary goals of river training, the correct answer is 'all the above'.
Capacity of reservoir is usually determined by
A)
mass curve of rainfall
B)
mass curve of inflow
C)
depth-area duration curve
D)
intensity duration frequency curve
The capacity of a reservoir is determined based on the need to store excess water during periods of high inflow and release it during periods of low inflow to meet a specific demand. The 'Mass Curve of Inflow' (also known as the cumulative inflow curve) is a plot of the cumulative volume of water entering the reservoir over time. By plotting the cumulative demand (cumulative outflow) against the cumulative inflow, the maximum difference between the two curves represents the required storage capacity of the reservoir to ensure that the demand is met even during the driest periods.
Why other options are incorrect:
- (a) Mass curve of rainfall: Rainfall is a component of inflow, but reservoir capacity is based on the actual water reaching the reservoir (inflow), which accounts for runoff coefficients and losses.
- (c) Depth-area duration curve: This is used to determine the relationship between the depth of water in a reservoir and the surface area, which helps in calculating the storage volume for a given depth, but it does not determine the required capacity based on demand.
- (d) Intensity duration frequency (IDF) curve: This is used in urban drainage and storm sewer design to relate rainfall intensity, duration, and return period, not for reservoir storage capacity.
Precipitation that occurs due to conflict between two air masses is called
A)
frontal precipitation
B)
convective precipitation
C)
orographic precipitation
D)
cyclonic precipitation
Precipitation is classified based on the mechanism that causes the air to rise and cool.
1. **Frontal Precipitation (Correct):** This occurs when two air masses of different temperatures and densities (e.g., a warm moist air mass and a cold dry air mass) meet. The warmer, lighter air is forced to rise over the colder, denser air. As the warm air rises, it cools adiabatically, leading to condensation and precipitation. This 'conflict' zone is known as a front.
2. **Convective Precipitation:** This occurs when the sun heats the ground, which in turn heats the air immediately above it. This warm air becomes buoyant and rises vertically in currents, leading to localized, often intense rainfall (common in tropical regions).
3. **Orographic Precipitation:** This occurs when moist air is physically forced to rise over a topographic barrier, such as a mountain range. The air cools as it ascends the windward side, resulting in precipitation.
4. **Cyclonic Precipitation:** While frontal precipitation is a type of cyclonic precipitation (occurring in extratropical cyclones), 'frontal' specifically describes the 'conflict between two air masses' mentioned in the question. Cyclonic precipitation is a broader term referring to precipitation associated with low-pressure systems.
According to Railway Board, diamond crossing should be flatter than
A)
1 in 16
B)
1 in 12
C)
1 in 8.5
D)
1 in 6
In railway engineering, a diamond crossing is a configuration where two tracks cross each other at grade. The 'flatness' of the crossing refers to the angle of the crossing. According to the Indian Railway Board standards, to ensure safety, reduce wear and tear on the rails, and prevent derailments caused by excessive lateral forces, diamond crossings should be flatter than 1 in 8.5. A 'flatter' crossing means a larger ratio (e.g., 1 in 10 is flatter than 1 in 8.5), meaning the angle of intersection is smaller. If the crossing is steeper than 1 in 8.5 (e.g., 1 in 6), the impact forces on the wheel flanges and the rail head increase significantly, leading to rapid deterioration of the track and increased risk of accidents. Therefore, 1 in 8.5 is the standard minimum flatness requirement.
Contour lines overlap in
A)
vertical cliff
B)
steep slope
C)
hill
D)
all (a), (b) and (c)
In contour mapping, contour lines are imaginary lines joining points of equal elevation. The spacing and behavior of these lines indicate the nature of the terrain:
1. **Vertical Cliff**: When a terrain is perfectly vertical, multiple elevation points exist at the same horizontal location. Therefore, the contour lines for different elevations will appear to merge or overlap at that specific point on the map.
2. **Steep Slope**: On a steep slope, contour lines are drawn very close to each other, but they remain distinct and do not overlap.
3. **Hill**: A hill is represented by closed concentric loops. While the lines are close together on the sides, they do not overlap.
4. **Overhanging Cliff**: It is worth noting that if a cliff overhangs, the contour lines actually cross each other, but for a standard vertical cliff, they overlap.
Lacey’s regime equation of velocity for calculating flood discharge in river is
A)
V = 10.8R2/3S1/3
B)
V = 10.8R1/2S1/2
C)
V = 10.8R1/3S2/3
D)
V = 10.8R2/3S1/3 (duplicate)
Lacey's Regime Theory is used to determine the characteristics of a river channel in alluvium. According to Lacey, the average velocity (V) of flow in a regime channel is proportional to the hydraulic radius (R) raised to the power of 2/3 and the bed slope (S) raised to the power of 1/3. The empirical formula is expressed as: V = 10.8 R^(2/3) S^(1/3) (where V is in m/s, R is the hydraulic radius in meters, and S is the bed slope).
Comparing this to the options:
- Option (a) matches the formula V = 10.8 R^(2/3) S^(1/3).
- Option (b) suggests V = 10.8 R^(1/2) S^(1/2), which is incorrect.
- Option (c) suggests V = 10.8 R^(1/3) S^(2/3), which is incorrect.
- Option (d) is a duplicate of option (a).
Falling drops of water becomes sphere due to
A)
adhesion
B)
cohesion
C)
surface tension
D)
viscosity
The phenomenon where falling drops of water assume a spherical shape is primarily due to surface tension. Surface tension is the property of a liquid surface that causes it to behave like a stretched elastic membrane. This occurs because molecules at the surface experience a net inward cohesive force, pulling them toward the bulk of the liquid. Mathematically, for a given volume, a sphere has the minimum surface area. To minimize the total surface energy (potential energy), the liquid naturally assumes a spherical shape.
Why other options are incorrect:
- Adhesion: This is the attraction between molecules of different substances (e.g., water and glass). It does not cause a drop to form a sphere in mid-air.
- Cohesion: While surface tension is caused by cohesive forces between similar molecules, 'surface tension' is the specific physical property/effect that results in the minimization of surface area and the formation of a sphere.
- Viscosity: This is the internal friction or resistance of a fluid to flow. While it affects the rate at which a drop falls or deforms, it does not drive the shape toward a sphere.