All questions of Irrigation Engineering for Civil Engineering (CE) Exam

The most preferred soil for the central impervious core of a zoned embankment type of an earthen dam, is
  • a)
    highly impervious clay
  • b)
    highly pervious gravel
  • c)
    coarse sand
  • d)
    clay mixed with fine sand
Correct answer is option 'D'. Can you explain this answer?

Raksha Nair answered
Preferred Soil for Central Impervious Core of a Zoned Embankment Earthen Dam

The central impervious core of a zoned embankment type of an earthen dam plays a crucial role in preventing seepage and leakage of water through the dam. The most preferred soil for this core is clay mixed with fine sand. Let's understand why.

Properties of Ideal Soil for Impervious Core

The ideal soil for the central impervious core of a zoned embankment earthen dam should have the following properties:

1. High Plasticity: The soil should have high plasticity to prevent any cracks or fissures from forming in the core.

2. Low Permeability: The soil should have low permeability to prevent water from seeping through the core.

3. High Cohesion: The soil should have high cohesion to provide stability to the core.

4. High Compaction: The soil should be able to achieve high compaction to form a dense and stable core.

Why Clay Mixed with Fine Sand is Preferred?

Clay mixed with fine sand is the most preferred soil for the central impervious core of a zoned embankment earthen dam because it possesses all the above properties. Let's understand how:

1. High Plasticity: Clay has high plasticity, which prevents any cracks or fissures from forming in the core. Fine sand helps in reducing the plasticity index of the clay, making it easier to work with.

2. Low Permeability: Clay has low permeability, which prevents water from seeping through the core. Fine sand helps in reducing the hydraulic gradient of the soil, which further reduces the permeability.

3. High Cohesion: Clay has high cohesion, which provides stability to the core. Fine sand helps in increasing the angle of internal friction of the soil, which further enhances the stability.

4. High Compaction: Clay mixed with fine sand can achieve high compaction to form a dense and stable core. The compaction can be achieved through proper moisture content, compaction energy, and compaction method.

Conclusion

In conclusion, clay mixed with fine sand is the most preferred soil for the central impervious core of a zoned embankment earthen dam because it possesses the required properties of high plasticity, low permeability, high cohesion, and high compaction.

Permanent wilting point moisture content for a crop represents the
  • a)
    hygroscopic water
  • b)
    capillary water
  • c)
    field capacity water
  • d)
    water of adhesion
Correct answer is option 'A'. Can you explain this answer?

Sanvi Kapoor answered
Permanent wilting point is the point beyond which the roots of plant cannot access water. It is the hygroscopic water. 
Useful soil moisture for plant growth is capillary water.

The total number of independent equations that form the Lacey's regime theory is
  • a)
    6
  • b)
    10
  • c)
    3
  • d)
    4
Correct answer is option 'C'. Can you explain this answer?

Manasa Bose answered
Lacey collected a large number of data of stable channels in Indo-Ganetic plains. Analyzing the data he gave the following equations of regime channel relating regime velocity Vc, silt factor f, hydraulic radius R, area A, sediment size in mm and bed slope S,

These four equations are the Lacey’s basic regime flow equations.

Hydraulic depth is the ratio of
  • a)
    wetted area to wetted perimeter
  • b)
     
    Area of flow section and top water surface width.
  • c)
    wetted area to bottom width
  • d)
    wetted perimeter to top width
Correct answer is option 'B'. Can you explain this answer?

Prasad Desai answered
Hydraulic Depth in Civil Engineering

Hydraulic depth is a term used in fluid mechanics and civil engineering to describe the ratio of the cross-sectional area of flow to the wetted perimeter. It is an essential parameter for analyzing open channel flow and is used to determine the water surface profile, velocity distribution, and friction losses.

Importance of Hydraulic Depth

Hydraulic depth plays a vital role in analyzing open channel flow as it helps in determining the flow characteristics of water. By calculating the hydraulic depth, engineers can understand the depth of water and the amount of resistance to flow. Some of the key benefits of hydraulic depth include:

- It helps in determining the velocity of water in an open channel.
- It helps in analyzing the resistance of the channel bed and walls to water flow.
- It helps in determining the depth of flow in a channel.

Calculation of Hydraulic Depth

Hydraulic depth is calculated as the ratio of the cross-sectional area of flow to the wetted perimeter. The formula for calculating hydraulic depth is:

Dh = A/P

Where,

Dh = Hydraulic depth
A = Cross-sectional area of flow
P = Wetted perimeter

For a rectangular channel, the formula for calculating hydraulic depth is:

Dh = b*y/(b+2y)

Where,

b = Bottom width of the channel
y = Depth of flow

Conclusion

In conclusion, hydraulic depth is an essential parameter for analyzing open channel flow in civil engineering. It helps in determining the velocity of water, resistance to flow, and depth of flow in a channel. The correct answer to the given question is option 'B,' which states that hydraulic depth is the ratio of the cross-sectional area of flow to the wetted perimeter.

Consider the following statements:
1. In a super-passage, the drain runs over the canal.
2. In a siphon, the drain runs below the canal.
3. In a siphon aqueduct, type-II, the canal banks are made of RCC walls.
Which of these statements are correct?
  • a)
     1 only
  • b)
    1 and 2 only
  • c)
    2 and 3 only
  • d)
    1 and 3 only
Correct answer is option 'D'. Can you explain this answer?

Shraddha Datta answered
A super passage is just like a bridge in which the natural drain is carried over the canal. A super passage is constructed where the bed of the drain is well above the canal F.S.L.
A syphon serves the same purpose as superpassage and is constructed where the F.S.L.

For the upstream slope of an earth dam the most critical condition is
  • a)
    sudden drawdown condition
  • b)
    steady seepage condition
  • c)
    neither sudden drawdown nor steady seepage
  • d)
    during construction when the reservoir is allowed to be filled.
Correct answer is option 'A'. Can you explain this answer?

Critical Condition for Upstream Slope of an Earth Dam

The upstream slope of an earth dam is subjected to various conditions that can affect its stability. Among these conditions, the most critical one is sudden drawdown condition. Let us discuss this in detail.

Sudden Drawdown Condition

Sudden drawdown condition refers to the rapid drainage of water from the reservoir behind the dam. This can happen due to various reasons such as a sudden failure of an outlet gate or an earthquake. When the water level drops suddenly, the soil particles in the upstream slope of the dam get disturbed and lose their cohesion. This can cause the slope to become unstable and lead to slope failure.

Why Sudden Drawdown is Critical?

Sudden drawdown is critical for the upstream slope of an earth dam because of the following reasons:

1. Loss of Cohesion: The soil particles in the upstream slope of the dam are held together by the cohesive forces between them. When the water level drops suddenly, these forces are disturbed, and the soil loses its cohesion. This can cause the slope to become unstable and lead to slope failure.

2. Pore Water Pressure: The water in the soil pores exerts pressure on the soil particles. When the water level drops suddenly, this pressure decreases rapidly, causing the soil particles to rearrange themselves. This can cause the slope to become unstable and lead to slope failure.

3. Shear Strength: The shear strength of the soil depends on the stress conditions and the soil properties. When the water level drops suddenly, the stress conditions change rapidly, causing the shear strength of the soil to decrease. This can cause the slope to become unstable and lead to slope failure.

Conclusion

In conclusion, sudden drawdown condition is the most critical condition for the upstream slope of an earth dam. It can cause the soil particles to lose their cohesion, decrease the pore water pressure, and decrease the shear strength of the soil. This can lead to slope failure and pose a significant risk to the safety of the dam. Therefore, it is essential to consider this condition while designing and constructing an earth dam.

Water-logging of cropped land leads to reduced crop yields, due to
  • a)
    ill-aeration of root zone, causing lack of oxygen to plants
  • b)
    growth of water-loving plants interfering with the sown crop
  • c)
    surrounding of the root zone by the resultant saline water, which extracts the good water from plant roots by osmosis
  • d)
    all of the above
Correct answer is option 'D'. Can you explain this answer?

Ameya Sen answered
The life of a plant depends upon the nutrients like nitrates and the form in which the nitrates are consumed by the plants is produced by the bacteria, under a process called nitrification.
These bacteria need oxygen for their survival. The supply of oxygen gets cutoff when the land becomes ill aerated, resulting in death of these bacteria, and fall in production of plant’s food and consequent reduction in the plant’s growth, which reduces the crop yield.

If the uplift pressure is neglected, the base width of an elementary profile of a gravity dam of height H, having relative' density of the dam material = Sc, and coefficient of friction = μ is
  • a)
    H/(Sc + 1)
  • b)
    H/(Sc - 1)1/2
  • c)
    larger of 
  • d)
    smaller of 
Correct answer is option 'C'. Can you explain this answer?


Hence, if B is taken equal to or greater than  no tension will be developed at the heel 
with full reservoir.
When, C = 1

If uplift is not considered,

For the dam to be safe in sliding,


If C = 0, i.e., no uplift is considered then,

Irrigation frequency is a function of
  • a)
    crop only
  • b)
    soil, crop and climate
  • c)
    soil, crop, climate and fertilizer
  • d)
    soil and climate
Correct answer is option 'B'. Can you explain this answer?

Irrigation frequency is the number of times irrigation is required to be done to maintain the required soil moisture level for a crop to grow and yield optimally. The frequency at which irrigation is required depends on several factors, which are discussed below.

Factors affecting irrigation frequency

Soil characteristics: The texture, structure, and water-holding capacity of the soil determine how much water the soil can retain and how quickly it drains. Sandy soils drain water quickly and require more frequent irrigation, whereas clay soils hold water for a longer time and require less frequent irrigation.

Crop water requirement: Different crops have different water requirements depending on their growth stage. For example, the water requirement of a crop during vegetative growth is higher than during the reproductive phase. The crop water requirement is also influenced by the crop's rooting depth, leaf area, and canopy cover.

Climate: The evapotranspiration rate (ET) of a crop, which is the amount of water lost through evaporation from the soil and transpiration from the plant, is influenced by climate factors such as temperature, humidity, wind speed, and solar radiation. Regions with high temperatures and low humidity require more frequent irrigation.

Fertilizer requirement: The application of fertilizers increases the water requirement of a crop as it increases the crop's growth rate and nutrient uptake. Therefore, the frequency of irrigation should be adjusted to ensure that the soil moisture level is adequate for both crop growth and fertilizer uptake.

Conclusion

In conclusion, irrigation frequency is a function of soil, crop, and climate factors, and should be adjusted based on the specific requirements of each crop. Proper irrigation management can help to optimize crop yield, reduce water use, and increase the sustainability of agricultural practices.

Safety ladders are provided in large irrigation canals, to
  • a)
    enable the fish to pass from one place to another
  • b)
    enable the cattle to cross the canal
  • c)
    enable the swimmers to get out of the canal
  • d)
    provide safe exit to avoid accidental drowning
Correct answer is option 'D'. Can you explain this answer?

Rahul Chauhan answered
In large canals, safety ladders are generally provided on side slopes, at suitable intervals along the canal length. These ladders can be used by persons or cattle, that may be swept away with the flowing water in the canal. Such a person, who may otherwise get drowned, may catch hold of one such ladder and can climb it to get out of the canal easily.

The Garret’s diagrams are based on
  • a)
     Lacey’s theory
  • b)
    Khosla’s theory
  • c)
     Bligh’s theory
  • d)
    Kennedy’s theory
Correct answer is option 'D'. Can you explain this answer?

Rithika Reddy answered
A lot of mathematical calculations are required in designing irrigation channels by the use of Kennedy’s method . To save mathematical calculations, graphical solution of Kennedy’s and Kutter’s equation, was evolved by Garret.

The factor which is not primarily responsible for meander in an alluvial river, is
  • a)
    variation of discharge
  • b)
    excess silt load
  • c)
    deficient silt load
  • d)
    None of these
Correct answer is option 'C'. Can you explain this answer?

Pankaj Kapoor answered
The widely accepted theory behind meandering is based upon the extra turbulence generated by the excess of river sediment during floods. During floods, the river carries tremendous amount of silt charge. When the silt charge is in excess of the quantity required for stability, the river starts building up its slope by depositing the silt on its bed. This accretion is the primary process, which leads to meandering.

The centre of pressure of wave pressure due to wave of height hw acting on a gravity dam will be at a. height above the maximum still water level of
  • a)
    hw/2
  • b)
    3hw/&
  • c)
    hw/3
  • d)
    2hw/3
Correct answer is option 'B'. Can you explain this answer?

The wave pressure acting on the dam due to the wave of height h_w can be calculated using the following formula:
p = 1/2 * ρ * g * h_w * (1 + cos(2πx/L))
Where:
  • p is the wave pressure
  • ρ is the density of water
  • g is the acceleration due to gravity
  • h_w is the wave height
  • x is the horizontal distance from the dam
  • L is the wavelength
The center of pressure of this wave pressure distribution is located at a height of 2/3 * h_w above the maximum still water level.
This is because the wave pressure distribution follows a sinusoidal pattern, and the centroid of this pressure distribution is located at 2/3 of the wave height above the still water level.
Therefore, the correct answer is that the center of pressure of the wave pressure due to a wave of height h_w acting on a gravity dam is located at a height of 2/3 * h_w above the maximum still water level.

Under-drainage arrangements in canals are- necessarily required in
  • a)
    unlined canals
  • b)
    Both (a) and (c)
  • c)
    Lined canal
  • d)
    lined canals constructed on sandy soils alone
Correct answer is option 'B'. Can you explain this answer?

Poulomi Patel answered
Under-Drainage Arrangements in Canals

Introduction:
Canals are constructed to transport water from one place to another for irrigation, industrial use, or other purposes. It is essential to design an efficient drainage system to maintain the structural stability of the canal. Under-drainage arrangements are necessary to ensure the proper functioning of the canal.

Lined Canals:
Lined canals are constructed with a lining material such as concrete, asphalt, or clay to prevent seepage of water from the canal. However, under-drainage arrangements are still required in lined canals to remove the seepage water that penetrates through the lining material. The under-drainage system consists of perforated pipes laid beneath the canal bed, which collects the seepage water and discharges it into a sump or a nearby water body.

Unlined Canals:
Unlined canals are constructed without any lining material, and the water flows through the soil. Under-drainage arrangements are necessary in unlined canals to reduce the seepage losses. The under-drainage system in unlined canals is similar to that of lined canals.

Conclusion:
Under-drainage arrangements are necessary in both lined and unlined canals to maintain the stability of the canal and reduce the seepage losses. Proper design and construction of the under-drainage system are essential for the efficient functioning of the canal.

With the increase in its capacity-inflow ratio, the trap efficiency of a reservoir:
  • a)
    increases
  • b)
    decreases
  • c)
    remains unchanged
  • d)
    may increase or decrease depending on the reservoir characteristics
Correct answer is option 'A'. Can you explain this answer?

The trap efficiency of a reservoir is affected by its capacity-inflow ratio. This ratio is the storage capacity of the reservoir divided by the annual inflow volume. Generally, as the capacity-inflow ratio of a reservoir increases, the trap efficiency also increases. This is because a larger or deeper reservoir has more volume to trap sediments before they can be discharged.
Hence, the correct answer is: increases.

An irrigation outlet is said to be proportional, when its
  • a)
    sensitivity = 1
  • b)
    flexibility = 1
  • c)
    setting = 1
  • d)
    all of the above
Correct answer is option 'B'. Can you explain this answer?

Puja Sharma answered
The outlet is said to be proportional when the rate of change of outlet discharge equals the rate of change of channel discharge.
∴ outlet is, 'proportional' when flexibility’ equals unity.

The river reach upstream of a newly built dam may behave as
  • a)
    aggrading
  • b)
    degrading
  • c)
    virgin
  • d)
    None of these
Correct answer is option 'A'. Can you explain this answer?

Avinash Mehta answered
The correct answer is option 'A', aggrading.
When a dam is built, the flow of water and sediment is impeded, and sediment is deposited in the reservoir area, upstream of the dam. This can result in an increase in the elevation of the river bed and an increase in the width of the channel in the reach upstream of the dam, a process known as aggradation. This process continues until the river reaches a new equilibrium state with the new flow and sediment conditions. The aggradation could lead to an increase of the river bed level and the width of the channel in the reach upstream of the dam and it could be a problem for the dam and the infrastructure around it.

Trap efficiency of a storage reservoir is defined as
  • a)
    Total annual seiment inflow/Reservoir capacity
  • b)
    Total sediment deposited in a given period/Total sediment inflow in that period
  • c)
    Total annual seiment deposited in the reservoir/Dead storage capacity of the reservoir
  • d)
    None of the above
Correct answer is option 'B'. Can you explain this answer?

Gate Funda answered
Trap efficiency of a storage reservoir is the ratio of the total amount of sediment that is trapped or deposited in the reservoir to the total amount of sediment that enters the reservoir. It is a measure of the effectiveness of the reservoir in capturing sediment.
The correct definition of trap efficiency is: Total sediment deposited in a given period / Total sediment inflow in that period

Groynes are adopted for river bank protection works. When it is placed inclined downstream in the direction of flow in the river, it is designated as which one of the following?
  • a)
    Repelling groyne
  • b)
    Attracting groyne
  • c)
    Neither repelling nor attracting groyne
  • d)
    Fixed groyne
Correct answer is option 'B'. Can you explain this answer?

A groyne pointing downstream has the property of attracting the flow towards it and is called an attracting groyne. In attracting groynes scours holes are developed nearer the bank, as compared to those in a repelling groyne. Since such attracting groynes bring the water current as well as scour holes nearer the bank and make it more susceptible to damage, they are not used generally. The groynes are therefore, generally aligned either perpendicular to the bank or pointing upstream (repelling groyne).

The ‘safety valve’ of a dam is its
  • a)
    drainage gallery
  • b)
    inspection gallery
  • c)
    spillway
  • d)
    outlet sluices
Correct answer is option 'C'. Can you explain this answer?

A spillway is a structure constructed at a dam site, for effectively disposing of the surplus water from upstream to downstream. Had there been no such structure, the water level must have exceeded maximum reservoir level, and ultimately would have crossed the freeboard and thus overlapped the dam, causing the failure of the dam. Hence a spillway is essentially a safety valve for a dam.

An attracting groyne is one which is
  • a)
    inclined upstream
  • b)
    inclined downstream
  • c)
    normal to the bank
  • d)
    same as a repelling groyne
Correct answer is option 'B'. Can you explain this answer?

A Groyne painting downstream has the property of attracting the flow towards it and is called an attracting groyne. In attracting groynes scour holes are developed nearer to the bank, as compared to those in a repelling groyne.

The spillway which can be adopted with ease on gravity as well as earthen dams, is
  • a)
    ogee spillway
  • b)
    chute spillway
  • c)
    both ogee as well as chute spillway
  • d)
    Noneofthese
Correct answer is option 'B'. Can you explain this answer?

Gauri Roy answered
An ogee spillway is mostly suitable for concrete gravity dams especially when the spillway is located within the dam body in the same valley. The trough spillway or chute spillway is the simplest type of a spillway which can be easily provided independently and at low costs. It is lighter and adaptable to any type of foundations and hence provided easily on earth and rockfill dams.

Leaching is a process
  • a)
    by which alkali salts present in the soil are dissolved and drained away :
  • b)
    by which alkali salts in soil come up with water
  • c)
    of draining excess water of irrigation
  • d)
    which controls water-logging
Correct answer is option 'A'. Can you explain this answer?

Tanishq Nair answered
Leaching is the process in which land is flooded with adequate depth of water. The alkaii salts' present in soil, get dissolved with this water which percolate down to join the water table or are drained away by sub-surface drains,
Leaching requirement, 
Dd is Depth of water drained out per unit area
Di is Depth of irrigation water applied per unit area

ECi is Electrical conductivity of irrigation water
ECd is Electrical conductivity of drained water.

What type of cross drainage work is provided when the canal runs below the drain, with FSL of canal well below the bed of the drain?
  • a)
    Aqueduct
  • b)
    Super passage
  • c)
    Level crossing
  • d)
    Siphon aqueduct
Correct answer is option 'B'. Can you explain this answer?

If bed level of canal is sufficiently above the HFL of the drain, an aqueduct is the right choice. Sometimes bed level of canal may be little below the HFL of drain so that water flows under syphonic action. This structure is known as aqueduct syphon.If bed level of the drain is sufficiently above the canal FSL, a super passage may be constructed. If the canal FSL is little above bed level of drain to allow syphonic action, the structure is called Canal Syphon. Aqueduct or superpassage type of drainage works are used when high flood discharge is large and continues for a sufficient time.
A level crossing is used when the canal water and drain water are allowed to intermingle with each other. This is adopted when high flood drainage discharge is short lived.

During the construction of an earthen dam by hydraulic fill method, development of pore pressures become important in the
  • a)
    central impervious core
  • b)
    pervious outer shell
  • c)
    both (a) and (b)
  • d)
    None of the above
Correct answer is option 'A'. Can you explain this answer?

Simran Saha answered
In hydraulic -fill method, the dam body is constructed by excavating and transporting soils by using water. Pipes called flumes, are laid along the outer edge of the embankment. Since the fall is saturated when placed, high pore pressure develop in the core material, and the stability of the dam must be checked.

Under which one of the following categories is the river Ganga classified in the reach through UP and Bihar ?
  • a)
    Straight river
  • b)
    Meandering river
  • c)
    Braided river
  • d)
    Deltaic river
Correct answer is option 'B'. Can you explain this answer?

Prerna Menon answered
Formation of successive bends of reverse order in a river may lead to the formation of a complete S curve called meander. Such a river is called meandering river.
When a river flows in two or more channels around alluvial islands, it is known as a braided river.
Deltaic river is a river which gets divided into branches before joining the sea, thus forming a Δ shaped delta.

In an irrigation system, the land was divided into a large number of smaller size unit areas, having fairly level surface, by bunds and cross ridges. The basins thus created were filled with water to the desired depth and the Water was retained for some time. This method of irrigation is known as 
  • a)
    border method
  • b)
    check basin method
  • c)
    sub-irrigation
  • d)
    contour irrigation
Correct answer is option 'B'. Can you explain this answer?

Check flooding is similar to ordinary flooding except that the water is controlled by surrounding the check area with low and flat levels. Levels are generally constructed along the continuous having vertical interval of about 5 to 10 cm. 
This method is suitable for more permeable soils as well as for less permeable soils. The water can also be held on the surface for a longer time in case of less permeable soils.

The rate of change of discharge through an irrigation outlet becomes equal to the rate of change of water depth in the channel, when its.
  • a)
    flexibility is 1
  • b)
    sensitivity is 1
  • c)
    setting is 1
  • d)
    sensitivity is zero
Correct answer is option 'B'. Can you explain this answer?

Tanishq Rane answered
Sensitivity is defined as the ratio of the rate of change of discharge through the outlet to the rate of change of water level of the distributary, referred to the normal depth of the channel.

A fully modular canal outlet has its
  • a)
    sensitivity = 1, and flexibility = 1
  • b)
    sensitivity = 1, and flexibility = 0
  • c)
    sensitivity = 0, and flexibility = 1
  • d)
    sensitivity = 0, and flexibility = 0
Correct answer is option 'D'. Can you explain this answer?

Navya Saha answered
Rigid modules or modular outlets are those through which the discharge is constant and fixed within limits irrespective of the fluctuations of the water levels of either the distributary or of the water course or of both .
∴  sensitivity = 0, and flexibility = 0.

At the foot of a spillway, the jump rating curve is below the tailwater curve at low flows and above it at high flows. The suitable type of energy dissipator for this situation is
  • a)
    a ski-jump bucket
  • b)
    a horizontal apron
  • c)
    a sloping apron
  • d)
    a stilling pool
Correct answer is option 'D'. Can you explain this answer?

Rajeev Menon answered
Definition of stilling basin: 
A depression in a channel or reservoir deep enough to reduce the velocity or turbulence of the flow.

IS code for stilling basin (IS 4997): Criteria for design of hydraulic jump type stilling basins with horizontal and sloping aprons.

How does the energy dissipation occur in stilling basin:

Aprons concrete impact basin is an energy-dissipating device located at the outlet of the spillway in which flow from the discharge conduit strikes a vertical hanging baffle. Energy dissipation occurs as the discharge strikes the baffle, thus, performance is not dependent on the tailwater.

Stilling basin energy dissipator with pool - MLL Concrete

Stilling basin energy dissipator with pooapronsl

Consider the following statements:
1. High water training is undertaken to protect against damage due to floods.
2. Low water training is undertaken to provide sufficient depth for navigation.
3. Mean water training is undertaken to provide efficient disposal of sediment load.
Which of these statements is/are correct?
  • a)
    1 and 2 only
  • b)
    1, 2 and 3
  • c)
    2 and 3 only
  • d)
    2 only
Correct answer is option 'B'. Can you explain this answer?

Lavanya Menon answered
1) High water training works ( training for discharge )
High water training works are constructed for the purpose of quick disposal of maximum flood and to protect adjoining land against damage due to floods.  It aims to provide sufficient river cross-section for stage passage of maximum flood.
2) Low water training works (training for depth)
It is undertaken with the primary purpose of providing sufficient water depth for navigation during a low flow period. Generally, spurs are constructed to contract the width of the channel and hence to increase the depth.
3) Mean water training works ( training for sediments )
It is undertaken with the primary purpose of providing efficient disposal of sediment load and bedload thus preserving the channel in good shape. It is the most important training of the three types.

Lining of irrigation channels
  • a)
    increases water logging
  • b)
    increases channel cross section .
  • c)
    increases command area
  • d)
    increases chances of breaching
Correct answer is option 'C'. Can you explain this answer?

Swati Dasgupta answered
A lined canal can be designed smaller in cross- section and also in length. The steeper gradients can be provided because higher velocities are permissible. It can, therefore, help to bring high areas under command.

Commonly adopted moisture tension, in atmosphere, of a soil at permanent wilting point is
  • a)
    15
  • b)
  • c)
    45
  • d)
    150
Correct answer is option 'A'. Can you explain this answer?

Sravya Tiwari answered
 
The soil moisture tension at the permanent wilting point is usually around 15 atmospheres or -15 bars. This is the point at which plants can no longer extract enough water to meet their needs and remain wilted until water is added to the soil. 

‘Bank storage’ in a dam reservoir:
  • a)
    increases the computed reservoir capacity
  • b)
    decreases the computed reservoir capacity
  • c)
    sometimes increases and sometimes decreases the computed reservoir capacity
  • d)
    has no effect on computed reservoir capacity
Correct answer is option 'A'. Can you explain this answer?

Preethi Datta answered
When the reservoir is filled up, certain amount of water seeps into the permeable reservoir banks. This water comes out as seen as the reservoir gets depleted. This volume of water is known as bank storage. The bank storage efficiently increases the capacity of the reservoir.

The efficiency of water conveyance does not depend upon
  • a)
    method of application of water 
  • b)
    geometry of the conveyance system
  • c)
    nature of the boundary of the conveyance system
  • d)
    climatic conditions
Correct answer is option 'D'. Can you explain this answer?

Srestha Datta answered
Efficiency of Water Conveyance

Efficiency of water conveyance refers to the ability of the conveyance system to deliver water to the desired location without loss or wastage. It is an important aspect of water management and irrigation systems.

Factors Affecting Efficiency of Water Conveyance

There are several factors that can affect the efficiency of water conveyance, including:

1. Climatic conditions: The amount of water that can be conveyed through a system can be affected by climatic conditions such as temperature, humidity, and wind speed.

2. Geometry of the conveyance system: The size, shape, and layout of the conveyance system can affect its ability to transport water efficiently. Factors such as the slope, diameter, and length of the conveyance system can all impact its efficiency.

3. Nature of the boundary of the conveyance system: The type of material used to construct the conveyance system can affect its efficiency. Factors such as the roughness, porosity, and permeability of the material can all impact the conveyance of water.

4. Method of application of water: The method used to apply water to the crops or plants can also affect the efficiency of the conveyance system. Factors such as the type of sprinkler system, drip irrigation, or flood irrigation used can all impact the efficiency of the system.

The Correct Answer

Based on the factors mentioned above, it can be concluded that the efficiency of water conveyance does not depend on the method of application of water. This means that regardless of the method used to apply water, the efficiency of the conveyance system will remain the same as long as other factors are held constant.

A free pipe outlet is a
  • a)
    rigid module
  • b)
    flexible module
  • c)
    non-modular module
  • d)
    all of the above
Correct answer is option 'B'. Can you explain this answer?

Divya Kulkarni answered
Pipe outlet discharging freely into the atmosphere is the simplest and the oldest type of a flexible outlet. The discharge through such an outlet will depend only upon the water level of the distributary, and will be independent of the water level of the watercourse.

A shaft spillway is located
  • a)
    inside the body of a gravity dam
  • b)
    inside the stream reservoir
  • c)
    inside the downstream reservoir
  • d)
    on side flanks of the main dam
Correct answer is option 'B'. Can you explain this answer?

Rajeev Menon answered
The shape of the shaft spillway is just like a funnel. The lower end of the funnel is turned at right angles and then taken out below the dam horizontally. Water spills over the circular crest and then enters the vertical shaft and comes out of the dam through the horizontal tunnel.

Conjunctive use of water in a basin means
  • a)
    combined use of water for irrigation and for hydropower generation
  • b)
    combined use of surface and ground water resources
  • c)
    use of irrigation water by cooperation of farmers
  • d)
    use of irrigation water for both rabi and kharif crops
Correct answer is option 'B'. Can you explain this answer?

Prasad Desai answered
Conjunctive use of water in a basin refers to the coordinated use of both surface water and groundwater resources. It involves managing the two sources of water in a way that optimizes their combined use and minimizes the negative impacts of their overuse.

Explanation:

Conjunctive use of water is an important strategy for managing water resources in areas where surface water and groundwater are both available. It involves using both sources of water in a coordinated manner to meet the water needs of different users while also maintaining the long-term sustainability of the water resources.

The following are some of the key aspects of conjunctive use of water in a basin:

1. Combined use of surface and groundwater resources: Conjunctive use involves using both surface water and groundwater resources in a coordinated and integrated manner. This can involve diverting surface water to recharge aquifers, pumping groundwater to supplement surface water supplies during dry periods, or using surface water to offset the overuse of groundwater.

2. Optimization of water use: Conjunctive use aims to optimize the use of water resources by balancing the demand for water with the available supply. This can involve allocating water resources based on the needs of different users, such as farmers, households, or industries, and managing the water resources to ensure that they are used efficiently and sustainably.

3. Minimization of negative impacts: Conjunctive use also aims to minimize the negative impacts of water use on the environment, including the depletion of aquifers, the degradation of water quality, and the loss of biodiversity. This can involve managing water resources to ensure that they are used in a way that minimizes their impact on the environment, while also meeting the needs of different users.

4. Collaboration among stakeholders: Conjunctive use requires collaboration among different stakeholders, including water users, government agencies, and civil society organizations. This can involve developing policies and regulations that promote the sustainable use of water resources, as well as engaging in dialogue and consultation with different stakeholders to ensure that their needs and concerns are taken into account.

In conclusion, conjunctive use of water in a basin involves managing both surface water and groundwater resources in a way that optimizes their combined use and minimizes the negative impacts of their overuse. It is an important strategy for ensuring the long-term sustainability of water resources in areas where both sources of water are available.

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