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IRRIGATION > ASDqwdqed > Flashcards

ASDqwdqed Flashcards

1
Q

Define crop yield and productivity.

A

The crop yield from irrigation is expressed as

quintal/ha or tonnes/ha. The productivity of the crop is expressed as crop yield per mm depth of water applied.

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2
Q

What is soil moisture?

A

Water added to a soil mass during irrigation is

held in the pores of the soil and is termed was soil moisture.

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3
Q

Explain different types of soil water.

A

Soil water may be classified in the following three

categories. (i) Gravitational water (ii) Capillary water (iii) Hygroscopic water.

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4
Q

What do you mean by gravitational water?

A

It is that water which is not held by soil but

drains out freely under the influence of gravity.

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5
Q

What do you mean by capillary water?

A

It is that the water which is retained in the soil
after the gravitational water has drained off from the soil. Capillary water is held in the soil by surface tension as a continuous film around the soil particles and in the capillary pores between the soils particles

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6
Q

What do hygroscopic water?

A

It is that water which is absorbed by the
particles of dry soil from the atmosphere and it held as a very thin film on the surface of the soil particles due to adhesion or attraction between surface of particles and water molecules.
Note: Below the permanent wilting point, the soil contains only hygroscopic water.

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7
Q

What is meant by soil moisture tension?

A

Soil moisture tension is defined as the force per
unit area that must be exerted in order to extract
water from the soil. In other words, it is a measure of the tenacity with which water is retained in the soil.

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8
Q

What do you mean by soil moisture stress?

A

Soil moisture stress is defined as the sum of

the soil moisture tension and osmotic pressure of soil solution.

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9
Q

What is paleo irrigation?

A

It is defined as the watering done prior to the
sowing of a crop. This is done to prepare the land for sowing and to add sufficient moisture to the soil which would be required for the initial growth of the crop.

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10
Q

What is kor watering, kor depth and kor period?

A

The first watering after the plants have grown a few centimeters high is known as kor watering.

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11
Q

What is irrigation?

A

Irrigation is the artificial application of water to the land or soil. It is used to assist in the growing of agricultural crops, maintenance of landscapes, and revegetation of disturbed soils in dry areas and during periods of inadequate rainfall.

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12
Q

What is lift irrigation and drip irrigation?

ESE 2012

A

Lift irrigation: Lift irrigation is a method of

irrigation in which water is not transported by natural flow (as in gravity-fed canal systems)
but is lifted with pumps or other means.
Drip Irrigation: Drip irrigation is an irrigation method that saves water and fertilizer by allowing water to drip slowly to the roots of plants, either onto the soil surface or directly onto the root zone, through a network of valves, pipes and emitters. It is done through narrow tubes that deliver water directly to the base of the plant.

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13
Q

Give the examples of east flowing rivers and

west flowing rivers?

A

East flowing rivers in India are Brahamaputra,
Ganges, Godavari, Krishna, Cauvery, Mahanadi, Baitarni, Penner etc.
West flowing rivers in India are Tapti, Narmada, Sabarmati, Indus, Sutlej, Ravi, Beas etc.

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14
Q

What is the difference between open well

and tube well?

A

Open well: These are open masonry wells of
comparatively larger diameter which are suitable for low discharges of 1 to 5 liters per second. The diameter of these wells usually varies from
2 to 9 meters and are generally less than 20 m in depth.
Tube well: Since discharge from an open well is quite small, it is not suitable to have large discharges from open well. Large discharge is obtained mechanically by the use of tubewell which is a long tube bored or drilled deep into the ground which intercepts one or more water bearing strata.

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15
Q

Difference between cumec and cusec.

A 
Cumec = 1 m3/sec
Cusec = 1 feet3/sec
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16
Q

What are the various quality parameters of

irrigation water? (ESE 2016, 20 17)

A

Water quality parameters to be assessed for
irrigation are:
(i) Sediment concentration in water.
(ii) Total concentration of soluble salts in water. (iii) Proportion of sodium ions to other cations.
(iv) Concentration of potentially toxic elements
present in water.
(v) Bicarbonate concentration as related to the concentration of calcium plus magnesium.
(vi) Bacterial contamination.

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17
Q

How can we rectify water logging?

A

We can rectify water logging by:
• Increasing soil organic matter levels.
• Reducing tillage.
• Increase amount of surface cover to reduce
the amount of surface sealing on the soil — this also assists in reduction of water loss through evaporation
• Using raised beds.
• Adding gypsum.

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18
Q

What is crop?

A

A crop is a plant or animal product that can be

grown and harvested extensively for profit or subsistence.

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19
Q

What are the disadvantages of irrigation?

A 
Water logging
• 	Salinity and alkalinity of land
• 	Aeration of soil
• 	Pollution of undergroundwater
•

Results in colder and damper climate

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20
Q

What are the advantages of drip irrigation?

A

Erosion of soil does not take place. Evaporation of soil is minimum.
No runoff of water and fertilizer.

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21
Q

Define Infiltration Gallery.

A

Infiltration gallery: An infiltration gallery is a

structure generally consists if perforations which aims to tap groundwater near the river banks.

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22
Q

Which soil is best for crop production?

ESE 2016

A

Loamy soil is considered the best soil for crop
production as it contains silt, sand and clay with high organic matter. Also it contains all the necessary elements required by the crops.

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23
Q

What is smart irrigation?

A

Smart Irrigation: Smart irrigation aims to have
efficient use of water along with to minimize the environmental impact. It makes use of improved technologies which ensure sustainable and optimal use of water.

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24
Q

What is alkalinity of soil? How do you reduce

it?

A

Alkalinity of soil refers to the presence of alkali
salts (like NaCI, Na2CO3, Na2SO4, etc.) in the soil. These salts are soluble in water. If the water table rises up, the soluble alkali salts move up with water and get deposited in the soil.
Alkalinity of soil can be reduced by leaching.

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25
Q

What is rainwater harvesting?

A

Rainwater harvesting is a technique of collection
and storage of rainwater into natural reservoirs or tanks, or the infiltration of surface water into subsurface aquifers (before it is lost as surface runoff).
1.27 What do you

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26
Q

What do you mean by intensity of irrigation?

A

Intensity of irrigation is defined as the
percentage of the irrigation proposed to be irrigated annually. Usually the areas irrigated during each crop season (Rabi, Kharif, etc) are expressed as a percentage of the CCA which represents the intensity of irrigation for the crop season.

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27
Q

What is lift irrigation?

A

Lift Irrigation is a method of Irrigation in which
water instead of being transported by natural flow (as in gravity-fed canal systems) requires external energy through animal, fuel based or electric power using pumps or other mechanical means.

28
Q

What is the need of lift irrigation?

A

When water is not available at higher level to be

supplied to lower level by mere action of gravity then lift irrigation is needed.

29
Q

What is a furrow?

A

A long, narrow trench made in the ground by a

plough, especially for planting seeds or irrigation.

30
Q

What is check flood ing?

A

The crop area is divided into some plots which
are relatively leveled by checks or bunds. Water from field channels is allowed to enter to each plot or check basin and the plot are flooded to the required depth

31
Q

What is the work of NWDA?

A

National Waterway Development Agency
(NWDA) is an autonomous body set up in July 1982 to carry out water balance and other studies based on scientific approach and optimum utilization of water resources of the Indian river system and thus to help in development of Indian river system.

32
Q

What is consumptive irrigation requirement

(CIR)?

A

that is required to meet the evapotranspiration needs of a crop during its full growth.
CIR = (Cu - Re)
Where Cu = consumptive use of water Re = effective rainfall

33
Q

Why we provide lined canals in place of

unlined canals? (ESE 2013)

A

Lined canals are provided w ith a lining along
the perimeter throughout the ir length so as to increase the flow velocity and reduce seepage
their movement. At this stage, few particles of the bed must start moving. This condition is called as incipient motion condition.

34
Q

Lined and unlined canals? Losses and

control through unlined canals.

A

Lined canals: In lined canals, the canal bed
as well as the canal boundary is lined with some impervious material like cement concrete, tile, bricks etc. so as to reduce the percolation loss of water and to increase the canal capacity. Unlined canals: Here neither the canal bed nor the canal side slopes are lined. This type of
canal cannot check the loss of water due to percolation and often leads to water logging the nearby areas.

35
Q

What are the formulas to determine Ans.

discharge in canal?

A

ischarge in the canal is computed using the
following two empirical formulae:
Manning’s formula
2/, r-

rce Engineering

169

Q	—AR'JNIS
n
where
Q = Discharge in the canal
n = Manning's roughness coefficient
A = Cross sectional area of flow in the canal
R = Hydraulic mean depth or Hydraulic
radius = A/P
P = Wetted perimeter of the canal cross-section S = Slope of energy grade line which is equal to slope of canal bed in case of uniform flow
Chezy's formula
Q = AC RS
Where C = Chezy's constant
36
Q

What is true regime?

A

True regime: A channel is said to be in true
regime if there is no silting and no scouring. This condition is attained when silt load entering the channel must be carried through the channel section.

37
Q

What is a Canal?

A

Canals, or navigations, are human-made

channels, or artificial waterways, for water conveyance, or to service water transport vehicles.

38
Q

Define carry-over storage.

A

The storage of water (say, about 5% of live
storage) required for the next crop-year as a protection against the late monsoon break is referred to a carry-over storage.

39
Q

What are different forces on gravity dam?

A
  • Water pressure
  • Uplift pressure
  • Pressure due to earthquake forces
  • Silt pressure
  • Wave pressure
  • Ice pressure
40
Q

What are the requirements of a good

module?

A

Module should be simple, so that it can be
easily constructed or fabricated by local masons or technicians.
• Module should work efficiently with a small
working head.
• The outlet should be cheaper, since they
are required in large number.
• The outlet should be such as to avoid
interference by cultivators, thus preventing under tapping of water by cultivators.
• It should draw its fair share of silt

41
Q

What are the types of outlets (modules)?

A

The various available types of outlots can be
classified into throe classes:
Non-modular outlote:
•

5.5 What are Canal falls?

Non-modular outlets aro those through
which tho discharge depends upon the Ans. difforonco of hoed botwoon tho distributary and tho water course.
Seml-modular outlets (or flexible):
•
Somi-rnodular aro those through which tho discharge Is independent of the distributary

so long as a minimum working hoad Is available.
Modular outlets (or rigid modules):
•
5.6 What are aqueduct, syphon aqueduct?
(ESE 2014) Ans. Aqueduct: Cross d rainage work in which bed

•
Modular outlets are those through which the discharge is constant and fixed within limits, irrospectivo of the fluctuations of the wator lovols of either the distributary or of tho water course of both.
5.7
Common example of this type of modules Is Gibb’s module.

42
Q

What are the advantages of Siphon Spillway?

A

Tho following are the advantages of a siphon
spillway over the other types of spillways.
• It is able to pass full capacity discharges
with narrow limits of head water rise.
• It is automatic in action without involving
any mechanical devices or moving parts.
• Its discharge per unit length is more
because it has a higher operating head.
• There is practically no maintenance cost
and it is leak proof.
• The cost of acquisition of areas which will
get submerged between maximum water level and full reservoir level is minimum in this case.
• The height of the dam above the crest of
the spillway is also reduced significantly.
• It is useful in sucking up sediment from
the bed of the reservoir when it is in full action during floods

43
Q

What are the disadvantages of Siphon

Spillway?

A

Tho following are the limitation of a siphon
spillway.
• It is unable to pass ice and debris.
• There Is a possibi lity of clogging of the
siphon duct and siphon breaker vents with debris or leaves.
canal for the following reasons:
• To pool up the water on the upstream side
so as to divert the stored water into the canals for irrigation and water supply purposes.
• To protect the river water from flooding the
downstream areas by releasing the upstream water in a controlled manner.

44
Q

What are the effects of silting in reservoir

operation?

A

The deposition of sediment in the reservoir
i.e. silting reduces the effective storage of reservoir.
• Also with the passage of time, the reservoir
capacity goes on reducing and the stage may reach when whole reservoir may get silted up.
• With reduced capacity of reservoir, the
effective head of water decreases which have an adverse effect on the power generation by turbines.

45
Q

What are various cross drainage works?

A

Cross drainage works is a structure constructed
when there is a crossing of canal and natural
drain, to prevent the drain water from mixing into canal water. This type of structure is costlier one and needs to be avoided as much as possible.
There are three types of cross drainage works structures:
Type — 1: Cross drainage work carrying canal over the drain
The structures falling under this type are: Aqueduct, Syphon Aqueduct
Type — 2: Cross Drainage work carrying Drainage over the canal
The structures falling under this type are Super passage, Canal Syphon
Type —3: Cross drainage works admitting canal water into the canal
The structures falling under this type are Level Crossing Canal inlets

46
Q

Differentiate between siphon and aqueduct.

A

When the HFL of the drain is sufficiently below
the bottom of the canal, so that the drainage water flows freely under gravity, the structure is known as an Aqueduct.
If the FSL of the canal is sufficiently above the bed level of the drainage trough, so that the canal flows under syphonic action under the trough, the structure is known as a canal syphon.

47
Q

Define causeway, aqueduct, culvert.

ESE 2016

A

Causeway: Whenever a road embankment is
constructed across a flat terrain, in order to drain off the runoff collected on the road side, the road on the embankment is lowered to the natural ground level at frequent intervals thus allowing water to flow across the road. This is called as causeway.
Aqueduct: An aqueduct is an arrangement wherein the canal water is carried above the d rain/river.
Culvert: A culvert is usually any bridge with span less than 8 m.

48
Q

What are diversion headworks?

A

These are the works which are constructed at
the head of the canal in order to divert the river water towards the canal so as to have a regulated and continuous supply of silt free water with a certain minimum head in to the canal.

49
Q

What is a Super Passage?

A

When the canal is in full cutting and there is
sufficient head way for the canal water a Super Passage may be proposed. That is if the Full supply level (F.S.L) of canal is below a depth of free board required for canal from bed level of drain crossing, at this point a super passage may be constructed to let the discharge of drain without causing any damage to the canal.
5.15 What are cross-drainage works?

50
Q

What are cross-drainage works?

(

A

When a natural drain crosses or intercepts an
irrigation canal it becomes necessary to construct some suitable structure to carry forward the canal safely. As these works are constructed for crossing the drainage, they are termed as cross drainage work.

51
Q

Why are weep holes provided and where are

they used?

A

Weep holes are used to dispose off the drainage

water that has managed to seep into the dam. Weep holes acts as safety provider to the dam.

52
Q

What is aggrading type river?

A

An aggrading river is a silting river. Such a river

increases its bed slope, which is called building up of slope.

53
Q

What is degrading type river?

A

If the river bed is constantly getting scoured to reduce and dissipate available excess land
slope then the river is known as a degrading river.

54
Q

What is degrading type river?

What is stable type river?

A

River which does not change its alignment, slope and its regime significantly is called a stable river.

55
Q

What do you mean by flashy rivers?

A

If the flood river and flood fall in a river is sudden, then it is called a flashy river. In flashy rivers, the flood flows, occur suddenly and rise and fall of water level is very quick.

56
Q

What is virgin rivers?

A

In arid zones, a river water may completely dry before it joins another river or the ocean. Such a river is called a virgin river.
What is band

57
Q

What is bandalling?

A

Bandalling is a method of river training which is generally used to confine the low water flow in a single channel for maintaining required depth for navigation.

58
Q

What are the different river training works? (ESE 2017)

A 
Different river training works are:
• 	Embankments
• 	Guide banks
• 	Spurs or groynes
• 	Cutoffs
• 	Bed pitching and bank reactment
59
Q

What is river water train ing?

A

In easy words river training means to guide and confine the flow to the river channel, and to control and regulate the river bed configuration, thus ensuring safe and effective disposal of

60
Q

What is the purpose of pitching of banks of

river?

A

of rivers by laying stones or concrete blocks. Mostly stone pitching is adopted if stones are locally available. Pitching makes the river banks more resistant against erosion.

61
Q

What is pitching in river? How is it done?

A

Pitching in river: Pitching is a river training work
wherein the river banks are protected by stone pitching or by concrete blocks or brick lining.
• For pitching, the banks of the river are first
made stable with slope varying from 1:1 to 2: 1.
• The banks are then pitched so as to make
them rough enough to resist the erosion action of river.
7.11 What is trap efficien

62
Q

What is trap efficiency?

A

It is defined as the percentage of the sediment

deposited in the reservoir even inspite of taking precautions and measures to control its deposition.

63
Q

What are different types of weir?

A 
Different types of weir: Weirs are broadly
classified as:
• 	Broad crested weir
• 	Sharp crested weir
-	Rectangular weir
-	Triangular weir
-
64
Q

Why rivers changes their courses in 50 to

100 years?

A

Rivers change their course because when the
silt charge is in excess quantity then that required for stability, the rivers start building up their own slope by depositing the silt on the river bed. Thus the river reach becomes an aggrading type. This aggrading is the main process which leads to change in the river course.

65
Q

Why is rip-rap provided?

A

Rip-rap: Rip-rap is the range of rocks place
along the coast line in order to protect the structures located along the coast line. The size of the rocks used range from 100 mm to over 600 mm.

66
Q

Why fish ladders are provided?

A

A fish ladder, also known as a fishway, fishpass
or fish steps, is a structure on or around artificial and natural barriers (such as dams, locks and waterfalls) to facilitate diadromous fishes’ natural migration.

IRRIGATION (3 decks)

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