IRRIGATION Flashcards
What is soil moisture?
Water added to a soil mass during irrigation is
held in the pores of the soil and is termed was
soil moisture.
Define crop yield and productivity.
The crop yield from irrigation is expressed as
qulntal/ha or tonnes/ha. The productivity of the
crop is expressed as crop yield per mm depth
of water applied
Explain different types of soil water.
Soil water may be classified in the following three
categories. (i) Gravitational water (ii) Capillary
water (iii) Hygroscopic water
What do you mean by capillary water?
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.
What do you mean by gravitational water?
It is that water which is not held by soil but
drains out freely under the influence of gravity.
What Is meant by soli moisture tension?
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.
What do hygroscopic water?
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.
What do you mean by soil moisture stress?
Soil moisture stress is defined as the sum of
the soil moisture tension and osmotic pressure
of soil solution.
What is kor watering, kor depth and kor
period?
The first watering after the plants have grown a
few centimeters high is known as kor watering.
What is paleo irrigation?
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.
What is lift irrigation and drip irrigation?
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.
What is irrigation?
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.
READ page 164
Read page 164
What is crop
A crop is a plant or animal product that can be
grown and harvested extensively for profrt or
subsistence.
Which soil is best for crop production
loamy soil
What is rainwater harvesting
Rainwater harvesting is a technique of collection
and storage of rainwater into natural reservoirs
or tanks or the infiltration of surface water into
subsurf~ce aquifers (before it is lost as surface
runoff)
What is alkalinity of soil? How do you reduce
it?
Alkalinity of soil refers to the presence of alkali
salts (like NaCI, Na2C03, Na2S04, 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
1.27 What do you mean by Intensity of Irrigation?
(ESE 2017
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) ~re
expr~ssed as a percentage of the CCA WhiCh
rep~el)ents_ t~e int~nsity of jrrlgation t9r the crop
. :season . .
What is check flooding?
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.
What is a furrow?
A long, narrow trench made in the ground by a
plough, especially for planting seeds or
irrigation
What is the work of NWDA?
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.
What is gross irrigation requirement (GIR)?
It is defined as the amount of water required to
meet the field irrigation requirements plus the
amount of irrigation water lost in conveyance
through the canal system by evaporation and
by seepage.
What is delta and duty? How duty varies
along length of canal?
Duty represents the area irrigated by the unit
amount of water (generally taken as 1 cumec).
It relates the area of a crop irrigated and the
quantity of irrigation water required during crop
growth. Duty increases as water moves from
canal outlet top field.
Delta is the total depth of water required for a
crop during the entire period the crop is in the
field and is denoted by 6.
command area ?
the total area that Is to be served by an irr project
. It includes cultivable and non
Name some of the barrages
Farakka barrage
Prakasham barrage
Jobra barrage
Asan barrage
2.12 Differentiate between CCA and GCA.
read from pdf
Name some Rabi, Kharif and Zald crops.
. . (ESE 2017
Khanf: R1ce. maize, mungbean g d • roun nut
cotton, soyabean, sugarcane, etc ‘
Rabi: wheat, barley,mustard, gram, tomato,
potato. etc
Zaid: Watermelon, muskmelon, bittergourd,
cucumber, pumpkin, etc
WhatisPWP?
Permanent wilting point (PWP) or wilting point
0NP) is defined as the minimal point of soil
moisture the plant requires not to wilt. If moisture
decreases to this or any lower point a plant wilts
and can no longer recover its turgidity when
placed in a saturated atmosphere for 12 hours.
What is field capacity?
ESE 2017
Reid Capacity is the amount of soil moisture or
water content held in the soil after excess water
has drained away and the rate of downward
movement has decreased.
What is carrier canal?
A carrier canal is a canal which is used for both
direct irrigation and tor feeding water to another
canal. Thus it acts as an irrigation canal as well
as feeder canal. E.g., Upper Chenab Canal in
West Punjab (Pakistan).
What is feeder canal?
A feeder canal is a canal which is constructed
only to feed another canal. No direct irrigation
is carried out from a feeder canal e.g, Indira
Gandhi Feeder canal.
What Is leaching?
In this process, land is flooded with adequate depth of water. The alkali salts present in the
soil gets dissolved in this water which percolate’
down to join the watertable. The process is
repeated till the salts in the top layer of the land
are reduced to such an extent that some salt
resistant crop can be grown. This process is
known as leaching
What do you mean by suspended load?
Sediment load is maintained in suspension due
to the turbulence of the flowing water.
What do you mean by bed load?
Sediment load moves along the bed with
occasional jumps into the channel is called bed
load.
What are the function of cross regulators?
• They facilitate communication, since a road
can be taken over them with a little extra
cost.
• The help to absorb fluctt1ations in the various
sections of the canal system, and hence
to prevent possibilities of branches in the
tail reaches.
• They help to control discharge at an outfall
of canal into another canal or lake.
• They help to control water surface slope
tor bringing the canals to regime slope and
section.
What are the drawbacks of Lacey’s theory?
The various drawbacks of Lacey’s theory are as
follows:
The true regime conditions defined by
Lacey’s are only theoretical and may not
be achieved in actual practice.
The derivation of various equations by
considering a single factor called silt factor
f is not satisfactory as there can be different
value of f for the bed and the sides.
Silt charge and silt grade have not been
defined properly by Lacey.
Lacey indicated that a true regime channel
has a semi-elliptical section but the same
is not supported by any of his equations.
By lining the canal, we mean that the earthen
surface of the channel is lined with a stable
lining surface, such as concrete, titles.
asphalt etc
3.8 What are the functlona of dlatrlbutry head regulators?
read page 168
What Is rigid boundary of canal?
Algid boundary canal: When the velocity of
flow through a canal is very small, the channel
bed does not move at all and the channel
behaves us a rigid boundary channel. As the
flow increases, a stage Is reached when the
shear force exerted by the flowing water on the
bod particles will just exceed the force opposing
their movement. At this stage, few particles of
tile bed must start moving. This condition Is
called as Incipient motion condirion