1. The document discusses various topics related to irrigation and hydrology including definitions of irrigation, the necessity of irrigation, types of irrigation projects, and methods of calculating rainfall, runoff, maximum flood discharge, and yield. 2. Key types of irrigation discussed include flow irrigation, lift irrigation, perennial irrigation, and surface irrigation methods like border strip flooding and furrow irrigation. 3. Calculating rainfall involves different measurement techniques like non-recording and recording rain gauges, while runoff is affected by factors like rainfall characteristics, topography, and can be estimated using methods like the Inglis and runoff coefficient methods.

1. CHAPTER 1 :
INTRODUCTION TO IRRIGATION AND HYDROLOGY
WEIGHTAGE: 14 Marks

2. What is Irrigation?
Artificial application of water to the land in accordance with the
crop requirement is called as Irrigation.
Necessity of Irrigation:-
1. Inadequate rainfall
2. Uneven distribution of rainfall
3. To increases yield of crop
4. Growing superior crop, perennial crop
5. Insurance against drought

3. Irrigation Engineering:-
It deals with the investigation planning, construction
management and maintenance of all structure connected with
irrigation which includes dams, diversion weirs, pumps, canal
and canal masonry work etc.
Advantages of Irrigation:-
1. Protection from Famine: By giving water and fulfilling
requirements of people during scarcity period and thus
protect them from famine.
2. Increase in food production: It helps increasing crop
yields nearly two to four times more yield more yield in dry
farming. More rounds of crop can be taken.

4. 3. Rise in social standards: With increase in crop production due
to certain supply of water it makes it possible to grow cash crops
like banana, sugarcane, tobacco, cotton etc., thus more money
will be available with the farmers which raises their standard of
living.
4. Flood control: irrigation structures like reservoirs detain floods
for some time and thus reduces destructive power and thus
helps in flood control.
5. Generation of hydroelectric power: The projects designed for
irrigation can also be designed for power generation. Canal falls
can be used for power generation.
6. Domestic water supply: Irrigation helps in augmenting the
water supply of town, where water is available with great
difficulty.

5. 7. In – land navigation: If large irrigation canals are designed then
it can also be used for navigation purpose.
8. Afforestation: Along banks of canal trees may be planted which
grows along the banks of canal and thus increases timber wealth
of country.
9. Revenue Generation: Due to direct taxes, revenue returns are
sometimes high which helps in development of country.
10. Increase in facilities of communication: The inspection path
provided for inspection may provide good roadway to villages.
11. Elimination of mixed crop: Due to assured and regular water
supply a single crop can be sown and maximum yield can be
obtained and thus eliminates mixed cropping.

6. Disadvantages of irrigation:-
1. Irrigation may result in colder and damper climate causing disease
like malaria.
2. Water logging, over irrigation may lead to water logging.
3. Salt efflorescence, due to water logging salt efflorescence occurs
which may damages land permanently.
4. Ecological imbalance.
5. Tendency towards over irrigation.
6. Excess humidity.

7. Classification of irrigation or Types of irrigation
Irrigation
Flow Irrigation Lift irrigation
Perennial Inundation Well irrigation Lift canal irrigation
Direct Irrigation Storage irrigation

8. 1. Flow irrigation: When water is available at higher level and it is
supplied to lower level under action of gravity then this type of
irrigation is called as flow irrigation.
2. Lift irrigation: In this type of irrigation system water is lifted by
some mechanical or manual means such as pumps etc. and then it
is supplied for irrigation this type of irrigation is called as lift
irrigation.
3. Perennial irrigation: In perennial type of irrigation water is
supplied in accordance with requirement of crop throughout crop
period. In this system storage head work such as dams, weirs or
barrages etc are constructed to store water and it is supplied
through canal distribution system.
4. Direct irrigation: In direct irrigation the water is directly taken
from river by constructing weir or barrages and thus increases
level of water and diverting it to canal.

9. 5. Storage irrigation: In this type of irrigation a solid barrier such
as dam or storage weir is constructed and across river to store
water during monsoon so as to supply water in off taking channels
during period of non monsoon or scarcity.
6. Flood irrigation/ Inundation irrigation: This type of
irrigation is possible only during occurrence of floods in a year. In
such type, irrigation work is not required across the river.

10. Methods of Irrigation:-
1. Sub surface irrigation
2. Surface irrigation
3. Over head irrigation

11. 1. Sub surface Irrigation: In this method water is carried below the ground
level either connects to water table with which it increases water table and
saturate root zone of the plants or directly to plant roots through drains or
pipes.
Types:-
a. Natural sub surface irrigation: When water is applied to the plants
through capillary movement from water table then it is called as natural sub
surface irrigation.
b. Artificial Sub surface irrigation: In this method water from drains and
pipes directly infiltrate into root zone of soil.
2. Surface Irrigation: In this method of irrigation water is flooded over the
field to a few cm. And to control flow the surface is first smoothened and
then modified with borders furrows corrugations etc.
Types:-
a. Uncontrolled or free flooding method
b. Controlled flooding methods
c. Furrow methods
d. Drip irrigation

12. a. Uncontrolled of free flooding methods:- In this method water is applied by
flooding over areas of smooth and flat land. This method is adopted in
inundation irrigation system. This method may cause wasteful use of water.

13. b. Controlled flooding method: In this method of irrigation water is applied
to the field in different quantities at different types and thus flow controlled
is of an steady type.
In this type water is supplied through various methods the various methods
are as follows:
i. Border strip/ border flooding
ii. Basin method
iii. Check method
iv. Ditch method

20. c. Furrow methods: In this method water is applied only one fifth to one half
of land surface which results in less evaporations.
I this method narrow fields ditches excavated between rows of plant which
carries irrigation water through them. Furrows are generally 8 to 30cm deep
and may be as much as 400m long.
Types:
i. Graded furrow method
ii. Contour furrow method
iii. Level furrow method
iv. Corrugation method

24. d. Drip irrigation: In this method irrigation is done by using small diameter
plastic lateral lines called as dippers. It is also called as trickle irrigation.
It is suitable for areas where there is actual scarcity of irrigation water and
other salt problems occurs.
In this method water is directly applied to the root zone of the plants through
drip nozzles when are placed at an interval of about 0.5 to 1 m. These emitters
discharged water at very small rates of 2 o 10lit/hr.

27. 3. Overhead Irrigation: The overhead irrigation is divided as sprinklers
irrigation. In this method water is applied to the soil in the form of spray through a
network of pipes and pumps. It is a kind of artificial rain.
Efficiency is more than 80% as there is uniform distribution of water.
Suitable where land topography is irregular, gradient is steep and soil is easily
erodable.

30. Types of Irrigation Project
a. Based on administration
1. Major Projects
2. Medium Projects
3. Minor Projects
Sr. No Name Estimated cost According revised
classification
1 Major Project Above Rs. 5 Crore CCA more than
10000 ha
2 Medium Project Between 25 lakhs to
5 Crore
CCA between 2000
to 10000 ha
3 Minor Project Below 25 lakhs CCA less than 2000
ha

31. b. Based on purpose wise:
i. Single purpose project: A project which is planned and financed for one or
single objective it is called as single purpose project.
Example: Koyna project- for hdyro power
Bagh project- for irrigation
ii. Multi purpose project: when a project is planned for more than one objective it
is called as multipurpose project.
Example: bhakranangal- for irrigation and power generation

32. HYDROLOGY
It is the science which deals with the occurrence distribution and circulation of water on
earth.

33. Rainfall:-
Rainfall is depth in mm or cm of water that would stand on the surface of earth
if it is not lost in any manner like evaporation, absorption etc.
Rain gauge:
It is the instrument used to measure the rainfall at a place.
Rain Gauge station:
The place at which rain gauges are installed for measurement of rainfall is
called as rain gauge station.

34. Site selection for rain gauge station:-
1. Site should be in open space having at least an area of
5*5.5m.
2. The distance of instrument from nearest obstruction should
not be less than 30m or twice the height of obstruction.
3. The gauge should have level horizontal catch surface.
4. A fence should be erected around rain gauge station , to
protect it against cattle and dogs etc.
5. A site that is sheltered from high wind should be chosen.
6. The gauge must be mounted firmly so that it can not be
disturbed even by strong wind.
7. The distance of fence should not be less than twice of its
height.

36. Types of rain gauges:-
1. Non recording Type
a. Symon’s rain gauge
2. Recording Type (Automatic rain gauge)
a. Weighing bucket gauge
b. Tipping bucket gauge
c. Syphon gauge (float type rain gauge)

51. ARITHMETIC AVERAGE (MEAN METHOD)

56. THIESSEN’S POLYGON METHOD/REPRESENTATIVE AREA METHOD

62. ISOHYTEAL METHOD

66. RUNOFF

67. FACTORS AFFECTING RUNOFF:-
1. Rainfall Characteristics
2. Topography
3. Geology
4. Surface condition
5. Storage Condition
6. Shape of Catchment
7. Meteorological Condition

68. CALCULATION OF RUNOFF:-
1. Inglis method
2. Strange’s method
3. Binnie's method
4. Runoff coefficient method
1. Inglis Method:
a. For ghat areas
R(cm) = 0.84P-30.54 , where P is more than 200cm
b. For non-ghat areas
R(cm) = P(P-17.74) , where P is less than 200cm
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2. Runoff Coefficient:
It is applicable only for small projects. It is given by:-
R=kp
Where, R = runoff in cm
p = rainfall in cm
k = Runoff coefficient

69. MAXIMUM FLOOD DISCHARGE (MFD):-
MFD is maximum concentration of flow from a catchment area at the outlet in a
small period
It is expressed as volume per unit time i.e. m3/s. cumecs or cubic meter per
seconds
MFD gives maximum discharge of river during flood which is useful for safety of
reservoir.
FACTORS AFFECTING MAXIMUM VALUE OF MFD
1. High intensity of rainfall
2. Late in rainy season
3. Uniformly spread rainfall in large extent of CA
4. Fan shaped catchment area
5. Steep slope
6. Rockey soil
7. Downstream (D/S) direction of the wind.

70. METHODS OF ESTIMATION OF MFD:-
1. Inglis Method: It is applicable to western Maharashtra and Gujarat for fan shaped
catchment.
Q= 125M or 12
√ M+10.24 √A + 10.24
2. Dicken formula (Applicable to central india)
Q= CM3/4 or Q= CA 3/4
where, C= 2 to 40 constant
Q = MFD in m3/s
A = Catchment area in km2
3. Khosala’s Formula
R= D-L
where, R= runoff
L = loss
D= rainfall

71. 4. Myer’s formula:-
Q= 175 A
Where Q = MFD in m3/s
A= area of catchment in km2

72. YIELD:-
It is total quantity of water available from a catchment area at the outlet in
period of one year. It is expressed in Mm3 (million cubic meters) or ha.m Is
called as yield.
DEPENDABLE YIELD:-
It is assured yield. It is the quantity of water available for a given number of
years per rainfall cycle. Yield calculation is important as storage capacity is
depend upon the yield.
Yield can also be calculated from analysis of rainfall but it gives only
approximate values.

73. • GOOD YEAR RAINFALL: 120% OF AVERAGE
RAINFALL
• BAD YEAR RAILFALL: 80% OF AVERAGE
RAINFALL.