Water Resources
Water Resources
The process of supplying water by artificial means is called irrigation.
Irrigation is essential in India because…
1. India is an agricultural country. Hence, round the year supply of
water is essential.
2. Rainfall is insufficient and unevenly distributed.
3. India has a year long agricultural season, but the rainfall is seasonal.
Thus, irrigation ensures year long cultivation.
4. Crops like rice, wheat, Jute and sugarcane require plenty of water
which can be provided only through irrigation.
5. Due to growing population. There is a great demand for food which
is fulfilled by bringing all possible regions under cultivation and
providing irrigation to them.
6. Some parts of India are drought prone and are known for uncertain
rainfall. Irrigation becomes indispensible in such parts of the nation.
Methods of Irrigation
Traditional Methods include
wells, tanks & inundation
canals
Modern Methods: Sprinkle
and Drip irrigation.
Primitive methods
Tank Irrigation
Primitive method
Shadoff
Wells: Wells are an age old method
Well of Irrigation
providing water for
agriculture, for drinking and for
household purposes.
A hole is dug in the ground to
obtain sub-soil water.
Wells are found where:
(a)Sufficient groundwater is
available.
(b)Groundwater level is not very
deep.
(c) Soil is soft.
Well irrigation is concentrated in
the states of Uttar Pradesh,
Punjab & Rajasthan
• Advantages of Wells
1. Wells are the simplest & the
cheapest means of irrigation.
2. Wells can be dug at any
convenient place.
3. It is an independent source of
irrigation.
Disadvantages:
1. Wells dry up during summer
and fail to provide water
when needed the most.
2. A well can irrigate only 1 to
2 hectares of land.
3. Well water is brackish.
An earthen or concrete wall is constructed across a
stream or depression to form a Tank.
Tank irrigation is practiced in the
peninsular plateau in the states
of Andhra Pradesh & Tamil
Nadu.
Tank irrigation is important in
the Deccan Peninsula because:
1. The land is undulating and
forms natural depression.
2. The underlying hard,
impervious rocks prevent
the percolation of water.
3. Tanks enable people to
arrest the river water
which otherwise flows
away.
Advantages of tanks
1. They are naturally formed so there is no need of construction and
hence they are cheap.
2. In South India they are found in more number where there are
very few perennial rivers.
3. It stores the rain water which otherwise will flow away and get
wasted.
4. This water can be used for irrigation and for domestic purposes.
Natural Tanks
Disadvantages of Tank
Irrigation
1. Tanks occupy a large surface area, which could otherwise have
been used for cultivation.
2. Many tanks dry up during dry season and fail to provide water
when it is required most.
3. Silting of tanks is a problem and desiliting is often needed
Dried Tank
Soil flows down the slope and collect in the tank
decreasing its water storing capacity
Modern
Methods of
Irrigation
These are most
reliable & provide
irrigation whenever
needed. They are
easy to operate, and
irrigate a larger
area.
They are operated
by a well designed
regulatory system or
technology.
Tube wells: Tube wells are
introduced in the Indo-
Gangetic plains where ground
water is ample and available
close to the surface.
A very deep bore ,about 15
meter is dug and water is
lifted with an electric or diesel
pump.
Tube well: Hand pump
Advantages of Tube wells
1. Tube wells irrigate much larger area of about 400 hectares.
2. They are more reliable during summer or drought conditions
where ordinary wells dry up.
3. They are also suited for small land holdings.
Limitations of Tube wells
Tube wells are feasible in the following situations
1. There must be sufficient groundwater.
2. There must be regular supply of cheap electricity.
3. The land must be fertile & productive so that the
cost of operation can be recovered from increased
farm production.
States: Tube wells are widely used in Uttar Pradesh,
Bihar, Punjab, Haryana, Rajasthan, West Bengal,
Andhra Pradesh & Gujarat
Canals
Canals are drawn either from Dams(Perennial canals) or by
directly cutting the banks of the rivers( Inundation canals).
The digging of canals in rocky and uneven areas is difficult.
Therefore canals are practically absent in Peninsular India. More
than 15 million hectares of land in our country are irrigated by
canals.
39 % of irrigation in India is done by canals.
Inundation
canals
• These are flood water canals and have water in them when river is
flooded during the rainy season.
• These canals are directly taken out by cutting the river banks.
• They do not have any regulating systems like weirs or
embankments.
• Inundation canal are found in large number on river Satluj.
Many inundation canals are
converted to Perennial canals
Merits of Canal
Irrigation
1. Most of the canals are perennial and provide water whenever
needed.
2. Canal water is loaded with sediments which increase the
fertility of the soil.
3. Barring initial cost,canal irrigation is quite cheap.
Demerits of Canal Irrigation
4. If canals are not lined, canal water seeps underground and
causes water logging.
5. Underground salts occupy the upper surface of the soil and
makes the soil ‘reh’ i.e. saline. Ex.Punjab, Uttar Pradesh,
Haryana.
6. Marshy areas near the canals become the breeding ground for
mosquitoes which spread Malaria.
Perennial Canal
Indira Gandhi Canal
Sprinkler
Irrigation
It is a type of overhead
irrigation. Water is
supplied through
hoses(pipes).Thus there is
no seepage. There is no
loss by evaporation since
water is supplied directly
on to the field by sprinkler.
This method is practiced
in arid, semi-arid and hilly
areas. It is expensive.
Water Conservation
Conservation of water is essential due to its short supply, increased
demand,large-scale pollution & uneven distribution.
Measures:
1. Developing water saving technologies.
2. Prevent water pollution.
3. Encourage watershed development,rain-water harvesting, reuse
& recycling of water.
Watershed Development
Tanks,ponds, check-dams and
similar structures have been
constructed for water harvesting.
Under this programme, the rain
water is arrested and allowed to
percolate underground to raise
the level of ground water i.e.
Water Table.
Objectives of Rain water
Harvesting-
1. To meet the increasing
demand of water.
2. To reduce surface run-off.
3. Avoid flooding of roads.
4. To raise the water table.
5. Improve the quality of
ground water.
6. Reduce soil erosion.
7. To fulfill the household
requirement of water during
hot summer.
Roof water
harvesting
Tamil Nadu is one
state which has made
it mandatory for
every building to
harvest rain water.
Rain water can also
be harvested by
methods like
recharging hand-
pumps, recharge
through trenches and
stop dams on small
streams
Water Harvesting Methods in
India
Aquifer- It is an underground layer of permeable rock
which holds water.
Johad- Is a crescent shaped bund built across the
catchment area to capture surface runoff in
Rajasthan.
Hariyali- A project to arrest and percolate the
rainwater sponsored by central government and
implemented by Gram panchayats with peoples
participation.It is called “ Jalyukta Shivar” in
Maharashtra.
Neeru-Meeru- Launched in Andhra Pradesh to
harvest rainwater and percolate underground.
Recharge Pit
Recharge Trench
