Geography class x Chapter 3 Water Resources

GEOGRAPHY –CLASS X

CHAPTER :3 WATER RESOURCES

 Important  points to remember:

1. Three-fourth of the earth’s surface is covered with water.

2. 97.5 per cent of the total volume of world’s water exists as oceans.

3. Only 2.5 per cent is fresh water.

4. Nearly 69 per cent of this freshwater occurs as ice sheets and glaciers in Antarctica, Greenland and the mountainous regions of the world,

5. 30 per cent is stored as groundwater and less than 1 per cent is in lakes and rivers.

6. Freshwater is mainly obtained from surface run off and ground water.

7. Water is continually being renewed and recharged through the hydrological cycle thus water is a renewable resource.

8. India receives nearly 4 per cent of the global precipitation and ranks 133 in the world in terms of water availability per person per annum.

Multi-Purpose River Projects and Integrated Water Resources

Management

 Important points to remember:

1. In the first century B.C., Sringaverapura near Allahabad had sophisticated water harvesting system channelling the flood water of the river Ganga.

2. During the time of Chandragupta Maurya, dams, lakes and irrigation systems were extensively built.

3. Evidences of sophisticated irrigation works have also been found in Kalinga,(Orissa), Nagarjunakonda (Andhra Pradesh), Bennur (Karnataka), Kolhapur (Maharashtra), etc.

4. In the 11th Century, Bhopal Lake, one of the largest artificial lakes of its time was built.

5. In the 14th Century, the tank in Hauz Khas, Delhi was constructed by Iltutmish for supplying water to Siri Fort area.

6. Dam is a barrier across flowing water that obstructs, directs or retards the flow, creating a reservoir or lake.

7. The Bhakra – Nangal project on Sutluj-Beas River is used both for hydel power production and irrigation.

8. Similarly, the Hirakud project in the Mahanadi basin integrates conservation of water with flood control.

9. The troubles faced by people owing to the flooding of Damodar River have given this river a name as the river of sorrow.

10.Jawaharlal Nehru proclaimed the dams as the ‘temples of modern

India’.

11.He called dams as temples because he thought they will integrate the

agriculture and village economy with industrialization and urban economy.

Q.1. Mention the important causes of water scarcity in some parts of the world ?

Ans. Water scarcity in some part of the world is  caused by:

• Due to the variations in seasonal and annual precipitation.
• water scarcity is  an outcome of large and growing population and consequent greater demands for water,
• Water scarcity in most cases is caused by over- exploitation, excessive use
•  unequal access to water among different social groups.
• Over-exploitation of groundwater for growing more crops lead to falling groundwater levels,
• The areas  where water is sufficiently available still suffers from water scarcity is due to water pollution.

Q 2 Although three-fourth of the earth’s surface is covered with water and water is also a renewable resource ,even then some regions of the world suffer from water scarcity. Explain any four reasons responsible for this.

1. About 97% of the total volume of world’s water exists as oceans. This water  is saline and not suitable for direct consumption.
2. Fresh water availability is very limited. Of the 3% of the fresh water available,70% of it is stored in glaciers and icesheets of the polar and mountainous regions
3. About 30% of fresh water stored in ground water is getting depleted due to excessive use.
4. Availability of water varies over time and space due to variations in seasonal and annual precipitation
5. water scarcity is  an outcome of large and growing population and consequent greater demands for water,
6.  Water scarcity in most cases is caused by over- exploitation, excessive use
7. Water scarcity is also caused due to the bad quality of water. Much of the fresh water has been polluted by the dumping of industrial, domestic waste,chemical fertilizers,pesticides etc

Q.2 Why the conservation and management of our water resources is needed?

Ans. The conservation and management of our water resources is necessary for:

§         To safeguard ourselves from health hazards,

§         To ensure food security,

§         continuation of our livelihoods and productive activities

§         To prevent degradation of our natural ecosystems.

§         Over exploitation and mismanagement of water resources will deplete water resource and cause ecological crisis.

Q.3 Who proudly announced the dams as the ‘temples of modern

India’.

 Jawaharlal Nehru

Q 4  Why did Jawaharlal Nehru proclaimed the dams as the temples of modern India?

Ans. The reason Jawaharlal Nehru proclaimed them as temples are:

i. Dams would integrate development of each sector of the economy.

ii. Dams were thought of as the vehicle that would lead the nation to

development and progress,

iii. They would develop agriculture and the village economy

iv. They would develop industries.

v. They would help in the growth of the urban economy.

Q 5 What are dams and how do they help us in conserving and managing water?

A dam is a barrier across flowing water that obstructs, directs or retards the flow, often creating a reservoir, lake or impoundment.“Dam” refers to the reservoir rather than the

structure. Most dams have a section called a spillway or weir over which or through which it is intended that water will flow either intermittently or continuously

dams are built not just for irrigation but for electricity generation,water supply for domestic and industrial uses, flood control, recreation, inland navigation and fish breeding.

Q 6 What are Multi purpose river valley project ?

Multi purpose river valley projects are the dams or series of dams which are constructed across rivers to impound water, which is later  used for various purposes such as Irrigation,Navigation, Generation of electricity,Pisciculture, Tourism etc.

Q 7 Why the Multi-purpose projects and large dams have come under great opposition ?

Ans. The reasons are:

Affect natural flow of running water:

i. Hence, it causes excessive sedimentation at the bottom of the

reservoir.

ii. It results in rockier stream beds.

iii. They also fragment rivers making it difficult for aquatic fauna to

migrate, especially for breeding.

 Affect natural vegetation and soil:

i. The reservoirs that are created on the floodplains also submerge

the existing vegetation and soil leading to its decomposition over

a period of time.

ii. The flood plains are deprived of silt, a natural fertiliser, further

adding on to the problem of land degradation.

Create conflicts:

i. The dams create conflicts between people wanting different uses

and benefits from the same water resources.

ii. Inter-state water disputes are also becoming common with regard

to sharing the costs and benefits of the multi-purpose project.

 Cause of many social movements:

i. They have been a cause of many new social movements like the

‘Narmada Bachao Andolan’ and the ‘Tehri Dam Andolan’ etc.

 Displacement of people:

i. They results in the large-scale displacement of local communities.

ii. Local people often had to give up their land, livelihood for the nation.

iii. This leads to widening of the social gap

iv .The local people are not benefiting from such projects.

g. Failure to control flood:

i. The dams that were constructed to control floods have triggered

floods due to sedimentation in the reservoir and at the time of

excessive rainfall.

Eg the recent flood which hit many  in the northern part of India,due to the release of excess water from Bhakra nangal ( 23^rd August 2011)

ii. It was also observed that the multi-purpose projects induced

earthquakes, caused waterborne diseases and pests and pollution

resulting from excessive use of water

h. Change in cropping pattern:

i. Availability of irrigation has also changed the cropping pattern.

ii. Farmers have shifted to water intensive and commercial crops.

iii. This has great ecological consequences like salinisation of the soil.

iv. It has increased the social gap between the richer landowners and the landless poor.

Q 8 Give examples of traditional water harvesting systems developed in ancient India.

1. In ancient India, along with the sophisticated hydraulic structures, there existed an extraordinary tradition of water-harvesting system

2. In hill and mountainous regions, people built diversion channels like the ‘guls’ or ‘kuls’ of the Western Himalayas for agriculture.

3 ‘Rooftop rain water harvesting’was commonly practised to store drinking water, particularly in Rajasthan

4 In the flood plains of Bengal, people developed inundation channels to irrigate their fields

5. In arid and semi-arid regions, agricultural fields were converted into rain fed storage structures that allowed the water to stand and moisten the soil like the ‘khadins’ in Jaisalmer and ‘Johads’in other parts of Rajasthan

Q 9 Why is the practice of rooftop  rainwater harvesting  is on the decline in many parts of Rajasthan ?

The practice of rooftop  rainwater harvesting  is on the decline in many parts of Rajasthan as plenty of water is available due to the

perennial Rajasthan Canal

Q 10 Describe how traditional rainwater harvesting is carried out in the semi-arid regions of Rajasthan

Ans. In semi-arid regions of Rajasthan traditional rainwater harvesting is carried out asfollows :

v     Almost all the houses traditionally had underground tanks or tankas for storing drinking water.

v     The tanks could be as large as a big room;

v     One household in Phalodi had a tank that was 6.1 metres deep, 4.27 metres long and 2.44 metres wide.

v     The tankas were part of the well-developed rooftop rainwater harvesting system.

v     They were built inside the main house or the courtyard.

v     They were connected to the sloping roofs of the houses through a pipe.

v     Rain falling on the rooftops would travel down the pipe and was stored in these underground ‘tankas’.

v     The first spell of rain was usually not collected as this would clean the roofs and the pipes. The rainwater from the subsequent showers was then collected.

v     The rainwater can be stored in the tankas till the next rainfall making it an extremely reliable source of drinking water when all other sources are dried up,particularly in the summers.

v     Many houses constructed underground rooms adjoining the ‘tanka’ to beat the summer heat as it would keep the room cool.

Qn 11Name a village in India which has earned the rare distinction of being rich in rainwater

    Ans Gendathur, a remote backward village in Mysore, Karnataka,

( villagers have installed, in their household’s rooftop,rainwater harvesting system to meet their water needs. Nearly 200 households have installed this system  )

Q.12  Describe how the drip irrigation system is done in Meghalaya.

Ans. 200-year-old system of tapping stream and spring water by using bamboo pipes is common in Meghalaya.

a)     Bamboo pipes are used to divert perennial springs on the hilltops to the lower reaches by gravity.

b)     The channel sections, made of bamboo, divert water to the plant site where it is distributed into branches, again made and laid out with different forms of bamboo pipes.

c)      The flow of water into the pipes is controlled by manipulating the pipe positions.

d)     If the pipes pass a road, they are taken high above the land.

e)     Reduced channel sections and diversion units are used at the last stage of water application.

f)       The last channel section enables water to be dropped near the roots of the plant.