CHAPTER 3: WATER RESOURCES

Important Terms

• Dam: It is a concrete wall constructed across the river to stop the river water. The storage of water behind the dam is called reservoir.
• Perennial River: A river having water throughout the year is called Perennial River. Their water source is melting glaciers, e.g. Ganga, Brahmaputra etc.
• Reservoir: Large collection of river water just behind the dam is called reservoir.

Water Resources in India

• Annual rainfall in India is about 117 cm. Cherapunji receives highest rainfall in the world.
• India has many perennial rivers e.g. Ganga, Yamuna, Indus, Brahamputra etc. Seasonal rivers of southern India e.g. Godawari, Krishna, Kauveri, Narmada etc are also good source of water.
• India has long seacoast. It is more than 6000 km. Arabian Sea, Bay of Bengal and Indian Ocean surround southern India from three sides.
• India is also rich in groundwater resources. There are many natural and man-made lakes, ponds, hydraulic structures etc found in our country.
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Water Scarcity and Its Causes

Water Scarcity: When water is not available in sufficient quantity and quality for all the people in an area, it is called water shortage or water scarcity. Water scarcity leads to drought and famine and claims thousand of lives every year in India. Followings are the causes of water scarcity.

a)    Amount of rainfall less than the normal

b)    Over exploitation of ground water by tube wells in the cities

c)     Excess use of water for irrigation to grow more crops.

d)    Water pollution by dumping of waste from city and industries

e)    Flood [Water is polluted and become unfit for use]

Multipurpose Projects and Its Advantages and Disadvantages

Meaning: A river valley project having many dams, barrages, canals etc is called as multipurpose project. It is called multipurpose because it serve many purposes and solve many of our problems. Example: Bhakharan Nangal Project, Damodar Valley Project etc.

Advantage of Multipurpose Projects

a)    Multipurpose projects provide water for irrigation of crops.

b)    They control the flood in the river. Damodar River was called ‘Sorrow of Bengal’. Now, it is a blessing for that region.

c)     Multipurpose projects also provide facility for afforestation and conservation of soil from erosion.

d)    Hydroelectricity, the cheapest source of emery, is produced from multipurpose projects. About 22% electricity comes from this source in India.

e)    Canals and reservoir can also be used for water transportation and fisheries.

Disadvantage of Multipurpose Projects

a)    Fertile agricultural land submerged under the river water.

b)    Large no. of people are displaced. They have to leave their own houses and properties.

c)     Forest land are either cleared or submerged under water. It is great loss for environment.

d)    Siltation in the dam reduces the life span of the project.

e)    Big multipurpose projects can result into minor earthquakes.

Rainwater Harvesting and Its Objectives and Methods

Meaning: Capturing and storing the rainwater for recharging the ground water is called rainwater harvesting. Rainwater can also be used for domestic and agricultural purpose. It is a good method of water conservation in water scarcity areas such as Rajasthan. Rainwater is collected on the roof of house and it is stored in dug well or underground tank. This water is used for washing, animal drinking, irrigation etc.

Objectives of Rainwater Harvesting

a)    To reduce surface run-off which cause flooding on the roads.

b)    To meet the increasing demand of water.

c)     To recharge the groundwater.

d)    To reduce groundwater pollution and improve the quality of water.

e)    To supply water during dry season.

Methods of Rainwater Harvesting

a)    Collecting rainwater on roof top and diverting it into a dug well to recharge groundwater.

b)    Collecting rainwater on roof and bringing it underground tank in the house for domestic use.

c)     Making small check dams to stop surface run-off and allow the soil to absorb more moisture.

d)    Using bamboo as pipe to bring spring water from far away place for irrigation like in Meghalaya.

Different Methods of Rainwater Harvesting in India

• In Rajasthan, rainwater is collected on the roof tank to store drinking water.
• Farmer of Rajasthan collects rainwater in their agricultural fields to increase the soil moisture. It is called ‘Khadins’ and ‘Johad’ in Rajasthan.
• People of Rajasthan, also built underground tank [Called as ‘Tankas’] to store drinking water for at least a year.
• In West Bangal, people developed inundation channels to irrigate their fields.
• In the hilly and mountainous areas, people build diversion channel called as ‘Guls’ and ‘Kuls’ for development of agriculture.
• Collection of rainwater is also done in Shillong for household requirement.
• In Meghalaya, people use bamboo [Bamboo Drip] as pipes to bring water spring water located hundreds of meters away from the houses.
• Tamil Nadu is the first state to make rooftop rainwater harvesting compulsory in every house across the state.

Watershed Development:

An area drained by an tributary is called watershed. All round development of this area is called watershed development. Sukhmajri Village in Haryana is the best example of watershed development. Attempt made under watershed development are:

• Conservation of soil and moisture,
• Afforestation and forest upgradation,
• Water harvesting,
• Development of horticulture
• Pasture development
• Supply of drinking water