CBSE Notes Class 10 Geography Chapter 3 – Water Resources
Water is a renewable resource. It cover about three-fourth of the earth’s surface. but only a small proportion of it accounts for fresh water that be put to use.
WATER SCARCITY AND THE NEED FOR WATER CONSERVATION AND MANAGEMENT
Water scarcity means shortage of water. It is usually associated with regions having low rainfall .
There are many reasons which lead to scarcity of water:
• Growing population.
• Water scarcity is caused by over-exploitation, excessive use of water.
• Water resource are being over exploited, to expand irrigated areas for dry-season agriculture.
• There is a greater demand for water with growing urbanization and industrialization.
MULTI-PURPOSE RIVER PROJECTS AND INTEGRATED WATER RESOURCES MANAGEMENT
A dam is a barrier across flowing water that obstructs, directs or retards the flow, often creating a reservoir, lake or impoundment.
Use of dams
- Dam help in storing water for irrigation.
- Dams help in checking floods
- Dams are helpfull in development of hydroelectricity
- Water supply for domestic and industrial use
- Flood control
Side effect of creating Dams
- Villagers who reside in these areas, demarcated for the dams, are rendered homeless.
- Dams loss to cultivable land and forest areas is also immense
- Sometime a leakage in dam can be very harmful for the people who reaide these
- Sometime this dam can cause flood
- Creating of large dams has been the cause of many new environmental movements like the ‘Narmada Bachao Andolan’ and the ‘Tehri Dam Andolan’
Most of the dams were constructed to control floods but, these dams have triggered floods. Dams have also caused extensive soil erosion. Excessive use of water has resulted in earthquakes, caused water-borne diseases and pests and pollution.
India Major Rivers and Dams in the map below:
Rain water Harvesting
Rainwater harvesting is a method by which rainfall is collected for future usage.
Different methods have been adopted in different areas for Rain Water Harvesting.
- In the hills and mountainous areas of western Himalayas, people built diversion channel like ‘guls’ and ‘kuls’ for agriculture
- ‘Rooftop rainwater harvesting’ was commonly practised to store drinking water, particularly in Rajasthan.
- In the flood plains of Bengal, people developed inundation channels to irrigate their fields.
- 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.
- The tankas are part of the well-developed rooftop rainwater harvesting system and are built inside the main house or the courtyard. This is mainly practised in Rajasthan, particularly in Bikaner, Phalodi and Barmer areas for saving the rainwater. Many houses constructed underground rooms adjoining the ‘tanka’ to beat the summer heat as it would keep the room cool.
Tamil Nadu is the first state in India which has made rooftop rainwater harvesting structure compulsory to all the houses across the state. There are legal provisions to punish the defaulters