Class 10th
- 2. Water resources are natural resources of water that are potentially useful.
- 4. Out of total volume of water on earth; 97.5% exists in oceans and seas. About 2.5% of total water is available as freshwater. 70% of total freshwater is present as frozen ice in icebergs and glaciers. A little less than 30% of total freshwater is stored as groundwater. India receives about 4% of global precipitation. India ranks 133rd in the world in terms of water availability per person per annum. The total renewable water resources in India are estimated at 1,897 sq km per annum. It is predicted that large parts of India will join regions with absolute water scarcity; by 2025.
- 5. Overexploitation of water: excessive use and unequal access to water among different social groups are the main causes of water scarcity. More Demand: A large population needs ever more water for various purposes. Large scale farming also needs lot of water for irrigation. While demand has been increasing, the process of natural recharge of groundwater has suffered because of several reasons.
- 6. Reduced Recharge of Groundwater: Large scale deforestation has disturbed the natural recharge of groundwater at many places. Construction of concrete buildings, factories and roads has also made the ground less impervious to rainwater. This has almost totally stopped the percolation of rainwater to recharge groundwater. Contamination: Excess use of chemical fertilisers and insecticides has contaminated groundwater at many places. The contamination is at such a high level that water has become unfit for human consumption. Sewage and effluents are being discharged into rivers and ponds; without being treated. This has turned most of the rivers into filthy drains.
- 7. India has had a long tradition of building various structures to manage water resources. Irrigation systems were built as early as during the Mauryan Empire. Benefits of Dams: At present, many multipurpose dam projects have been built in India. These dams serve many purposes. They prevent flood by checking the flow of water. The water from the dams is used through a system of canals to irrigate far flung areas. Dams are also used for electricity generation. Moreover, drinking water is also supplied from the dams.
- 8. Water Resource Management Harms of Dams: But dams have caused large scale displacement of people. Additionally, a vast tract of land gets submerged in the catchment area of dam. This results in large scale environmental consequences. Due to these reasons, many movement groups have begun protesting against building of large dams. Narmada Bachao Andolan is an example of such movements.
- 9. Rainwater Harvesting Most of the rainwater just flows off without percolating down the ground. This can be prevented by using rainwater harvesting. Rainwater can be collected for future use or can be channelized to recharge groundwater. Rooftop rainwater harvesting is ideal to be applied at small scale. Many infrastructure projects; like Metro rail and flyovers have also started making provisions for rainwater harvesting. Some traditional examples of rainwater harvesting structures are: kuls in Himachal, tankas and khadins in Rajasthan, ahir and pynes in Bihar, etc.
- 10. Water Resources How rainwater harvesting in semi-arid regions of Rajasthan is carried out. Almost all the houses in the semi arid regions of Rajasthan have traditionally underground constructed tanks or tanks for storing drinking water. They are as large as a big room and are a part of the well developed rooftop rainwater harvesting system. These tanks are constructed inside the main house or the courtyard, and are connected to the sloping roofs of the houses through a pipe.
- 11. Water Resources How rainwater harvesting in semi-arid regions of Rajasthan is carried out. The rain falling on the rooftop travels down and is stored in the tanks. The first spell of rain is not collected as this water cleans the roof and the pipes. The rainwater from the subsequent spells is then collected. The rainwater can be stored in the tanks till the next rainfall making it and extremely reliable source of drinking water when all other sources are dried up, particularly in the summers. The tanks also help in cooling the houses as rooms built around them have generally low temperatures due to conduction
- 12. Water Resources How modern adaptations of traditional rainwater harvesting methods are being carried out to conserve and store water. Traditional methods of rainwater harvesting like ‘the rooftop method’ are becoming popular in India. In Gendathur village, Mysore, about 200 households have adopted the rooftop rainwater harvesting method, thereby making the village rich in rainwater. The state of Tamil Nadu has made it compulsory for all the houses to have rooftop rainwater harvesting structures. Defaulters are severely punished.
- 13. Water Resources The modern rainwater harvesting is done as; a. Rooftop rain water is collected using a PVC pipe. b. It is filtered using sand and bricks. c. It is filtered using sand and bricks. d. Underground pipe takes this water to sump for immediate usage. e. Excess water from the sumps is taken to the well. f. Water from the well recharges the underground. g. Later this water is taken out from the well during summer or dry season
- 14. Thank You