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Water resources

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Water resources

  2. 2. Three - fourth of the earth surface is covered with water but only less percentage of it is accounted by freshwater. This freshwater can be mainly obtained by precipitation, surface run off and ground water that is continually being renewed and recharged through the hydrological cycle ensuring that water is a renewable resource. The shortage of water as compared to its demand is known as water scarcity. • Causes of water scarcity Quantitative aspects 1. Variation in seasonal and annual precipitation 2. Over exploitation of water resources
  3. 3. 3. Excessive use of water 4. Unequal access to water among different social groups. Qualitative aspects 1. Bad quality of water. 2. Population growth 3. Commercialisation of agriculture 4. Industrialisation 5. Urbanisation • Needs to conserve water resources  Water is necessary for life on earth. It is believed that life first originated in water before it invaded land. Water is in fact a pre-condition of life. Industrial waste in water
  4. 4.  Cultivation of crops depends on water. As India is a agricultural country, so availability of water is must.  Water is also essential for drinking and other domestic works.  It is also used in industries. • 96.5% of water is exist as oceans and 2.5% as freshwater. • Nearly 70% of the freshwater is in the form of ice sheets and glaciers, while a little less than 30% is stored as groundwater. • India receives 4% of global precipitation and ranks 133 in the world in terms of water availability per person per annum. • The total renewable water resources of India is estimated 1,897sq km per annum. • By 2025, large parts of India will join countries having absolute water scarcity.
  5. 5. Pandit Jawaharlal Nehru proclaimed the dams as “temples of modern India” as they were thought of as the vehicle that would lead the nation to development and progress. They would integrate development of agriculture and the village economy with rapid industrialization and growth of urban economy. What is a dam? Dam is a barrier across flowing water that obstructs, directs or retards the flow often creating a reservoir, lake or impoundment.
  6. 6. Multipurpose river projects Dams are considered as a multipurpose river project because they can be used for many purposes as: • irrigation • electricity generation • water supply for domestic and industrial uses • flood control • recreation • inland navigation • fish breeding Example : 1. Bhakra Nangal project in Satluj-Beas basin is used both for hydel power production and irrigation. 2. Hirakud project in Mahanadi basin integrates conservation of water by flood control.
  7. 7. Basedon structure and material used: • timber dams • embankment dams • masonry dams Basedon height: • low dams • medium height dams • high dams Classification of dams Dams can be classified based on their structure, intended purpose or height :
  8. 8. • Adverse effect on aquatic life: Regulating & damming of rivers affect their natural flow causing poor sediment flow and excessive sedimentation at the bottom of the reservoir , resulting in rockier stream beds and poorer habitats for river’s aquatic life. • Adverse effect on soil fertility: Due to dams, there are no annual floods in the rivers and so the soil of the downstream region do not nutrient rich silt which decreases the fertility of soil. • Displacement of local communities: The building of large dams results in displacement of local communities because the local people often give up their land and livelihood and their control over resources for greater food of the nation.
  9. 9. • Adverse impact on migration of aquatic life: Dams also fragment rivers making it difficult for the aquatic fauna to migrate, especially for spawning. • Change in cropping pattern: The multipurpose river projects are responsible for providing assured means of irrigation to farmers. Due to this, most of the farmers have changed the cropping pattern shifting to water intensive and commercial crops. This has led to salinisation of soil leading to ecological imbalance. • Cause of disputes: Dams created conflicts between people wanting different uses and benefits from the same water resources. Inter-state water disputes are also becoming common with regard to sharing the costs and benefits of the multi-purpose project.
  10. 10. • Water harvesting is a very cheap and affordable method of conservation of water. • Indian people have in-depth knowledge of rainfall regime and soil type. They have developed techniques to harvest rainwater groundwater and flood water in keeping with the local ecological conditions and their water needs. • Rainwater harvesting techniques are more environmental friendly as compared to multipurpose river projects. Water harvesting systems are considered a variable alternative both socially and environmentally in a country like India because :
  11. 11. In hill and mountainous regions , people built diversion channels like the “guls”, or “kuls” of the Western Himalayas for agriculture. Rooftop rainwater harvesting was commonly practised to store drinking water particularly in Rajasthan. In flood plains of Bengal, people built inundation channels to irrigate their fields.
  12. 12. In arid and semi-arid regions, agricultural fields were converted into rain fed storage structures that allowed the water to stagnant and moisten the soil like the “khadins” in Jaisalmer and the “johads” in other parts of Rajasthan. In the semi-arid and arid regions of Rajasthan almost all the houses had underground tanks or tankas for storing drinking water. Bamboo drip irrigation system is also being used in some states.
  13. 13. Rainwater harvesting by making tanks • In Rajasthan rainwater harvesting is carried out by making tanks or tankas which are connected to the sloping roofs of the houses. • Rain falling on the rooftop would travel down the pipe , and was stored in these tanks. • The first spell of rain is usually not collected, as this would clean the roofs and pipes. The rainwater from the subsequent showers are then collected. • Water is used immediately or else stored in wells which recharges the groundwater.
  14. 14. 1. Who proclaimed the dams as the temples of modern India? a. Mahatma Gandhi b. Jawaharlal Nehru c. Indira Gandhi d. Dr. A.P.J Abdul Kalam 2. What are the underground tanks for storing drinking water? a. Kul b. Canal c. Tankas d. PVC Pipes
  15. 15. 3. Sardar Sarovar Project is based in the state of: a. Gujarat b. Madhya Pradesh c. Rajasthan d. Maharashtra 4. The Koyna Dam is being constructed on the river : a. Kaveri b. Yamuna c. Bhagirathi d. Krishna 5. Tanka is water harvesting technique associated with which of the following states: a. Tamil Nadu b. West Himalayas c. Gujarat d. Rajasthan
  16. 16. 6. Bhakra Nangal multipurpose project is constructed on the river: a. Satluj b. Mahanadi c. Ganga d. Chenab 7. In which of the following states people developed inundation channels to irrigate their fields? a. Rajasthan b. West Bengal c. Punjab d. Haryana Answers 1. (b) 5. (d) 2. (c) 6. (a) 3. (a) 7. (b) 4. (d)
  17. 17. 1. How is freshwater obtained? 2. How is freshwater being renewed? 3. Mention any two regions which are expected to face water shortage? 4. What is a dam? 5. What are multipurpose projects? 6. What is the need of rainwater harvesting? 7. What is water scarcity? Mention the responsible factors. 8. Name any two social movements which have been launched against multipurpose river projects. 9. How do people harvest water in the flood plains of Bengal? 10. What was the main purpose of launching multi-purpose project in India after independence?