UPSC Geography Drainage NCERT Extracts - Water Resources in India

Water Resources

• Water is a cyclic resource with abundant supplies on the globe.
• Apprpxmiately, 71 percent of the earth's surface is covered with it but fresh water constitutes only about 3 per cent of the total water.
• In Intact, a very small proportion of fresh water is effectively available for human use.
• India accounts for about 2.45 per cent of world's surface area, 4 per cent of the world's water resources and about 16 per cent of world's population.       
• The total water available from precipitation in the country in a year is about 4,000 cubic km.
• The .availability from surface water and replenishable groundwater is 1,869 cubic km. Out of this only 60 per cent can be put to beneficial uses.
• Thus, the total utilisable water resource in the country is only 1,122 cubic km.
• There are four major sources of surface water. These are rivers, lakes, ponds, and tanks.
• In the country, there are about 10,360 rivers and their tributaries longer than 1.6 km each.
• The mean annual flow in all the river basins in India is estimated to be 1,869 cubic km.
• The total replenishable groundwater resources in the country are about 432 cubic km.
• The Ganga and the Brahamaputra basins, have about 46 per cent of the total replenishable groundwater resources.
• The level of groundwater utilisation is relatively high in the river basins lying in north- western region and parts of south India.
• The groundwater utilisation is very high in the states of Punjab, Haryana, Rajasthan, and Tamil Nadu.
• However, there are States like Chhattisgarh, Odisha, Kerala, etc., which utilise only a small proportion of their groundwater potentials.
• States like Gujarat, Uttar Pradesh, Bihar, Tripura and Maharashtra are utilising their ground water resources at a moderate rate.
• India has a vast coastline and the coast is very indented in some states. Due to this, a number of lagoons and lakes have formed.
• The States like Kerala, Odisha and West Bengal have vast surface water resources in these lagoons and lakes.
• Although, water is generally brackish in these water-bodies, it is used for fishing and irrigating certain varieties of paddy crops, coconut, etc.
• In fact, India's water demand at present is dominated by irrigational needs.
• Agriculture accounts for most of the surface and ground water utilisation, it accounts for 89 per cent of the surface water and 92 per cent of the groundwater utilisation.
• While the share of industrial sector is limited to 2 per cent of the surface water utilization and 5 per cent of the ground-water, the share of domestic sector is higher (9 per cent) in surface water utilisation as compared to groundwater.
• The share of agricultural sector in total water utilisation is much higher than other sectors.
• However, in future, with development, the shares of industrial and domestic sectors in the country are likely to increase.
• The Yamuna river is the most polluted river in the country between Delhi and Etawah.
• Other severely polluted rivers are: the Sabarmati at Ahmedabad, the Gomti at Lucknow, the Kali, the Adyar, the Cooum (entire stretches), the Vaigai at Madurai and the Musi of Hyderabad and the Ganga at Kanpur and Varanasi.
• Groundwater pollution has occurred due to high concentrations of heavy/toxic metals, fluoride and nitrates at different parts of the country.
• The legislative provisions such as the Water (Prevention and Control of Pollution) Act, 1974, and Environment Protection Act, 1986 have not been implemented effectively.
• Thercsult is that in 1997, 251 polluting industries were located along the rivers and lakes.
• The Water Cess Act, 1977, meant to reduce pollution has also made marginal impacts.
• The Central and State Governments have initiated many watershed development and management programmes in the country.
• Haryali is a watershed development project sponsored by the Central Government which aims at enabling the rural population to conserve water for drinking, irrigation, fisheries and afforestation.
• The Project is being executed by Gram Panchayats with people's participation.
• Neeru-Meeru (Water and You) programme (in Andhra Pradesh) and Arvary Pani Sansad (in Alwar, Rajasthan) have taken up constructions of various water-harvesting structures such as percolation tanks, dug out ponds (Johad), check dams, etc. through people's participation.
• Tamil Nadu has made water harvesting structures in the houses compulsory. No building can be constructed without making structures for water harvesting.

Rainwater Harvesting

• Rain water harvesting is a method to capture and store rainwater for various uses.
• It is also used to recharge groundwater aquifers. It is a low cost and eco-friendly technique for preserving every drop of water by guiding the rain water to bore well, pits and wells.
• Rainwater harvesting increases water availability, checks the declining ground water table, improves the quality of groundwater through dilution of contaminants like fluoride and nitrates, prevents soil erosion, and flooding and arrests salt water intrusion in coastal areas if used to recharge aquifers.
• Rainwater harvesting has been practised through various methods by different communities in the country for a long time.
• Traditional rain water harvesting in rural areas is done by using surface storage bodies like lakes, ponds, irrigation tanks, etc.
• In Rajasthan, rainwater harvesting structures locally known as Kund or Tanka (a covered underground tank) are constructed near or in the house or village to store harvested rainwater.

Highlights of India's National Water Policy, 2002

• The National Water Policy, 2002 stipulates water allocation priorities broadly in the following order : drinking water; irrigation, hydro-power, navigation, industria T and other uses.
• The policy stipulates progressive new approaches to water management.
• Key features include :
• Irrigation and multi-purpose projects should invariably include drinking water component, wherever there is no alternative source of drinking water.
• Providing drinking water to all human beings and animals should be the first priority.
• Measures should be taken to limit arid regulate the exploitation of groundwater.
• Both surface and groundwater should be regularly monitored for quality. A phased programme should be undertaken for improving water quality.
• The efficiency of utilisation in all the diverse uses of water should be improved.
• Awareness of water as a scarce resource should be fostered.
• Conservation consciousness should be promoted through education, regulation, incentives and disincentives.

Some Important Facts

• Salinity is the amount of salt in grams present in 1,000 grams of water. The average Salinity of the oceans is imparts per thousand.
• Dead sea in Israel has salinity of 340 grams per litre of water. Swimmers can float in it because the increased salt content makes it dense.
• March is celebrated as World Water Day when the need to conserve water is reinforced in different ways.
• Waves are formed when winds scrape across the ocean surface. The stronger the wind blows, me bigger the wave becomes.
• Tsunami is a Japanese word that means "Harbour waves" as the harbours get destroyed whenever there is tsunami. Tsunami or die harbour wave struck havoc in the Indian Ocean on the 26 December, 2004. The wave -was the result of the earthquake that had its epicenter close to the western boundary of Sumatra. The magnitude of the earthquake was 9.0 on the Richter
• Tsimami travelled at a speed of about 800 km. per hour, comparable to speed of commercial aircraft and completely washed away some of the islands in the Indianocean.
• The Indira point in the Andaman and Nicobar islands that marked the southernmost point of India got completely submerged.
• While the earthquake cannot be predicted in advance, it is possible to give a three-hour notice of a potential tsunami. Tsunamis are rare in the Indian Ocean as the seismic activity is less as compared to the Pacific,
• The first indication that tsunami is approaching is the rapid withdrawal of water from the coastal region, followed by destructive wave.
• The rhythmic rise and fall of ocean water twice m a day is called a tide. It is high tide when water covers much of the shore by rising to its highest level. It is low tide when water falls to its lowest level and recedes from the shore.
• The strong gravitational pull exerted by the sun and the moon on the earth's surface causes the tides. The water of the earth closer to the moon gets pulled under the influence of the moon's gravitational force and causes high tide.
• During the full moon and new moon days, the sun, the moon and the earth are in the same line and the tides are highest. These tides are called spring tides.
• But when the moon is in its first and last quarter, the ocean waters get drawn in diagonally opposite directions by the gravitational pull of sun and earth resulting in low tides. These tides are called neap tides.
• High tides help in navigation. They raise the water level close to the shores. This helps the ships to arrive at the harbour more easily. The high tides also help in fishing.
• Many more fish come closer to the shore during the high tide. This enables fishermen to get a plentiful catch. The rise and fall of water due to tides is being used to generate electricity in some places.
• 5 per cent of the total volume of world's water is estimated to exist as oceans and only 2.5 per cent as freshwater.
• Nearly 70 per cent of this freshwater occurs as ice sheets and glaciers in Antarctica, Greenland and the mountainous regions of the world, while a little less than 30 per cent is stored as groundwater in the world's aquifers.
• In the first century B.C., Sringaverapura near Allahabad had sophisticated water harvesting system channelling the flood water of the river Ganga.
• During the time of Chandragupta Maurya, dams, lakes and irrigation systems were extensively built.
• Evidences of sophisticated irrigation works have also been found in Kalinga, (Odisha), Nagarjunakonda (Andhra Pradesh), Bennur (Kamataka), Kolhapur (Maharashtra), etc.
• In the 11th Century, Bhopal Lake, one of the largest artificial lakes of its time was built.
• In the 14th Century, the tank in Hauz Khas, Delhi was constructed by Iltutmish for supplying water to Siri Fort area.
• A dam is a barrier across flowing water that obstructs, directs or retards the flow, often creating a reservoir, lake or impoundment.
• Jawaharlal Nehru proudly proclaimed the dams as the 'temples of modern India'; the reason being that it would integrate development of agriculture and the village economy with rapid industrialisation and growth of the urban economy.
• In recent years, multi-purpose projects and large dams have come under great scrutiny and opposition for a variety of reasons.
• Regulating and 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 the rivers' aquatic life.
• Dams also fragment rivers making it difficult for aquatic fauna to migrate, especially for spawning.
• The reservoirs that are created on the floodplains also submerge the existing vegetation and soil leading to its decomposition over a period of time.
• Resistance to these projects has primarily been due to the large-scale displacement of local communities.
• Ironically, the dams that were constructed to control floods have triggered floods due to sedimentation in the reservoir. Moreover, the big dams have mostly been unsuccessful in controlling floods at the time of excessive rainfall.
• Sedimentation also meant that the flood plains were deprived of silt, a natural fertiliser, further adding on to the problem of land degradation.
• It was also observed? mat the multi-purpose projects induced earthquakes, caused waterbome diseases and pests and pollution resulting from excessive use of water.
• Roof tap nun water harvesting is the most common practice in Shillong, Meghalaya.
• It is interesting because Cherapunjee and Mawsynram situated at a distance of 55 km from Shillong receive the highest rainfall in the world, yet the state capital Shillong faces acute shortage of water.
• Nearly every household in the city has a roof top rain water harvesting structure. Nearly 15-25 per cent of the total water requirement of the household comes from roof top water harvesting
• In Meghalaya, a 200-year-old system of tapping stream and spring water by using bamboo pipes, is prevalent. About 18-20 litres of water enters the bamboo pipe system, gets transported over hundreds of metres, and finally reduces to 20-80 drops per minute at the site of the plant.