Introduction:
Freshwater can be obtained directly from precipitation, surface run off and groundwater that is continuously being renewed and recharged through the hydrological cycle.
All water moves within the hydrological cycle ensuring that water is a renewable resource.
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.
Water scarcity and the need for water conservation and management:
When we speak of water shortages, we immediately associate it with regions having low rainfall or those that are drought prone.
True, the availability of water resources varies over space and time, mainly due to the variations in seasonal and annual precipitation, but water scarcity in most cases is caused by over exploitation, excessive use and unequal access to water among different social groups
Causes of water scarcity:
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.
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:
Sewage and effluents are being discharged into rivers and ponds; without being treated.
This has turned most of the rivers into filthy drains.
Quantitative aspects of water scarcity:
Water scarcity may be an outcome of large and growing population and consequent greater demands for water, and unequal access to it.
To facilitate higher food grain production, water resources are being over-exploited to expand irrigated areas and dry season agriculture.
Most farmers have their own wells and tube-wells in their farms for irrigation to increase their produce.
It may lead to falling groundwater levels, adversely affecting water availability and food security of the people.
The ever increasing number of industries has made matters worse by exerting pressure on existing freshwater resources.
Industries, apart from being heavy users of water, also require power to run them.
Much of this energy comes from hydroelectric power.
Today, in India hydroelectric power contributes approximately 22 per cent of the total electricity produced.
Multiplying urban centres with large and dense populations and urban lifestyles have not only added to water and energy requirements but have further aggravated the problem.
Most housing societies or colonies in the cities have their own groundwater pumping devices to meet their water needs, thus fragile water resources are being over exploited and have caused their depletion in several of these cities.
Qualitative aspects of water scarcity:
In many areas water is sufficiently available to meet the needs of the people, but, the area still suffers from water scarcity.
This scarcity may be due to bad quality of water.
Even if there is ample water to meet the needs of the people, much of it may be polluted by domestic and industrial wastes, chemicals, pesticides and fertilisers used in agriculture, thus, making it hazardous for human use
Need to conserve and manage our water resources:
The need of the hour is to conserve and manage our water resources, to safeguard ourselves from health hazards, to ensure food security, continuation of our livelihoods and productive activities and also to prevent degradation of our natural ecosystems.
Over exploitation and mismanagement of water resources will impoverish this resource and cause ecological crisis that may have profound impact on our lives.
India’s rivers, especially the smaller ones, have all turned into toxic streams.
And even the big ones like the Ganga and Yamuna are far from being pure.
The assault on India’s rivers – from population growth, agricultural modernisation, urbanisation and industrialisation – is enormous and growing by the day….. This entire life stands threatened.
Multi-purpose river projects and integrated water resources management:
Archaeological and historical records show that from ancient times we have been constructing sophisticated hydraulic structures like dams built of stone Prava rubble, reservoirs or lakes, embankments and canals for irrigation
Dam – A barrier constructed to hold back water and raise its level, forming a reservoir used to generate electricity or as a water supply is called dam.
Multipurpose projects – A type of project which fulfils a variety of purposes at the same time is called multipurpose projects. Ex– irrigation, generation of electricity, flood control, fish breeding, soil conservation, etc.
Hydraulic structures in Ancient India:
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 (Karnataka), 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.
Multi-purpose projects – ‘temples of modern India’:
Multipurpose projects, launched after Independence with their integrated water resources management approach, were thought of as the vehicle that would lead the nation to development and progress, overcoming the handicap of its colonial past.
Jawaharlal Nehru proudly proclaimed the dams as the temples of modem India’; the reason being that it would integrate development of agriculture and the village economy with rapid industrialization and growth of the urban economy.
Dams were traditionally built to impound rivers and rainwater that could be used later to irrigate agricultural fields.
Today, dams are built not just for irrigation but for electricity generation, water supply for domestic and industrial uses, flood control, recreation, inland navigation and fish breeding.
Hence, dams are now referred to as multipurpose projects where the many uses of the impounded water are integrated with one another.
For example, in the Satluj Beas river basin, the Bhakra Nangal project water Peri is being used both for hydel power production and irrigation.
Similarly, the Hirakud project in the Mahanadi basin integrates conservation of water with flood control.
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 submerge the existing vegetation and soil leading to its decomposition over a period of time.
Dams have also been the cause of many new social movements like the Narmada Bachao Andolan’ and the Tehri Dam Andolan’ etc.
Resistance to these projects has primarily been due to the large-scale displacement of local communities.
Irrigation has also changed the cropping patter of many regions with farmers shifting to water intensive and commercial crops.
This has great ecological consequences like salinisation of the soil.
It has transformed the social landscape i.e. increasing the social gap between the richer landowners and the landless poor.
Inter-state water disputes are also becoming common with regard to sharing the costs and benefits of the multi-purpose project.
Objections to the projects:
Their failure to achieve the purposes for which they were built.
Ironically, the dams that were constructed to control floods have triggered floods due to sedimentation in the reservoir.
The Big dams have mostly been unsuccessful in controlling floods at the time of excessive rainfall.
The floods have not only devastated life and properly but also caused extensive soil erosion.
Sedimentation also meant that the flood plains were deprived of silt, natural fertilizers, further adding on to the problem of land degradation.
Multi-purpose projects induced earthquakes, caused water-borne diseases and pests and pollution resulting from excessive use of water.
Narmada Bachao Andolan or Save Narmada Movement is a Non Governmental Organisation (NGO) that mobilised tribal people, farmers, environmentalists and human rights activists against the Sardar Sarovar Dam being built across the Narmada River in Gujarat.
It originally focused on the environmental issues related to trees that would be submerged under the dam water.
Recently it has re-focused the aim to enable poor citizens, especially the oustees (displaced people) to get full rehabilitation facilities from the government.
People felt that their suffering would not be in vain… accepted the trauma of displacement believing in the promise of irrigated fields and plentiful harvests.
So, often the survivors of Rihand told us that they accepted their sufferings as sacrifice for the sake of their nation.
But now, after thirty bitter years of being adrift, their livelihood having even being more precarious, they keep asking: “Are we the only ones chosen to make sacrifices for the nation?”
Do you know?
Sardar Sarovar Dam has been built over the Narmada River in Gujarat.
This is one of the largest water resource projects of India covering four states – Maharashtra, Madhya Pradesh, Gujarat and Rajasthan.
The Sardar Sarovar project would meet the requirement of water in drought-prone and desert areas of Gujarat (9,490 villages and 173 towns) and Rajasthan (124 villages).
Do you know?
Do you know that the Krishna-Godavari dispute is due to the objections raised by Karnataka and Andhra Pradesh governments?
It is regarding the diversion of more water at Koyna by the Maharashtra government for a multipurpose project.
This would reduce downstream flow in their states with adverse consequences for agriculture and industry.
Major River Projects:
|
Major River Projects
|
|
River Projects
|
Rivers
|
|
Salal Project
|
Chenab
|
|
Bhakra Nangal
|
Satluj
|
|
Tehri
|
Bhagirathi (Ganga)
|
|
Naraora
|
Ganga
|
|
Gandhi Sagar
|
Chambal
|
|
Kota Rarrage
|
Chambal
|
|
Sardar Sarovar
|
Narmada
|
|
Pravara
|
Paravara (Godavari)
|
|
Koyna
|
Krishna
|
|
Nagarjuna Sagar
|
Krishna
|
|
Tungabhadra
|
Tungabhadra (Krishna)
|
|
Mettur
|
Kaveri
|
|
Krishna Raj Sagar
|
Kaveri
|
|
Periyar
|
Kaveri
|
|
Hirakud
|
Mahanadi
|
|
Tilay, Konar, Maithon and Panchet
|
Damodar (D.V.C.)
|
Do you know?
Hirakud Dam is built across the Mahanadi River, about 15 km from Sambalpur in the state of Orissa in India. Built in 1957, the dam is one of the world’s longest earthen dams. Hirakud Dam is the longest man mode dam in the world, about 16 mi (26 km) in length.
The Tehri Dam is a multi-purpose rock and earth-fill embankment da on the Bhagirathi River near Tehri in Uttarakhand, India. It is the primar dam of the Tehri Hydro Development Corporation Ltd.
Do you know that the Krishna Godavari dispute is due to the objections raised by Karnataka and Andhra Pradesh governments? It is regarding the diversion of more water at Koyna by the Maharashtra government for a multipurpose project. This would reduce downstream flow in their states with adverse consequences for agriculture and industry.
Rainwater harvesting – A technique of collection and storage of rain water in surface (storage tanks) or sub surface aquifer before it is lost as surface runoff is called Rainwater harvesting.
Water harvesting system, a viable alternative, both socio – economically and environmentally.
Water-harvesting system in ancient India:
People had in-depth knowledge of rainfall regimes and soil type’s and developed wide ranging techniques to harvest rainwater, groundwater, river water and flood water in keeping with the local ecological conditions and their water needs.
In hill and mountainous regions, people built diversion channels like the guls’ or ‘kuls’ of the Western Himalayas for agriculture.
Rooftop rain water harvesting’ was commonly practised to store drinking 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.
Rooftop rainwater harvesting as practised in Rajasthan:
In the semi-arid and arid regions of Rajasthan, particularly in Bikaner,Phalodi and Barmer, almost all the houses traditionally had underground tanks or tankas for storing drinking water.
The tanks could be as large as a big room.
The tankas were part of the well-developed rooftop rainwater harvesting system and were built inside the main house or the courtyard.
They were connected to the sloping roofs of the houses through a pipe.
Rain falling on the rooftops would travel down the pipe and was stored in these underground ‘tankas.
The first spell of rain was usually not collected as this would clean the roofs and the pipes.
The rainwater from the subsequent showers was collected.
The rainwater can be stored in the tankas till the next rainfall making it an extremely reliable source of drinking water when all other sources are dried up, particularly in the summers.
Rainwater, or palar pani, as commonly referred to in these parts, is considered the purest form of natural water.
Many houses constructed underground rooms adjoining the ‘tanka’ to beat the summer heat as it would keep the room cool.
Interesting facts:
Rooftop rainwater 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 rooftop rainwater harvesting structure.
Nearly 15-25 per cent of the total water requirement of the household comes from rooftop water harvesting.
Rooftop harvesting was common across the towns and villages of the Thar.
Rainwater that falls on the sloping roofs of houses is taken through a pipe into an underground tanka (circular holes in the ground) built in the main house or in the courtyard.
The picture above shows water being taken from a neighbour’s roof through a long pipe.
Here the neighbour’s rooftop has been used for collection of rainwater.
The picture shows a hole through which rainwater flows down into an underground tanka.
Modern adaptations of traditional Rainwater harvesting methods:
In many parts of rural and urban India, rooftop rainwater harvesting is being successfully adapted to store and conserve water.
In Gendathur, a remote backward village in Mysore, Kamataka, villagers has installed, in their household’s rooftop, rainwater harvesting system to meet their water needs.
Nearly 200 households have installed this system and the village has earned the rare distinction of being rich in rainwater.
Gendathur receives an annual precipitation of 1,000 mm, and with 80 per cent of collection efficiency and of about 10 fillings, every house can collect and use about 50,000 litres of water annually.
From the 20 houses, the net amount of rainwater harvested annually amounts to 1, 00,000 litres.
Interesting facts:
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.
Bamboo drip irrigation system:
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.
