Water Resources

Topics to be covered -

1. Water

2. Fresh water.

3. Water scarcity

4. Causes and types.

5. Dams

6. Advantages and disadvantage

7. Rainwater harvesting

8. Old and modern methods

Water

Three-fourth of the earth’s surface is covered with water but only a small proportion of it accounts for freshwater, that can be put to use. Water is a renewable resource.

Fresh water:

96.5 per cent of the total volume of world’s water is estimated to exist as oceans and only 2.5 per cent exists as fresh water. 70 per cent of the fresh water occurs as ice sheets and glaciers in Antarctica, Greenland and the mountainous regions of the world. Less than 30 per cent is stored as groundwater in the world’s acquirers. Fresh water is mainly obtained from surface run off and ground water. This is continually being renewed and recharged through the hydrological cycle. All the water moves within the hydrological cycle making water a renewable resource.

Three fresh water sources are:

Precipitation—from rainfall; Surface water—in rivers, lakes, etc.; Ground water—water stored in underground acquirers which gets recharged by rainfall.

Water Scarcity and the Need for Water Conservation and Management

The availability of water resources varies over space and time so comes the term Water scarcity, 

Which means shortage of water. It is usually associated with regions having low rainfall or drought prone areas.

Causes -

There are many other reasons which lead to scarcity of water:

Large growing population; In the agricultural sector, water resources are being over-exploited to expand irrigated areas and dry- season agriculture; More water required for irrigation purposes to facilitate higher food production, i. e., for doing multiple cropping and for HYV seeds; There is greater demand for water with growing urbanization and industrialization; An unequal access to water among different social groups; The quality of water is deteriorating, i.e., getting polluted by domestic and industrial wastes, chemical fertilizers and pesticides used in agriculture; Excessive use of water by industries which also require water to generate hydro-electric power to run them; and Over exploitation of water in the urban areas.

Water scarcity is caused by over-exploitation, excessive use and unequal access to water among different social groups.

Water resources are being over-exploited to expand irrigated areas for dry-season agriculture.

In some areas, water is sufficiently available to meet the needs of the people. But, those areas still suffer from water scarcity due to bad quality of water.

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.

•To prevent degradation of our natural ecosystems.

Adverse effects of over-exploitation of ground water resources:

Pumping out more water from under the ground may lead to falling ground water levels.

It will adversely affect water availability.

This, in turn, will affect our agriculture and food security of the people.

Impoverishment of water resources may adversely affect the ecological cycle.

Main causes of water pollution:

Domestic wastes, especially urban sewers; industrial wastes are disposed off in the water without proper treatment; chemical effluents from industries and from agricultural sector; and many human activities, e.g., religious rituals and immersing of idols, etc. in the water also pollute water.

Measures for water conservation:

Do not overdraw the ground water, recharge it by techniques like rainwater harvesting; tapping rainwater in reservoirs, watershed development programmes, etc.

Avoid wastage of water at all levels and do not pollute the water.

Adopting water conserving techniques of irrigation, e.g., drip irrigation and sprinklers etc., especially in dry areas.

Multi-Purpose River Projects and Integrated Water Resources Management -

In ancient times, we used to conserve water by constructing sophisticated hydraulic structures like dams built of stone rubble, reservoirs or lakes, embankments and canals for irrigation. We have continued this tradition in modern India by building dams in most of our river basins.

 Dams-

A dam is a barrier across flowing water that obstructs, directs or retards the flow, often creating a reservoir, lake or impoundment. “Dam” refers to the reservoir rather than the structure.

Dams are built:

•To impound rivers and rainwater that can be used later to irrigate agricultural fields.

•For electricity generation.

•Water supply for domestic and industrial uses.

•Flood control.

•Recreation, inland navigation and fish breeding.

Side effects of Creating Dams

•Regulating and damming of rivers affect their natural flow.

•Poorer the habitats for the rivers’ aquatic life.

•Fragment rivers make it difficult for aquatic fauna to migrate.

•Dams created on the floodplains submerge the existing vegetation and soil leading to its decomposition over a period of time.

•Creating of large dams has been the cause of many new environmental movements like the ‘Narmada Bachao Andolan’ and the ‘Tehri Dam Andolan’ etc.

•Many times local people had to give up their land, livelihood and their control over resources for the construction of the dam.

•Most of the objections to the projects arose due to their failure to achieve the purposes for which they were built. 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.

Have a look at the India Major Rivers and Dams in the map below:

Dams- and conflicts -

1. Narmada Bachao Andolan’:

Narmada Bachao Andolan or Save Narmada Movement is an NGO that mobilized tribal people, farmers, environmentalists and human rights activists against the Sardar Sarovar Dam being built across the Narmada river in Gujarat. The movement originally focused on environmental issues related to submerging of trees under the dam water. Recently its aim has been to enable the displaced poor people to get full rehabilitation facilities from the government.

2. Tehri dam Andolan

3. Kaveri Dispute

4. Mahanadi Dispute 

Rain Water Harvesting

Rainwater harvesting is a simple method by which rainfall is collected for future usage. The collected rainwater may be stored, utilised in different ways or directly used for recharge purposes.

Different methods have been adopted in different areas for Rain Water Harvesting.

Traditional methods -

•In hill and mountainous regions, people have built diversion channels like the ‘guls’ or ‘kuls’ of the Western Himalayas for agriculture.

•“Rooftop rainwater harvesting” is 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 such as ‘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 have 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.