Water resources

Water resources

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Water is the most valuable resources of nature. The distribution of water resource is highly uneven in India. It varies from about 20 Cm in Jaisalmer (Rajasthan) to over 1000 Cm at Mawsinram (Meghalaya).

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• India has 4 percent water whereas she is housing 16 percent of the world’s population
• India holds the top position globally in irrigated area.
• About one-eighth of the country is susceptible to floods, while one-sixth is drought-prone.
• Only 2.5% of the world's water is fresh, and the remaining 96.5% is in oceans.
• Ice sheets, glaciers in Antarctica, Greenland, and mountainous regions contain approximately 70% of freshwater, and the rest 30% is stored in the world's aquifers.

Sources of water

(A) Surface water

• There are four major sources of surface water. These are rivers, lakes, ponds and tanks
• Approximately 66% of the surface water in the country flows into the three major rivers: Indus, Ganges, and Brahmaputra.
• The Ganges basin has the highest storage capacity of usable water.
• Despite the maximum annual flow, the Brahmaputra basin has the least storage capacity of usable water.

Catchment area- Ganga> Godavari> Krishna

Utilizable surface water Resources- Ganga>Godavari> Indus

• If storage capacity of usable water is seen in terms of ratio, then Tapi river basin is 97 percent.

(B) Underground water-

• Underground water is formed when rainwater seeps into the earth's surface.
• In Rajasthan, where there is less rainfall, underground water is available at greater depths.
• In the north-eastern regions of India, the land is sloping, and water percolation is not suitable despite more rainfall.
• The Ganga-Brahmaputra plains and coastal plains have abundant underground water resources.

Water budget

• Water Budget means – the balance between the available water in the country and the water under use

Water Conservation

• Water conservation refers to the use of different methods and technique to conserve the water resources  

Different methods of water conservation

1.Conservation of rain water

Contour farming

• It is an example of such harvesting technique involving water and moisture control at a very simple level. 
• It often consists of rows of rocks placed along the contour of steps. Runoff captured by these barriers also allows for retention of soil, thereby serving as erosion control measure on gentle slopes. 
• This technique is especially suitable for areas having rainfall of considerable intensity, spread over large part i.e. in Himalayan area, north east states and Andaman and Nicobar islands.

Rain-water Harvesting-

• Rain Water 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
• Roof top rain water is collected using a PVC pipe & Filtered using sand and bricks

2.Ground water conservation

(i) Artificial recharge

• There are several techniques for artificial development and management of groundwater.
• One such method involves spreading water over the ground to increase the surface area and time for water to come in contact with soil.
• This technique maximizes the opportunity for water to seep into the ground.

(ii) Percolation tank method

• Percolation tanks are constructed across the water course for artificial recharge.

3.Catchment area protection (CAP)

• Catchment protection plans are also known as watershed protection or management plans.
• They aim to withhold runoff water by constructing a check bund across streams in hilly terrains.
• This delay in run-off allows for more time for water to seep underground.
• These methods are used in the north-east states and in hilly areas of tribal belts.
• Catchment protection plans also aid in soil conservation.
• Afforestation in the catchment area is another technique adopted for water and soil conservation.

4.Inter-basin transfer of water

• The western and peninsular regions have a low ratio of water resources to cultivable land.
• The northern and eastern regions, which are drained by Ganga and Brahmaputra, have significant water resources.
• Therefore, adopting a scheme to divert water from regions with surplus water to water-deficit regions can be beneficial.

5.Adoption of drip sprinkler irrigation

• Drip irrigation is an efficient irrigation method that involves watering a limited area around the plant using drips of water.
• This method is suitable for any area, but especially effective in areas with limited water supply.
• The sprinkler method is another effective method for irrigating water-scarce areas.

6.Management of growing pattern of crops

• Selection of area specific verities
• Maintaining Nutritional balance of the crop and agricultural land
• Using proper cover crop to maintain water availability in the soil

7.Reducing evapotranspiration

• Evapotranspiration losses can be reduced by reducing the evaporation from soil surface and transpiration from the plants, in arid zones, considerable amount of water is lost in evaporation from soil surface.
• This can be prevented by placing water tight moisture barriers or water tight mulches on the soil surface.
• Transpiration losses can be reduced by reducing air movement over a crop

8.Conservation of water in domestic use

• Reducing wastage-leaking pipes mean that lot of water never reaches to the people.
• Closing of taps while not in use.
• Better irrigation techniques – irrigation systems waste up to 70% water used. In drip irrigation water loss is significantly less.
• Use low flush toilets-reducing the amount of water used each time the lavatory is flushed.
• Build latrines and compact toilets which can turn human waste into clean, useful manurethis is much cheaper than connecting toilet to a piped sewage line.
• Greater use of recycled water ‘grey water’ in the home.

Grey water is defined as untreated household wastewater, which has not come into contact with toilet waste

9.Reuse of wastewater

• Proper reuse of waste water is also another method to conserve water resources

Some facts-

• Tamil Nadu has made rooftop rainwater harvesting compulsory for all houses in the state with legal provisions for punishment of defaulters.
• In the first century B.C., Sringaverapura near Allahabad had an advanced water harvesting system that channeled flood water from the river Ganga.
• During Chandragupta Maurya's time, dams, lakes, and irrigation systems were extensively constructed.
• In the 11th Century, Bhopal Lake, one of the largest artificial lakes of its time, was built.
• In the 14th Century, Iltutmish constructed the tank in Hauz Khas, Delhi, to supply water to the Siri Fort area.

Different water related projects and dams

1.Bhakra Nangal Project

• The Bhakra Nangal Project is a multi-purpose project built on the Satluj River.
• It consists of two dams - Bhakra and Nangal - and is named after them.
• The project is a joint venture of the Punjab, Haryana, and Rajasthan states.
• Its aim is to utilize the water resources of the Satluj River for the benefit of the involved states.
• The Bhakra Dam is one of the tallest straight gravity dams globally, and it has formed the Gobind Sagar Lake.

2.Tehri Dam

• This dam was conceived in 1949, situated at the confluence of the Bhagirathi and the Bhilangana rivers in Garwal district of Uttarakhand.
• This Tehri dam said to be the highest dam (with 2160.5 metere) in Asia was commissioned in 1972, but work on it began only in 1978.

3.The Damador Valley Project

• The Damodar River is a tributary of the Hugli River. It flows more or less in the west to east direction through Jharkhand and West Bengal. The Damodar River was termed river of sorrow.

4.The Narmada Valley Project

• The Narmada is the fifth largest river of India and the largest among the west flowing rivers of the peninsula, originating in the Amarkantak plateau of Madhya Pradesh. 
• The Narmada valley aims at harnessing this flow for the economic prosperity of the concerned area. 
• Narmada project designed to benefit the peoples of Gujarat, Madhya Pradesh, Maharashtra and Rajasthan tagged as a marginal beneficiary to get more drinking water.

5 Rihand Valley Project

• The Rihand Valley Project is a significant multipurpose project in Uttar Pradesh.
• It includes a straight gravity concrete dam that spans 934 meters in length and 92 meters in height, built across the Rihand River in the Mirzapur district of Uttar Pradesh.
• The reservoir formed by the Rihand dam is known as Govind Ballabh Pant Sagar.
• Additionally, a second dam has been built at Obra, situated 25 km north of the Rihand dam.

6.The Chambal Valley Project

• The Chambal Valley Project is a joint venture of Rajasthan and Madhya Pradesh, started in 1954 on the Chambal River.
• The project's primary objectives are to utilize the Chambal River for irrigation, generate power, and prevent/control soil erosion in the valley.
• The project has been implemented in three phases.

7.Polavaram Irrigation Project

• It is a multi-purpose irrigation project 
• It is located in Andhra Pradesh on the river Godavari, near Polavaram village and also spreads in parts of Chhattisgarh and Orissa
• It will facilitate an inter-basin transfer to the Krishna River basin through its Right canal.
• The Project has been accorded national project status by the union government in 2014 (under Section-90 of Andhra Pradesh Reorganization Act, 2014).