What is an aquifer?
Groundwater is the water that seeps through rocks and soil and is stored below the ground. The rocks in which ground water is stored are called aquifers. Aquifers are typically made up of gravel, sand, sandstone or limestone.
Why does India extract so much ground water?
India is the world’s largest user of groundwater, Since the 1980s the groundwater tables have been continuously dropping. Ninety percent of the groundwater extracted is used for irrigation that covers 60 percent of the total irrigated area. Of the extracted groundwater around 89% is used in the irrigation sector, 9% is used for the domestic purposes and the remainder 2% goes into industrial use. Groundwater also fulfils 50% of urban water requirements and 85% of rural domestic water requirements.
India’s groundwater use was just about 7 cubic kilometer in 1940; it went up to around 270 cubic kilometer by 2000. Since 1950, the total share of groundwater in irrigation has nearly doubled. The groundwater extraction rose sharply during the late 70s and 80s. Small and marginal farmers bored wells everywhere. Thus, today livelihood of 26 crore farmers and agricultural laborers crucially revolves around groundwater.
What are the major sources of irrigation in India?
Major means of irrigation in the country are canals, tanks and wells, including tube-wells. Of all these sources, groundwater contributes the largest share. Wells – dug wells, shallow tube-wells and deep tube wells – provide about 62% of water for irrigation, followed by canals with around 25%.
Why did the ground water source for irrigation gallop over the decades?
Over the years, there has been a steady rise in the groundwater utilisation for irrigation while other sources remained stagnated in the volume terms. Tube-well share has increased exponentially. There is a clear correlation in rise in groundwater use with the onset of the Green Revolution that demanded intensive use of inputs like water and fertilizers to boost crop production. Incentives such as credit for irrigation equipment and subsidies for electricity supply have further worsened the situation. Low power tariffs have led to excessive and wasteful water usage, leading to a sharp fall in water tables.
How do aquifers get recharged?
According to the 2016 Central Ground Water Board (CGWB) report, in the year ending January 2016 barely 3% well structures registered a rise in water level more than 4 metres, 35% showed lesser rise and 64% wells showed decline in water level. It is an alarming finding. The replenishment takes place through
1. Rainfall,
2. Back flows from irrigation and
3. Seepage from canals,
4. Recharge from tanks, ponds and water conservation structures etc.
The overall contribution of rainfall to the country’s annual groundwater resource is 68% and the rest comes from other resources as mentioned above.
What is the impact of overexploitation of ground water?
The over-exploitation of groundwater has created a series of problems, particularly in the agriculture-intensive belts across India. The situation is becoming particularly acute in the Northwest, where the groundwater levels have plunged from 8m to 16m below ground. As the levels fall, rising pumping costs ultimately makes extraction uneconomical; small formers and labourers get directly impacted. Food production declines and so will food security. There will be migration to towns and cities. The average farmer in Punjab, Rajasthan and Haryana faces the prospect of having no groundwater left for irrigation by 2025.
As climate change is altering the monsoon pattern, the stress on groundwater resources is likely to increase.
What is ground water development?
Ground water development is a ratio of the annual ground water extraction to the net annual ground water availability. It indicates the quantity of ground water available for use without making the depth of water fall to uneconomic levels and aquifers non-rechargeable. 0-70% is considered safe, 70-90% is semi-critical, 90-100% is critical, and over 100% is considered over-exploited.
In the states of Delhi, Haryana, Punjab and Rajasthan, the annual ground water consumption is more than annual ground water recharge. In the states of Himachal Pradesh, Tamil Nadu and Uttar Pradesh and the Union Territory of Puducherry, the level of ground water development is 70% or above.
How does ground water get polluted?
Ground water is considered contaminated when certain pollutants are present in excess of the limits prescribed for drinking water. The commonly observed contaminants include arsenic, fluoride, nitrate and iron, which are geogenic in nature. Geogenic contaminants are those that occur as a result of geological processes happening within the earth’s crust. Besides, there are other contaminants such as bacteria, phosphates and heavy metals resulting from human activities – from domestic sewage, agricultural practices and industrial effluents. The sources of contamination include pollution by landfills, septic tanks, leaky underground gas tanks, and from overuse of fertilizers and pesticides. It has been pointed out that nearly 60% of all districts in the country have issues related to either availability of ground water, or quality of ground water, or both.
Government studies have revealed high arsenic content in groundwater of 68 districts in 10 states – Haryana, Punjab, Uttar Pradesh, Bihar, Jharkhand, Chhattisgarh, West Bengal, Assam, Manipur and Karnataka.
What reforms can be made in agriculture for better water utilisation?
Since the 80s, roughly 84% of the total addition to the net irrigated area has come through groundwater, agriculture sector being the prime driver. Certain issues need urgent consideration:
1. Decisions of cropping intensity and pattern are taken largely independent of the status of groundwater availability in most areas.
2. Another factor was pin pointed by the High-Level Committee on restructuring of the Food Corporation of India in 2014, chaired by Mr. Shanta Kumar. It found that although Minimum Support Prices (MSPs) are currently announced for 23 crops, the effective price support is for wheat and rice. This creates highly skewed incentive structures in favour of wheat and paddy, which are water intensive crops and depend heavily on ground water for their growth.
3. Additionally, Indian agriculture is highly water inefficient. India irrigation system is highly wasteful; it uses almost twice the amount of water to grow crops as compared to China and United States.
4. The Committee also suggested that cropping pattern needed to be diversified by providing better price support for pulses and oilseeds. This would also incentivize the production of these food grains.
5. The practice of providing power subsidies for agriculture has played a major role in reckless use and over extraction of groundwater in India. Moreover, electricity supply is not metered and a flat tariff is charged depending on the horsepower of the pump. So some kind of regulation on the use of electricity is needed to avoid wastage of groundwater. Separate electric feeders for pumping ground water for agricultural use could address the issue.
6. For reducing dependence of agriculture on groundwater, other experts have suggested the use of demand management measures in agriculture. For example,
What is Gujarat scheme of ‘Jyotigram’?
It was a scheme which was launched during 2003-2006 by investing 1450 crore rupees. It involved separation of agricultural electricity feeders from non-agricultural ones and establishing a tight regime for farm power rationing in the rural Gujarat. By 2006, the state had covered almost all of its 18,000 villages under the scheme of rationalized power supply. Major benefits are:
What is the mandate of Central Ground Water Board (CGWB)?
It is a subordinate office of the Ministry of Jal Shakti Government of India, is the National Apex Agency entrusted with the responsibilities of providing scientific inputs for management, exploration, monitoring, assessment, augmentation and regulation of ground water resources of the country.