Overview of Ground Water in India
The Standing Committee on Water Resources examined the subject "Review of ground water scenario, need for a comprehensive policy and measures to address problems in the country with particular reference to (i) dark blocks, and (ii) contamination of underground water by certain industries" and submitted their report in December 2015.
In this context, we present an analysis of the ground water scenario in the country. This note maps the indicators regarding availability of ground water in the country, the policy framework and some key issues with regard to the sector.
Introduction
Ground water 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. Water moves through these rocks because they have large connected spaces that make them permeable. The area where water fills the aquifer is called the saturated zone. The depth from the surface at which ground water is found is called the water table. The water table can be as shallow as a foot below the ground or it can be a few hundred meters deep. Heavy rains can cause the water table to rise and conversely, continuous extraction of ground water can cause the level to fall.
Figure 1: Graphical representation of ground water and associated terms
Hard-rock aquifers of peninsular India: These aquifers represent around 65% of India's overall aquifer surface area. Most of them are found in central peninsular India, where land is typically underlain by hard-rock formations. These rocks give rise to a complex and extensive low-storage aquifer system, where in the water level tends to drop very rapidly once the water table falls by more than 2-6 meters. Additionally, these aquifers have poor permeability which limits their recharge through rainfall. This implies that water in these aquifers is non- replenishable and will eventually dry out due to continuous usage.
Alluvial aquifers of the Indo-Gangetic plains: These aquifers, found in the Gangetic and Indus plains in Northern India have significant storage spaces, and hence are a valuable source of fresh water supply. However, due to excessive ground water extraction and low recharge rates, these aquifers are at the risk of irreversible overexploitation.
Ground water availability
The overall contribution of rainfall to the country's annual ground water resource is 68% and the share of other resources, such as canal seepage, return flow from irrigation, recharge from tanks, ponds and water conservation structures taken together is 32%. Due to the increasing population in the country, the national per capita annual availability of water has reduced from 1,816 cubic metre in 2001 to 1,544 cubic metre in 2011.2 This is a reduction of 15%.
The figure indicates that ground water is available at a lower level in the northwestern region of the country. There are other significant pockets across the country where the depth of the water level is more than 10 meters. This implies that one has to dig deeper to reach the water table in these regions. When the ground water level crosses 10 metres, sophisticated equipment is required to extract it.
The level of ground water development is very high in the states of Delhi, Haryana, Punjab and Rajasthan, where ground water development is more than 100%. This implies that in these states, 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% and above. In rest of the states, the level of ground water development is below 70%. Over the years, usage of ground water has increased in areas where the resource was readily available. This has resulted in an increase in overall ground water development from 58% in 2004 to 62% in 2011
Ground water extraction and use
Experts believe that India is fast moving towards a crisis of ground water overuse and contamination.
- Ground water overuse or overexploitation is defined as a situation in which, over a period of time, average extraction rate from aquifers is greater than the average recharge rate.
- In India, the availability of surface water is greater than ground water. However, owing to the decentralised availability of groundwater, it is easily accessible and forms the largest share of India's agriculture and drinking water supply.
- 89% of ground water extracted is used in the irrigation sector, making it the highest category user in the country. This is followed by ground water for domestic use which is 9% of the extracted groundwater. Industrial use of ground water is 2%. 50% of urban water requirements and 85% of rural domestic water requirements are also fulfilled by ground water.
Irrigation through ground water
- The largest component of ground water use is the water extracted for irrigation. The main means of irrigation in the country are canals, tanks and wells, including tube-wells. Of all these sources, ground water constitutes the largest share.
- Wells, including dug wells, shallow tube-wells and deep tube wells provide about 61.6% of water for irrigation, followed by canals with 24.5%.
- Figure 5 illustrates the pattern of use of the main sources of irrigation. As can be seen, the share of tubewells has increased exponentially, indicating the increased usage of ground water for irrigation by farmers.
- The dependence of irrigation on ground water increased with the onset of the Green Revolution, which depended on intensive use of inputs such as water and fertilizers to boost farm production.
- Incentives such as credit for irrigation equipment and subsidies for electricity supply have further worsened the situation. Low power tariffs has led to excessive water usage, leading to a sharp fall in water table.
Ground water contamination
- The commonly observed contaminants include arsenic, fluoride, nitrate and iron, which are geogenic in nature.
- Other contaminants include bacteria, phosphates and heavy metals which are a result of human activities including 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.
The Committee on Estimates 2014-15 that reviewed the occurrence of high arsenic content in ground water observed that 68 districts in 10 states are affected by high arsenic contamination in groundwater. These states are Haryana, Punjab, Uttar Pradesh, Bihar, Jharkhand, Chhattisgarh, West Bengal, Assam, Manipur and Karnataka.
Legislative and Policy Framework
- Currently, the Easement Act, 1882 provides every landowner with the right to collect and dispose, within his own limits, all water under the land and on the surface. This makes it difficult to regulate extraction of ground water as it is owned by the person to whom the land belongs. This gives landowners significant power over ground water. Further the law excludes landless ground water users from its purview. Water falls under the State List of the Constitution.
- In order to provide broad guidelines to state governments to frame their own laws relating to sustainable water usage, the central government has published certain framework laws or model Bills. In 2011, the government published a Model Bill for Ground Water Management based on which states could choose to enact their laws. In addition, it outlined a National Water Policy in 2012 articulating key principles relating to demand management, usage efficiencies, infrastructure and pricing aspects of water.
- The Model Bills and National Water Policy address the governance of ground water under the public trust doctrine. The concept of public trust doctrine ensures that resources meant for public use cannot be converted into private ownership. Government being the trustee has the responsibility to protect and preserve this natural resource for and on behalf of the beneficiaries, that is, the people.
- Additionally, they allow every person the fundamental right to be provided water of acceptable quality. It may be noted that the fundamental right to water has been evolved by the Supreme Court and various High Courts of the country as part of "Right to Life" under Article 21 of the Constitution.
- In response to the Model Bill, so far, 11 states and four union territories (UTs) have adopted and implemented ground water legislation. These are: Andhra Pradesh, Assam, Bihar, Goa, Himachal Pradesh, Jammu & Kashmir, Karnataka, Kerala, West Bengal, Telangana, Maharashtra, Lakshadweep, Puducherry, Chandigarh and Dadra & Nagar Haveli.
- Recently Model Building Bye-laws, 2015 bill was passed by the Parliament has included a provision related to rain water harvesting. It mandates rain water harvesting structures in all buildings having a plot size of 100 sq. m or more.
- In order to promote efficient use of water and incentivise its conservation, the National Water Policy outlines the necessity for pricing of water beyond basic needs. It may be noted that the implementation of the part of the policy that aims at providing basic access to water while establishing economic value and full cost recovery is a conflicting intention. In the absence of a suitable financial model, it remains to be seen how water will be allocated to users with limited capacity to pay for the cost. Additionally, it has been noted that the lack of clear guidelines and legally enforceable mechanisms make the policy ambiguous and not effective.
Institutional Framework
- Within the central government, the Ministry of Water Resources, River Development and Ganga Rejuvenation is responsible for the conservation and management of water in the country.
- The Ministry of Rural Development also implements certain programmes related to ground water management. In addition, the Ministry of Environment, Forests and Climate Change is partially responsible for the prevention and control of pollution, including water pollution, and ground water contamination.
- In addition, there are four major central institutions that address issues related to ground water. The main roles of these institutions are summarized in the table below:
