It is a well known fact that India, with 4 per cent of the world’s freshwater resources, meets the needs of 18 per cent of the world’s population. Both the government and civil society have failed to address the water crisis. The recent NITI Aayog report states that around 60 crore Indians face very high water stress and every year 2 lakh people die due to scarcity of safe water.

It also mentions two very important facts ~ 1) 70 per cent of our fresh water is contaminated; and 2) groundwater, which accounts for 40 per cent of our water supply, is getting depleted at unsustainable rates. A large number of people in Madhya Pradesh, Chattishgarh, Jharkhand, Odisha, Maharashtra, Karnataka, Telangana and Tamil Nadu are facing an acute scarcity of water. The crisis, post the Green Revolution, is becoming acute in northern India as well. Climate change and population growth are expected to intensify the problem.

An estimated 85 per cent of drinking water needs are dependent on groundwater. At present India withdraws the highest quantity of groundwater in the world, with estimated annual withdrawals exceeding 230 cubic km which is more than the USA’s and China’s put together. However, groundwater supplies in the Indian subcontinent are difficult to quantify because of complex hydrogeological conditions and equally complex tectonic framework, besides variations in climate, rainfall and hydrochemical conditions.

In addition, India’s increasing population and rapid industrial and economic growth have placed enormous demands on groundwater resources. Unfortunately there is lack of reliable data to assess the real condition of various aquifers across different regions of the country and there is no comprehensive action plan at the central or state level for sustainable groundwater management.

The twin satellites of the US and Germany named Gravity Recovery and Climate Experiment or GRACE had launched in 2002 a specially designed mission which could observe changes in water in the continents from space and are revealing hidden secrets of the water cycle. The use of GRACE data in groundwater estimation is showing anew direction to scientists when very little accurate field data are available.

Studies using GRACE data have calibrated global groundwater losses; 13 of the planet’s 37 largest aquifers surveyed between 2003 and 2013 are being depleted as they are receiving little or no recharge. The research team found that the Indus Basin aquifer of north-western India and Pakistan is the second-most overstressed aquifer after the Arabian Aquifer System which is the most overstressed in the world.

The Ganga Brahmaputra basin is also a highly stressed aquifer. These regions rely much more heavily on groundwater during the dry season and drought. Use of GRACE data for small aquifer estimation may not yield the required results, It can be used with Indian remote sensing data like ENVISAT in tandem with more observation data to estimate spatial and temporal variations in groundwater depletion and recharge. This information is extremely critical for regionwise precaution.

Various studies over the past 20 years show that groundwater is being depleted at an alarming rate from the groundwater reserves of Rajasthan, Punjab, and Haryana. More than 109 cubic km of groundwater disappeared between 2002 and 2008. This is double the capacity of India’s largest surface water reservoir, the Upper Wainganga.

A latest study published in 2018 shows that in north-western India the depletion rate is around 40 to 48 mm per year and in the large North Indian Ganga basin it is depleting at an average rate of 20mm per year. Both the regions are major foodgrain producing regions. The scientists also found that northern India’s subsurface water is being pumped primarily to irrigate cropland. This depletion is affecting the densely populated areas of north India and the fertile, irrigated agricultural fields of Punjab, Haryana, Rajasthan and western UP.

The shortage of groundwater has already resulted in ecological damage, depleting water in rivers, deteriorating water quality and subsiding land. Groundwater levels do not respond to changes in weather as rapidly as lakes, streams, and rivers do. So when groundwater is pumped for irrigation or other uses, recharge to the original levels can take months or years.

Last summer, Sonbhadra district on the Sone river basin of eastern UP faced a severe drinking water crisis due to depletion of the groundwater level. This clearly indicates that the groundwater crisis is not restricted to north-western India, it is gradually spreading across the country. A large country with over one billion population, India can no longer accept this level of uncertainty for availability of water.

Indian agriculture is one of the most “water expensive” operations. Around 80 to 85 per cent of our total water consumption is for agriculture. India has all the ingredients that militate against any attempt to tackle the severe groundwater crisis ~ staggering population growth, rapid economic development and water-hungry agricultural fields, which account for about 60 per cent of groundwater use in the country. NITI Aayog is trying to identify and address the crisis at the state level, which may not be a very effective water management strategy. NITI Aayog’s observation indicating that our groundwater use exceeds natural replenishment.

The country requires a sustainable groundwater management policy across the country. Immediate measures need to be taken to ensure sustainable groundwater usage at block or river catchment level; otherwise its consequences will be severe including the collapse of agricultural output and severe shortage of drinking water. Considering the magnitude of the problem and its importance a number of studies, based on modern reliable technology. is necessary on peninsular India and Gangetic North India to assess the availability of total fresh water and its future prospects.

The fresh water availability and the condition of groundwater needs to be estimated at the river catchment level. This will also help finalise the National Water Policy which is pending since 2012. At institutional level River Basin Organisations must be in place with matching autonomy and minimal political interference.

The writer is Executive Director, PAN Network Pvt. Ltd, Kolkata. He may be reached at [email protected]