Aquifer mapping programme critical to raise groundwater levels

India's agricultural production journey — from external dependency to meet foodgrain requirements at the time of Independence to self-sufficiency today — is intricately tied to the groundwater resources of the country.

Today, no country in the world is as dependent on groundwater to sustain its water needs as India. The country consumes about a quarter of global groundwater, which is more than the next two countries combined, USA and China.

Though huge investments have been made over the decades for surface water-based schemes for irrigation and drinking supply, groundwater remains the lifeline of water security. But reckless exploitation of aquifers is gravitating India towards a water disaster.

Assessment by the Central Ground Water Board (CGWB) and research based on GRACE satellite data amply demonstrated rapid aquifer desaturation at many places.

Of the 6,881 blocks/talukas assessed in the country, 17 per cent are overexploited. These overexploited areas have invaded all aquifer typologies — from prolific soft rocks aquifer system in Punjab, Haryana and western Uttar Pradesh, complex heterogeneous aquifer systems in arid areas of Rajasthan and Gujarat to low-potential hard rock aquifers in Karnataka, Tamil Nadu, Telangana and Maharashtra.

The economic and social consequences of groundwater overexploitation has led to mounting economic burden on farmers owing to relentless construction of deeper new wells, increased energy cost to lift water, enhanced water salinity and spread of geogenic contaminants — arsenic, fluoride, salinity — and ingress of seawater in freshwater aquifers in coastal areas.

Further, we are yet to fully comprehend its impact on environment and ecology. The likely effects are diminishing flow of non-glacier fed rivers, drying up of wetlands, changes in hydraulic behaviour of aquifers—particularly in the multi-aquifer setup in the Indo-Ganga-Brahmaputra Plains.

THAT’S WHY GROUNDWATER resource mapping needs urgent attention. Groundwater resource mapping (often referred to as aquifer mapping) provides a holistic understanding of aquifers and ways of its sustainable use.

Since the formation of CGWB in 1972, the primary objective of surveys was to delineate potential areas for groundwater exploitation and recommending maximum possible extraction to the user departments.

As many places today are rampant with overexploitation, sustainable framing measures and their adaptation warrant a wide under-standing of aquifers — their geometry and hydraulic properties, resource availability, hydrochemical processes and contamination susceptibility, capability to artificial recharge, inter-aquifer behaviour in case of a multi-aquifer system, response to extraction and recharge and much more.

On the basis of the recommendations of the 12th Plan Working Group on Sustainable Groundwater Management of the erstwhile Planning Commission (now NITI Aayog), the ambitious National Aquifer Mapping and Management Programme (NAQUIM) was launched in 2012, with CGWB as the executing body.

The programme aims to cover more than 25 million km2 that have been delineated as “hydrogeologically mappable”. 

Structurally there are four stages of activities in NAQUIM:

• Collection, compilation and analysis of existing data. Based on the data requirement protocol, data gaps are identified;
• The required data is then generated in data gap areas/domains through an array of scientific investigations;
• Integration of data, developing lithologic models and configuring aquifers. The hydraulic properties, resource behaviour, water level regime and chemical quality is established in space-time domain; and,
• Various supply and demand side interventions are worked out and recommended to sustainably use groundwater. Here, local issues are also addressed.

Various government research institutions such as the Indian Institute of Sciences, Bengaluru, IIT Kanpur, the Geological Survey of India, Kolkata, the National Remote Sensing Agency, Hyderabad and the National Geophysical Research Institute, Hyderabad are roped in at various levels.

The outputs are validated, discussed and checked at different stages. Finally, they are cleared by a committee of independent interdisciplinary experts. The reports are then presented to the State Level Coordination Committees, formed in each state and Union Territories.

The immense benefits of NAQUIM can be harvested by numerous stakeholders. Since groundwater is a key component in a number of programmes launched by various Union government ministries, a carefully-crafted convergence of NAQUIM outputs can help in optimising the benefits.

For instance, in arsenic-contaminated Indo-Ganga Brahmaputra Plains, alternative arsenic-free aquifers are delineated and suitably designed wells are being constructed for community drinking water supply, using NAQUIM outputs. Similarly, various state government schemes on water conservation can also considerably improve their benefits and outcomes.

One of the major objectives of NAQUIM is to promote participatory groundwater management. This can be achieved by empowering communities with a seamless flow of information and understanding of local aquifers.

CGWB and various departments of the Jal Shakti ministry are making efforts in this regard. All NAQUIM reports can be accessed online and awareness camps are being organised to disseminate the outputs.

For faster outputs and wider reach, an exhaustive, user-friendly and easily retrievable web-based system is urgently needed where all information, both graphical and numerical, can be uploaded on a GIS platform.

It is also imperative to undertake case studies in different aquifer types to demonstrate the efficacy of the adopted measures recommended by NAQUIM for sustainable management of groundwater and sharing it within communities through properly designed wells, irrigation practices and adopting artificial recharge through a consultative process. The present scale of mapping is 1:50,000, which should be fine-tuned to 1:25,000 scale in critical and contaminated areas.

Though a couple of mobile apps have been developed to disseminate information, they lack robustness and are hardly used. These need to be popularised. The progress of NAQUIM needs to be speeded up on a mission mode. A strong political and administrative will is needed to converge the outputs with the programmes.

Unfortunately, groundwater departments in most states are in a sorry state. Except for couple of states, they are either rickety, neglected or even non-existent. These departments should be strengthened with domain specialists to support NAQUIM. Because unlike geological mapping, NAQUIM is a continuous process that requires regular updating of data as it deals with a dynamic groundwater system.

(The author is Secretary, International Association of Hydrogeologists, India Chapter, and Former Member, CGWB)

(This article was first published in Down To Earth's print edition dated September 16-30, 2019)