The Case of ‘ZERO’ Level of Groundwater

Nitin Bassi

Of late, newspapers in India are packed with the articles reporting the findings of the Niti Aayog’s (India’s policy think tank) report ‘Composite Water Management Index 2018’ (latest one released in 2019) which presented a very grim picture of the water situation in the Indian cities. The report has even gone to the extent of declaring that the groundwater level in 21 major cities in India, including Delhi, Bangalore, and Hyderabad, are expected to reach ‘Zero’ by 2020. For the people who understand and believe in the hydrological (water) cycle this came as a surprise. They always thought that rains bring water which flows to surface water bodies and to aquifers (underground rock formation bearing water) and this process is repeated every year. Then where does this ‘Zero level’ come from? In this article, the reality behind this doom’s day prediction is provided.

First of all, one needs to understand the methods used to assess groundwater resource availability and estimate the stage of groundwater development by the Central Ground Water Board (CGWB) in India. The groundwater assessment exercise quantifies resource availability based on the annual replenishable (dynamic) groundwater resources. This is the water that occurs as a recharge to aquifers every year. In the case of India, the main sources of groundwater recharge are rainfall and the snowmelt. Nevertheless, seepage from canals and return flow from the irrigated cropland also contribute significantly to annual recharge. The stage of groundwater development which represents the total withdrawals (for irrigation, municipal and industrial uses) in relation to availability considers only the dynamic groundwater resources (which is available every year) in the ‘denominator’. The static groundwater resources which are accumulated over several years or decades are not considered. But that quantum is significant in many regions, especially where deep alluvial strata are present (Cambay basin, Gangetic plans, and the Indus basin areas).

Therefore, the stage of groundwater development in the assessment units in some such areas is over 100%, and such units are referred to as ‘over-exploited’. But this does not mean that the aquifers in such units have no water, instead, it only means that the static groundwater resources there are being tapped. Even the most recent assessment report (2017) of the CGWB states that ‘1034 units in various states have been categorized as ‘over-exploited’, i.e., the annual groundwater extraction exceeds the net annual groundwater availability and significant decline in long term groundwater level trend has been observed either in pre-monsoon or post-monsoon or both’. It is important to note that there is no mention of any water stress or ‘zero groundwater level’ in the report.

Secondly, one needs to be careful in interpreting the data presented in Niti Aayog’s CWMI 2018 report in support of the ‘zero groundwater level’ theory. CWMI is based on nine themes related to water, which comprise 28 indicators in total. These ‘themes’ mostly cover areas related to various schemes of the central and state government on water resources development and management and rank the Indian states according to their performance in implementing these schemes. The specific areas include groundwater and surface water rejuvenation programmes, execution of major and medium irrigation schemes, watershed development, participatory irrigation management, on-farm water use, rural and urban water supply, and policy & governance. On the groundwater front, assessments undertaken by the CGWB and/or state groundwater department are referred to. Hence, none of the components of the CWMI is based on any thorough scientific assessment of the actual resource condition and the need for resource development and management interventions in a state.

To our surprise, the narrative of ‘zero groundwater level’ is based on an article from the World Bank published in some leading newspapers of India, and this has been clearly referred to in the CWMI 2018 report. However, everyone has been made to believe in this ‘Zero level’ without doing any proper verification of the authenticity of the original source. At least Niti Aayog should have made it clear that this is not based on their own analysis. Instead, the newspaper articles were used to highlight the ‘grim water situation’ in the Indian cities which is now even used as fact during the hearing in the Supreme Court and in the National Green Tribunal. This is no different from the IPCC findings on the ‘Great Himalayan Glacier Retreat’ which were based on a media interview.

There is no denying of the fact that groundwater abstraction in the assessment units that are categorised as ‘overexploited’, and having alluvial aquifers is unsustainable. Such abstractions are mainly for irrigation and is mainly occurring in western Rajasthan, north Gujarat, Punjab, Haryana and a few pockets in western UP. On the other hand, in the areas underlain by hard rocks, there is very little groundwater stock, and these areas experience seasonal groundwater scarcity as the annual recharge of the shallow aquifers from rainfall and other sources get depleted very fast. Such areas include large parts of Madhya Pradesh, Maharashtra, Andhra Pradesh, Karnataka, and Tamil Nadu. Abstraction of the static groundwater from the un-weathered strata is prohibitively expensive. Hence, there is no chance of permanent depletion of groundwater in such areas. Unfortunately, such nuances are not captured while estimating the stage of groundwater development in such areas.

Instead of doom’s day predictions, the time has come for taking some pragmatic and tough decisions to improve water resources management in the country.

Nitin Bassi is a Principal Researcher with the Institute for Resource Analysis and Policy (IRAP) and based at their Liaison Office in New Delhi. Email: [email protected]