Hydrogeology in Strategic Water Conservation

Hydrogeology in Strategic Water Conservation

By: Himanshu Kulkarni, The author is Executive Director, Advanced Center for Water Resources Development and Managemenet, Pune.
Conventional approaches to conservation of groundwater have not considered the need to involve an understanding of aquifer measurement and hydrogeology. Considering India’s diverse geography, it is pertinent to develop a scientific understanding of underlying geology of groundwater resources and how aquifers work.
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Groundwater resources are the lifeline of India’s water supply, in rural-agrarian situations and in the growing urban-industrial context. Nearly 90 per cent of rural domestic water use is based on groundwater, 70 per cent of water used in agriculture is pumped from aquifers and increasing evidence points to the fact that 50 per cent of urban water usage is groundwater (Ministry of Drinking Water, River Development and Ganga Rejuvenation, 2017).

Put together, these statistics indicate that at least 100 million Indians use groundwater in India daily, one way or the other. On one hand this dependency underscores the importance of groundwater but on the other it also demands a careful articulation of groundwater management strategies.

India has emerged as the largest user of groundwater in the world since the 1980s (Shah, 2009; Margat and Van der Gun, 2013), with trends clearly showing a growing dependency on one hand and a deepening and widening crisis on the other. Groundwater over-abstraction and contamination together have led to a high level of vulnerability of resources and population across large swaths of India’s landscape, with nearly 60 per cent (Kulkarni et al, 2009) of the districts being affected by depleting or contaminated groundwater or both.

Further, stressed groundwater resources are not just about depleting and contaminated groundwater, but also about a common pool resource coming under competition, leading to conflict between different users. Intra-sectoral competition is observed in agriculture, domestic, industrial and ecosystem users, clearly representing the deepening of the groundwater crisis. What is even more serious is the intersectoral competition, suggesting that the groundwater crisis is also widening and is therefore, now at scale. Groundwater competition has many dimensions but is usually a result of a race between the supply and demand wherein the stocks of groundwater (availability and quality) are often presumed to be infinite.

Recent regional scale assessments reveal that while the northern and eastern parts of India are still undergoing acute usable groundwater depletion and stress, encouraging developments in replenishing groundwater scenarios are detected in the western and southern India under proper water resource management practices (Bhanja et al, 2017).

Groundwater Management: Building Science into Conservation

The high degree of groundwater vulnerability in India calls for groundwater management strategies that include supply and demand side interventions. At the same time, in order to match supply and demand, resource understanding becomes imperative. Hence, acknowledging, recognising and understanding aquifers must all become part of the groundwater management strategy, even at a microwatershed scale (Kulkarni et al, 2004 ). Conservation practices, particularly groundwater recharge, becomes an important component of such a strategy.

Need for better methods of aquifer measurement: Watershed projects remain one of the most popular and successful models of decentralised and hydrology-based conservation practices in India. Conventional watershed projects that use the concept of ridge-to-valley, at the scales of micro-watersheds (100 to 1000 ha) implythat groundwater recharge strategies are decided on the basis of slopes, soils and land-use without due consideration to hydrogeological factors like the underlying geology, aquifers, their properties and most significantly their recharge areas. Even basic hydrogeology that includes the exposures reflecting the tops of aquifers can make a difference to optimising sites for locating recharge structures such as percolation tanks. One such application of hydrogeology is explained in Figure 1.

Figure 1 (a) shows how after the first conventional criterion of slopes is applied, watershed practitioners came up with four plausible sites for groundwater recharge. Subsequently, in Figure 1 (b), using the  hydrogeological mapping methodology, combined with slopes, the same set of practitioners selected two of the four locations for constructing percolation tanks, leading to objective-oriented conservation and optimisation of structures including more efficient investments. A case in point is the watershed programme adopted by organisations like Samaj Pragati Sahayog and WASSAN, non-profits working in Madhya Pradesh and Telangana respectively. These organisations have imbibed hydrogeology based watershed management planning in their current approaches to achieve such efficiencies.

Customising conservation efforts for specific situations: Himalayan springs : India’s geodiversity requires a shift away from standardised, straight-jacketed conservation efforts that consider only slopes, land use, soils and run  off as the main parameters. The mountain regions of India including the Himalayan and sub-Himalayan states, the Eastern and Western Ghats and other hilly provinces such as the Aravalli are cases in point. Conventional thinking on groundwater presumes that mountain regions have steep slopes and hence, preclude groundwater occurrence. Such presumptions have translated into even lesser attention to groundwater in the mountainous areas of India, including the Himalayan region. At least two-thirds of the population living in the Himalaya depends entirely on spring water for their daily needs. There are increasing reports from many of India’s mountain regions that springs are drying. Climate change, especially erratic precipitation, is affecting spring discharges along with changes in landuse and landcover.

Springs in the Himalaya are an important cultural symbol, while also performing the crucial role of providing base flows (groundwater discharge to river channels) to Himalayan streams and rivers. Base flows consequently help maintain the ecological balance of a region by ensuring sustained river flows. In fact, the sources of many rivers in India are in the form of springs, around which religious places have evolved. This is clearly symbolic of the fact that there is groundwater at the head reaches of many such mountain regions that have a long-standing heritage. It is only quite recently that the Central Ground Water Board (CGWB) recommended a provision for assessing spring resources in its periodic groundwater assessment, admitting that the GEC 1997 Methodology, while excluding hilly areas that have slopes more than 20 per cent, might have ignored springs in their previous assessments (CGWB, 2017 ).

Need for better understanding of Himalayan springs: Springs are point sources of groundwater discharge and although spring water emerges and flows on to the surface of the earth, springs are often fed by aquifers, a system of rocks capable of storing and transmitting sufficient quantities of water. Different types of springs are constituted out of various permutations and combinations of the slope and underlying geology—i.e. a combination of the watershed (hydrological unit) and underlying aquifer systems (hydrogeological units). Such a combination, along with information on the nature of vegetation and landuse, provides conservationists the fundamental planning base for undertaking augmentation and protection measures for spring water. Recharge measures for improving spring discharge and quality are now being implemented in many locations across the Himalayan region (Mahamuni and Kulkarni, 2012 ).

Having established springs as groundwater, it is also important to note that groundwater is a common pool resource and the effects of augmentation by a few are enjoyed by many, while on the other hand, the effects of over extraction of the same aquifer by a few—through wells, can harm a larger population dependent on them. Moreover, unlike wells, springs cannot be pumped to extract water. While wells are human-made sources of accessing aquifers, springs are natural discharge points of the aquifer that provide access of water to people. Springs provide water at the specific discharge rates that are an effect of the characteristics of the aquifer providing discharge to the spring.

Need for better legislation for large scale drilling in mountains to extract groundwater : Drilling, in the same manner as has been followed in the rest of India, has begun in large parts of mountainous regions backed by the need to improve agricultural productivity, access to drinking water and to enable industrial growth, thereby affecting ecological equilibrium. Although the sources for access—springs and wells, are different, the resource from which both abstract remains the same—aquifers. Large scale drilling in the mountains in the absence of regulation and management principles would lead to a competition between uses and users of groundwater. The conflict between the two types of sources tapping the same aquifer will in addition affect the sustainability of river flow. Moreover, this will lead to iniquitous access, distribution and availability of drinking water in such regions, prompting a more comprehensive approach of resource management that is integrative of conservation measures. It would thus necessitate recharge and participatory water management across springsheds.

Hydrogeology: Conservation as a Function of Science, Communities and Regulation

Protecting groundwater resources from impacts of exploitation and contamination requires three basic components within a conservation approach.

  • An accurate understanding of groundwater in an area, the scale of such understanding depending upon which of the different hydrogeological settings such an area falls under.  This would lead to aquifer level information and management.
  • Participatory approaches (including social norms) to groundwater management including the match between hydrogeologic, hydrologic, administrative / community boundaries.
  • Robust legislation that moves beyond the command and control and is aligned with participatory mechanisms of groundwater management. Such legislation would protect collective action around groundwater, with the objective of not just ensuring sustainability of the resource but equitability as well.

Bringing about a participatory, community-based process of groundwater management is challenging, but in a system of highly decentralised groundwater use, centralised systems of command-and-control are unlikely to work. The contours of a participatory programme will require a different line of thinking to current approaches and should involve detailed understanding of the aquifer or groundwater system, developing community-based protocols of groundwater recharge, use and equitable distribution and enabling an overarching legislation that not only ensures water security but also enables an environment wherein equitability of access and sustainability of the environmental needs
is ensured.

References

Bhanja, S. N., Mukherjee, A., Rodell, M., Wada, Y., Chattopadhyay, S., Velicogna, I., Pangaluru, K. and Famiglietti, J. S. (2017). Groundwater rejuvenation in parts of India influenced by water-policy change implementation. Scientific Reports, Volume 7, Article number 7453 (2017).

Kulkarni, H., Vijay Shankar, P. S. and Krishnan, S. 2009. Synopsis of groundwater resources in India: status, challenges and a new framework for responses. Report submitted to the Planning Commission, Government of India. ACWA Report ACWA/PC/Rep – 1.

Kulkarni, H., Vijay Shankar, P.S., Deolankar, S.B. and Shah M. 2004. Groundwater demand management at local scale in rural areas of India: a strategy to ensure water well sustainability based on aquifer diffusivity and community participation. Hydrogeology Journal (Springer), v. 12(2), 184–196.

Mahamuni, K. and Kulkarni, H. 2012. Groundwater resources and spring hydrogeology in South Sikkim, with special reference to climate change. Climate Change in Sikkim: Patterns, Impacts and Initiatives. M. L. Arrawatia and Sandeep Tambe (eds). Information and Public Relations Department, Government of Sikkim, Gangtok. 2012, Chapter 16: 261-274.

Margat, J. and van der Gun, J. 2013. Groundwater around the world: a geographic synopsis, CRC Press / Balkema, Taylor & Francis. 348 p.

Ministry of Water Resources, River Development and Ganga Rejuvenation. (2017). Groundwater Estimation Committee – GEC – 2015. Ministry of Water Resources, River Development and Ganga Rejuvenation, 280p.

Shah, T. 2009. Taming the Anarchy: Groundwater Governance in South Asia. Resources for the Future, Washington DC and International Water Management Institute, Colombo, 310p.

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