The structure and dynamics of groundwater systems in northwestern India under past, present and future climates

India is the largest agricultural user of groundwater in the world. The last 40 years has seen a revolutionary shift from large-scale surface water management to widespread groundwater abstraction, particularly in the northwestern states of Punjab, Haryana and Rajasthan. As a result of this, northwestern India is now a hotspot of groundwater depletion, with 'the largest rate of groundwater loss in any comparable-sized region on Earth' (Tiwari et al., 2009). This unsustainable use of groundwater becomes even more challenging when set increasing demands from a burgeoning population and industrialisation, together with potential but poorly understood effects of climate-driven changes in the water cycle. There are a number of innovative socio-economic strategies that can address this issue, including enhanced recharge and subsurface water storage, but their implementation and success depend on solid regional understanding of the geology and hydrogeology of the aquifer systems, and of the patterns and rates of groundwater flow and recharge. What we know about regional groundwater resources comes largely from either low-resolution studies based on satellite data, or from local investigations; there has been no large-scale, cross-state integrated study of the groundwater system. Groundwater in northwestern India is thought to be largely hosted within buried, sandy former river channels, which extend from the Himalayas toward the southwest and are separated by fine-grained muds. Only a few channels are visible at the surface; most are buried and their existence must be inferred. Our approach is founded on the premise that we must first understand the geology and geometry of the aquifer system before we can hope to estimate the way it will respond to a complex set of future stresses. This means that we must be able to describe the locations, sizes, and characteristics of these channels as well as their age and three-dimensional pattern. Once these characteristics are determined, we can forecast the likely future behaviour of the system. In this proposal, we will provide, for the first time, a regional assessment of the aquifer system in northwestern India, along with models for its evolution under changes in the water cycle and in the way in which groundwater is used. Our project will combine expertise in sedimentology, stratigraphy, sediment routing and basin evolution, hydrology, and isotope geochemistry to understand the geological framework of the aquifer system, the ages of the groundwaters within it, and the ways in which groundwater levels are likely to evolve over the next 50 years. The outcomes of the proposal will include (1) a comprehensive data base that covers the northwestern Indian aquifer system, (2) much better understanding of regional sources, ages, and flow rates of groundwater, and (3) a suite of predictions for how the groundwater system will respond to a range of different future scenarios.

Our proposed project will have four main outcomes: (1) a geological understanding of the geometry and spatial distribution of the shallow aquifer system in the western Indo-Gangetic Plains, (2) a predictive model for the 3-D arrangement of fluvial channel sands that can be applied to understanding aquifer distribution in the deeper subsurface, (3) establishment of the age, sources, and dynamics of groundwater in this aquifer system, and (4) an understanding of potential hydrological evolution of the aquifer system in response to varied stresses, including changes in future patterns of precipitation and abstraction or recharge. More broadly the project will provide an example of an integrated aquifer impact study based on sound geological knowledge, isotope-based reconstruction of groundwater dynamics and numerical-modelling assessments of aquifer distribution and hydrological evolution. This has potential application in other parts of the Indo-Gangetic basin, and more broadly to other aquifer systems composed of fluvial palaeochannels.

The outcomes of our research will have impact at local and national levels in India, but also internationally through application to similar hydrogeological systems. At the same time, we must be realistic; the three states in the study area contain over 100 million people and groundwater use in the region has become highly 'atomised', with large-scale water management largely supplanted by individual water users armed with pumps (Shah 2009). The potential for local impact is extremely limited. Thus, we argue that the impact of the research is best aimed at state and national levels. A primary target of our study will be to have direct impact on the development of water management plans in the affected states via contact with officials in the relevant state water resources agencies (Haryana, Punjab and Rajasthan). Our study is also relevant for policy-making institutions at the national level. These include the Central Groundwater Board (CGWB), with which we have existing contacts through co-Is Kumar and Shekhar, as well as a set of research institutes.

We will organize a workshop in March each year during the UK field visits to India and will invite a range of stakeholders, including representatives from the Central Groundwater Board (CGWB), state government groundwater department (as water is a state subject), IRI, ICRISAT, CSSRI, several NGOs, and municipal governments in the areas where our field work is based. The goal of these workshops will be to establish a two-way dialogue - both to apprise the stakeholders of our ongoing work and outcomes, but also to hear concerns and viewpoints on the relative priority and importance of the work described here, and to get outside perspectives on the leading issues and uncertainties. We will also establish a dynamic GIS database containing existing geological and groundwater information from the study region and will populate this with our own new data collected during the course of the project. This GIS database will be made available to stakeholders and will be provided to the Central Groundwater Board to help in formulating water management policies. We plan to set up groundwater monitoring stations at several sites as a part of our research. In the final year, we will dedicate 1-2 months of project time to evaluate the project findings to translate key project science into non-technical language that can be put forward for broader delivery, and develop specific recommendations. We will deliver a final report that summarises the key scientific findings, presents the primary data and numerical modelling simulations, and presents recommendations and suggested 'best practise'. A non-technical summary of this report will also be generated. This report together with the GIS database will be archived at NERC Designated Data Centres and MOES Designated Centres.