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

印度是世界上最大的地下水农业用户。在过去的40年里，从大规模的地表水管理到广泛的地下水抽取，特别是在旁遮普邦、哈里亚纳邦和拉贾斯坦邦的西北部，发生了革命性的转变。因此，印度西北部现在是地下水枯竭的热点地区，“地下水损失率是地球上任何同等大小的地区中最大的”(Tiwari等人，2009年)。这种不可持续的地下水利用变得更加具有挑战性，因为人口迅速增长和工业化对地下水的需求不断增加，再加上气候驱动的水循环变化的潜在影响，但人们对此知之甚少。有一些创新的社会经济战略可以解决这一问题，包括加强补给和地下水储存，但这些战略的实施和成功取决于区域对含水层系统的地质和水文地质以及地下水流动和补给的模式和速度的扎实了解。我们对区域地下水资源的了解主要来自基于卫星数据的低分辨率研究，或来自当地调查；还没有对地下水系统进行大规模的、跨州的综合研究。印度西北部的地下水被认为主要赋存于从喜马拉雅山脉向西南延伸的埋藏的沙质旧河道中，并被细粒泥浆隔开。在地表上只有几个渠道可见；大多数都被掩埋了，必须推断它们的存在。我们的方法基于这样一个前提，即我们必须首先了解含水层系统的地质和几何结构，然后才能估计它对未来一系列复杂压力的反应方式。这意味着我们必须能够描述这些渠道的位置、大小和特征，以及它们的年龄和三维格局。一旦确定了这些特征，我们就可以预测系统未来可能的行为。在这项提案中，我们将首次提供对印度西北部含水层系统的区域评估，以及在水循环和地下水使用方式变化下其演变的模型。我们的项目将结合沉积学、地层学、沉积物路线和盆地演化、水文学和同位素地球化学方面的专业知识，以了解含水层系统的地质框架、其中地下水的年龄，以及地下水位在未来50年可能演变的方式。该提案的成果将包括(1)一个涵盖印度西北部含水层系统的全面数据库，(2)更好地了解地下水的区域来源、年龄和流量，以及(3)一套关于地下水系统将如何对一系列不同的未来情景做出反应的预测。

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.