Groundwater quality and depletion in the Indo-Gangetic Basin mapped from in situ observations
Groundwater quality and depletion in the Indo-Gangetic Basin mapped from in situ observations
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DOI：
10.1038/ngeo2791
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发表时间：
2016-10-01
影响因子：
18.3
通讯作者：
Yadav, S. K.
中科院分区：
文献类型：
--
作者：
MacDonald, A. M.;Bonsor, H. C.;Yadav, S. K.
从跨界印度恒河盆地抽取的地下水占全球地下水抽取量的 25%，维持了巴基斯坦、印度、尼泊尔和孟加拉国的农业生产力。最近对卫星重力数据的解释表明，当前的抽取是不可持续的(1-3)，但这些大规模的解释缺乏有效治理地下水所需的时空分辨率(4,5)。在此，我们报告了来自地下水位、抽取量和地下水质量的高分辨率现场记录的新证据，这些证据表明，可持续地下水供应更多地受到广泛污染的限制，而不是枯竭。我们估计 200 m 深度的地下水量超过印度河、布拉马普特拉河和恒河年流量总和的 20 倍，并显示 2000 年至 2012 年间，70% 的含水层地下水位一直稳定或上升。其余 30% 的地下水位正在下降，相当于年净枯竭 8.0 +/- 3.0 km(3)。在 60% 的含水层内，饮用水地下水的获取因盐度过高或砷含量过高而受到限制。印度北部和巴基斯坦最近的地下水枯竭是在较长的地下水因广泛的运河渗漏而积累的历史中发生的。这种全流域范围内的原位地下水观测综合提供了政策制定所必需的空间细节，以及帮助评估最新卫星重力数据的历史背景。
Groundwater abstraction from the transboundary Indo-Gangetic Basin comprises 25% of global groundwater withdrawals, sustaining agricultural productivity in Pakistan, India, Nepal and Bangladesh. Recent interpretations of satellite gravity data indicate that current abstraction is unsustainable(1-3), yet these large-scale interpretations lack the spatio-temporal resolution required to govern groundwater effectively(4,5). Here we report new evidence from high-resolution in situ records of groundwater levels, abstraction and groundwater quality, which reveal that sustainable groundwater supplies are constrained more by extensive contamination than depletion. We estimate the volume of groundwater to 200 m depth to be >20 times the combined annual flow of the Indus, Brahmaputra and Ganges, and show the water table has been stable or rising across 70% of the aquifer between 2000 and 2012. Groundwater levels are falling in the remaining 30%, amounting to a net annual depletion of 8.0 +/- 3.0 km(3). Within 60% of the aquifer, access to potable groundwater is restricted by excessive salinity or arsenic. Recent groundwater depletion in northern India and Pakistan has occurred within a longer history of groundwater accumulation from extensive canal leakage. This basin-wide synthesis of in situ groundwater observations provides the spatial detail essential for policy development, and the historical context to help evaluate recent satellite gravity data.