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FACTS AND FIGURES ABOUT GROUNDWATER Since antiquity, humans have obtained much of their basic water needs from subterranean sources. But for many millennia, their ability to abstract this vital fluid was tiny in comparison to the available water resources. Rapid expansion in groundwater exploitation occurred between 1950 and 1975 in many industrialized nations, and between 1970 and 1990 in most parts of the developing world. Systematic statistics on abstraction and use are not available, but globally groundwater is estimated to provide about 50% of current potable water supplies, 40% by the industrial demand and 20% of water use in irrigated agriculture. Systematic statistics on abstraction and use are not available, but about 50% of current potable water supplies, 40% by the industrial demand and 20% of water use in irrigated agriculture. Today, with a global withdrawal rate of 600–700 km3/year, groundwater is the world’s most extracted raw material. Groundwater systems unquestionably constitute the predominant reservoir and strategic reserve of freshwater storage on planet Earth – probably about 30% of the global total and as much as 98% of all freshwater in liquid form. Calculating of the total volume of global groundwater storage is by no means straightforward, and the precision and usefulness of any calculation will inevitably be open to question. Actual estimates, which are always massive, range from 7 million km3 to 23.4 million km3, but all are subject to major assumptions about the effective depth and porosity of the freshwater zone. Groundwater forms a cornerstone of the Asian ‘green agricultural revolution’, provides about 70% of piped water supply in the European Union, and supports rural livelihoods across extensive areas of sub-Saharan Africa. The case of India is worthy of specific mention, since groundwater directly supplies about 80% of domestic water supply in rural areas, with some 2.8 to 3.0 million hand-pump boreholes having been constructed over the past 30 years. Further, some 244 km3/year is currently estimated to be pumped for irrigation from about 15–17 million motorized dugwells and tubewells, with as much as 70% of national agricultural production being supported by groundwater.
Information from: Source: UNESCO Water Portal, July 2005
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