Since earliest times humankind has met much of its needs for good quality water from subterranean sources. During the 20th century there was an enormous boom in waterwell construction for urban water-supply, agricultural irrigation and industrial processing – facilitated by advances in well drilling, pump technology and geological knowledge – and groundwater became a key resource supporting human well-being and economic development.
Comprehensive statistics on groundwater abstraction are not available, but global withdrawals are estimated to have passed 900 km3/a in 2010, providing some 36% of potable water-supply, 42% of water for irrigated agriculture and 24% of direct industrial water-supply1, with proportions varying widely from country to country and across larger countries. Moreover, groundwater is also often the only option for meeting rural water-supply needs. The social value of groundwater should not be gauged solely by volumetric use, since it brings major economic benefits per unit volume, because of local availability, scaling to demand, high drought reliability and generally good quality (requiring minimal treatment). The dependence of many cities and innumerable medium-sized towns on groundwater is increasing, and the contribution of groundwater to irrigated agriculture in terms of crop yield and economic productivity is high.
Why is it essential for groundwater considerations to be included explicitly in the Indicators for UN SDG-6 : Water?
Worldwide the generally excellent natural quality of groundwater makes it the preferred source of drinking-water. Aquifers have widespread geographical occurrence and naturally provide the functions of water-supply filtration, storage, distribution and protection.
Moreover, groundwater storage represents a natural buffer against unpredictable water demands arising from accelerated global warming. It is thus essential that groundwater be factored-in fully to the procedures being drawn-up to evaluate the progress in achieving UN SDG-6 Targets.
Groundwater factors will exert a major influence on two distinct facets of SDG-6 – the ‘engineering of human water services’ (Target 6.1) and the ‘status of the water resource base’ (Targets 6.3, 6.4 & 6.6) – there being a strong link between provision of the former and sustainability of the latter. In this regard groundwater governance will widely need to be strengthened, so as to prevent further resource depletion and quality degradation.