Opinion: Groundwater: out of sight, out of mind?
22 March 2022
On World Water Day Professor Richard Taylor (UCL Geography) and Dr. Mohammad Shamsudduha (UCL IRDR) explore equitable and sustainable use of groundwater.
Today is World Water Day. Despite the centrality of water in our everyday lives and life itself, we often mark this day not by reminding ourselves of all that water brings but of the consequences of its absence or contamination. Today, hundreds of millions of people around the world still do not have access to basic water services and, in England, every river is too polluted to support its ecology or officially fit for swimming. As the American polymath Benjamin Franklin noted, “when the well runs dry, we (shall) know the worth of water.” This direct reference to groundwater, the water flowing through the pores and cracks in rocks beneath our feet, is fitting as the theme of World Water Day 2022 is Groundwater: Making the Invisible, Visible.
Groundwater differs from the water running off into rivers, lakes and wetlands as this underground flow derives from the infiltration of precipitation that has occurred over periods ranging from years to decades and, in places, millennia. Much of the estimated ~23 million km3 of groundwater in the upper 2 km of the Earth’s crust is ancient, yet the shallower component of groundwater replenished over the last half-century still greatly exceeds all other unfrozen freshwater on Earth.
As the world’s largest distributed store of freshwater, groundwater plays a vital role in not only sustaining aquatic ecosystems during periods of low or absent rainfall but also providing access to safe water, especially to off-grid communities. In drylands stretching across ~40% of world’s land area, groundwater is often the only perennial source of freshwater. It is estimated that half of the world’s drinking water supplies and a quarter of all the water used in irrigation are currently sourced by groundwater drawn from wells and springs. Here in the UK, half or more of the water supplied to the Midlands and southeastern England derives from groundwater.
Due to its origin, groundwater flowing through permeable geological formations known as aquifers is generally more resilient to climate variability and change than surface waters. Consequently, adaptations to drought, whose frequency and severity are amplified by global warming, often increase dependence upon groundwater as recently witnessed in Cape Town’s avoidance of Day Zero. It has even been argued that human evolution itself relied on the continuity of spring discharges during periods of extreme drought.
Groundwater depletion through intensive pumping for irrigation from large aquifer systems around the world (World Water Development Report 2022).
Notwithstanding groundwater’s invaluable attributes, it is not immune to overexploitation and contamination. Groundwater depletion in some of the world’s most productive food-growing regions such as the California Central valley, North China Plains, northwest India, and the Southern High Plains of the US threatens global food security. Similarly, groundwater depletion beneath some of the world’s most rapidly growing cities such as Dhaka (Bangladesh) and Nairobi (Kenya) constrains reliable provision of safe water. Groundwater depletion in both contexts disproportionately affects lower-income households and smallholder farmers who are typically less able to engage in a “race to the bottom” and by drilling deeper wells.
The salinisation of coastal groundwater induced by both intensive pumping and global sea-level rise constrains groundwater use in low-lying nations across the world and has the potential to force millions of people to leave their homes. Use of groundwater is also impaired by the natural leaching of solutes from its host rocks. Globally, the most problematic natural pollutants posing the greatest threats to public health and affecting many millions of people are fluoride and arsenic; the latter in Bangladesh is responsible for what has been described as “the largest mass poisoning in history.” Human activity, be it indiscriminate use of pesticides and fertilisers in agriculture, inadequate sanitation infrastructure, or ineffective regulation of industrial practices, also threatens the sustainability of groundwater use.
As groundwater is out of sight, it has long been out of mind. Investment in monitoring and evaluation in many countries remains very limited and is a tiny fraction of that allocated to surface water resources. There has also been a lack of investment in training and education in groundwater science, known as hydrogeology. The removal of scholarships for MSc study in the UK, for example, led to the closure of post-graduate programmes in hydrogeology including at UCL during the 2000s. Ironically, this decline occurred just as climate change began to amplify the vital importance of groundwater resources, globally and locally. The reversal of the decision by the University of Birmingham in 2016 to “to disinvest in hydrogeology” and close its MSc programme - after much protest - marked an important event bucking this trend.
Like fisheries, groundwater is a common-pool resource in which The Tragedy of the Commons – a situation where individual users act in their own self-interest to deplete or degrade a resource, contrary to the collective good - remains an ever-present threat. The Nobel-Prize winning economist Elinor Ostrom showed, however, that cooperation is possible. She identified conditions from case studies that favoured shared use of groundwater in which a community of users regulates individual access to develop common-pool resources prudently and sustainably.
Small-scale irrigation of an onion crop by groundwater from an alluvial aquifer along the River Goulbi de Maradi in southeastern Niger (photo: Boukari Issoufou).
At UCL, we are working with allied research institutions and stakeholder communities in tropical Africa and South Asia to explore pathways by which groundwater can be used not only to adapt to the amplification of floods and droughts brought about by climate change but also to help to realise by 2030 UN Sustainable Development Goals (SDGs) 6 (water for all), 2 (end hunger), and 13 (combat climate change impacts) among many others. With support from UCL’s UN SDGs: Pathways to Achievement scheme 2021-22, our international transdisciplinary team is meeting in the coming months with decision makers in Niger and Tanzania to promote equitable and sustainable use of groundwater in drylands that is informed by recent research. Our collective aim is to make groundwater visible through the improved livelihoods and wellbeing of communities with climate-resilient access to safe water.