World Water Day: Groundwater

World Water Day is 22 March 2022. This annual observance was organized by the UN in 1993 to focus attention on the importance of freshwater and to promote sustainable freshwater management. Each year a different theme is chosen, centered on topics relevant to clean water, sanitation and hygiene. The theme for 2022 is Groundwater — making the invisible visible. The UN World Water Development Report (WWDR) is also released each year around World Water Day.

Water is the other finite liquid resource that is increasingly becoming a challenge. Unlike petroleum, however, humans can’t live without water. Today around two-thirds of the global population – four billion people – face water scarcity for at least one month a year. As we head deeper into climate change that number will increase, and the intensity of the problem will increase also. Seasonal water scarcity will become long-term water stress which is the condition of not having sufficient water to meet needs. Increased stress will be concentrated in the arid regions of the Middle East, North Africa, south and central Asia, and the US Southwest. However, no region will be free from water worries; the humid US Midwest may face some level of water stress by 2050. And of course, we’ve already seen that even the temperate rain forests of the Pacific Northwest can succumb to heat and drought — and the associated disaster of uncontrolled fire.

Water availability is affected by physical conditions — such as rainfall, rate of evaporation, and land surface morphology — and human management — such as dams, groundwater extraction, and reservoirs. Climate change will likely affect local precipitation patterns as well as evaporation. Of the two, evaporation may be more critical. We tend to think of the water cycle as rainfall to river to ocean back to clouds, but in reality, evaporation is taking up water at every stage. Evaporation is largely driven by solar radiation and temperature. So climate change has the potential to greatly increase evaporation, leading to decreased flows in streams and rivers, less groundwater recharge, and shrinking reservoirs — perhaps even an inability to store water on the surface at all. 

Changes in Ogallala water levels from before the aquifer was tapped in the early 20th century to 2015. Gray indicates no significant change. Water levels have risen in some areas, especially Nebraska, but are mostly in decline. NCA 2018

Water scarcity will also be affected by human management — of both water and other resources. As demands for energy outpace the availability of fossil fuels, there will be more calls for hydroelectric dams, though it is doubtful that there will be sufficient energy and resources to build these structures. There are already demands for more oil and natural gas production, especially so after Putin’s invasion of the Ukraine and the resulting economic sanctions on this fossil-fuel-rich region. Most conventional wells are now played out, so any increased production will come from hydro-fracking. However, with its intensive water use and then storage of waste in aquifers where toxins are free to migrate into drinking water supplies, fracking for gas or oil is a case of borrowing from one scarce resource to pay for another. Fracking converts potable water into toxic waste, a rather steep price to pay for energy. We can power down our lives. We can’t eliminate our water needs.

Worse yet, many fracked wells are located in the central part of the US, a place that produces a quarter of the nation’s crops, but which is underlain and supported by several ancient aquifers that are running dry. For example, the Ogallala Aquifer is a remnant of Pleistocene glacial meltwater. It receives scant recharge from surface water even when there is substantial rainfall, and agriculture is pumping this body of water much faster than it can be replenished. At current rates of use, it is predicted that the Ogallala will be 70% depleted — that is, water will be unobtainable — within a half century. Thirty percent of wells in Kansas have already run dry. Yet the intensively fracked Permian Basin sits right over this aquifer.

Shallow fracked wells affect groundwater substantially. Water quality is reduced and water levels are depleted in regions of fracking. And there is substantial overlap between the aquifers that are already being dangerously drawn down through other means and the regions with high concentrations of fracked wells. Fracking is creating even more freshwater scarcity in a region wracked by drought and over-use. We are literally poisoning the wells that we haven’t already drained dry.

Another fragility of freshwater supply comes from sea level rise and the increased strength of ocean storms, both brought on by climate change. The most immediate problem of coastal cities and climate change is not flooding as such, though that is the most visible expression of misery. What will soon force migration from these cities is the fact that potable water will be increasingly scarce. Water system infrastructure is built at current sea level, and groundwater, by definition, is below sea level. As seas rise and stronger storm surges throw more ocean water onto land, drinking water will be contaminated with salt and other pollutants, and this will happen long before the streets are flooded. There are springs in Florida — which relies on one of the most threatened aquifers in the world for its drinking water — that have already seen flows decreased by some 60%. As water pressure in this groundwater source is reduced by overuse combined with insufficient recharge, salt water is pulled into the aquifer. The results of this are predictably devastating.

Groundwater salinization is not a problem that can be solved with sea walls and other barriers. Nor is it limited to coastal regions. The Murray River basin in southeast Australia is seeing increasing salinity in surface waters due to a combination of prolonged drought and overuse. But testing of groundwater in this region is showing comparable salt contamination in underlying aquifers as well — because there is no surface water that is not in communication with groundwater (though there is quite a lot of groundwater that does not flow to the surface without human intervention). These are not two distinct systems but one connected flow of water both above and below ground.

So similarly, in regions of intensive industrial agriculture, the nitrates that are pouring into rivers and streams from fertilizer and fecal run-off, are also seeping into our groundwater reservoirs. The Water Boards of California have advised the state to directly address groundwater contamination in the Tulare Lake Basin because of nitrate run-off that flowed into aquifers decades ago. There are communities in this region that can neither afford to treat these contaminated waters nor locate other sources of drinking water. They are relying on wells poisoned by agricultural surface water pollution.

The UN World Water Day website reminds us that nearly all of our liquid freshwater is groundwater. All rivers, streams and lakes combined make up a tiny fraction of a percent of total freshwater. We already rely on groundwater pumping to meet the majority of our freshwater needs. But there is so much water stored in subsurface aquifers that in many drought-stricken regions humans could, with better infrastructure and pollution control, rely on groundwater even in the absence of rainfall. It is estimated that much of the African continent is underlain by enough water to supply most countries through five years of drought, some by over half a century.

Of course, this water is only accessible through drilled wells, most of which require pumping (ie water pressure is not sufficient to force water to the surface in these wells). Furthermore, an increase in pumping over time results in lowering the water level in wells which then translates into a need for deeper wells and more powerful pumps. This cycle results in a continual stream of energy and resource flow necessary to tap into these reserves of water. It is hard to see how these flows will be maintained in a world of increasing scarcity, especially in poor communities. So while the water may be there for the taking, the ‘taking’ may not be there for the water. Still, the resources can be found if there is sufficient wealth in the search. And, in all fairness, those countries which have contributed most to climate instability should be assisting these countries who are most affected by that instability — which, of course, means that wealthy countries should be aiding others in drilling and maintaining these wells. So, with cooperation, increasing reliance on groundwater could be a short-term option to supply water in times of climate-driven drought.

However, nothing is a long term solution. This is a critical fact to remember. As in all finite resources, overuse will exhaust our groundwater supplies (especially when combined with pollution). In many regions this is already a problem, even in places with abundant recharge from rainfall. No place is immune to water scarcity. To underline this, consider that wells are running dry in New England these days. This happens because surface water from rainfall and snowmelt comes in short, intense bursts. Much of the water rapidly drains off the surface and quickly runs down to the ocean. It does not recharge groundwater reservoirs. It doesn’t even do a good job of recharging surface reservoirs in particularly warm summers with high evaporation — or simply high draw-down.

Before water-use restrictions were imposed in 1989, the Quabbin reservoir in central Massachusetts went through a twenty-year period of water use above safe-yield — that is, more water was taken out than could be replenished by precipitation and water flow into the basin. This resulted in dropping water levels in the reservoir and its surrounding region. Because water pressure is always lower on the surface, groundwater will flow to the surface if it can. So drawing down a lake is effectively pumping groundwater. There are wells in this region that are still dry over thirty years later.

Water scarcity will be a fact everywhere, even in a world of increasing warmth and therefore increasing precipitation. In places where the rain falls, it will come in strong storms, much of which will be lost to run-off. Groundwater will not be replenished and wells will run dry. And this as true for wet areas as it is for deserts.

So learn where your water is flowing from and where it is flowing to. How do you affect groundwater viability when you turn on the tap? Ultimately, every drop that flows down the drain is lost to the ocean. So what amount of rainfall recharge is available to groundwater in your region — and is it enough?


©Elizabeth Anker 2022