Our planet needs water solutions

The water paradox

Rise and shine! It’s morning. Normally you would shower, but your local municipality has placed water restrictions due to a severe shortage. There hasn’t been any meaningful rain for over half a year. Forecasters claim that there hasn’t been anything like this in centuries, but this same claim is made almost every year now. Outside, the plants are shades of brown and yellow. Industry has literally dried up. A steady trickle of family and friends leave to seek a living elsewhere. 

Increasingly, this fiction is playing itself out in the real world. In just the past few years, urban centres such as Cape Town and Chennai have just barely avoided zero water. Despite examples of extreme water stress, by mid century, water demand is expected to grow as much as 55% - driven almost entirely by increases in domestic and industrial uses due to population growth and increasing standard of living. 

As current projections stand, over 4 billion people will face some form of water scarcity by 2050 - the majority of which will reside in urban centres. Even if ambitious climate and population growth targets are adopted (under SSP1), only about 20% of water scarcity can be mitigated. 

Our water challenges occur under a seeming contradiction: we are running out of water - yet the world isn’t. In fact, due to the warming planet, increasingly more water is available in the skies. So why is it that water scarcity is such a significant challenge? 

Today’s systems are inadequate

Climate change plays no small role in our water supply cycle and it exacerbates existing water scarcity asymmetries - even though the atmosphere holds more moisture, the moisture content itself is unevenly distributed. Considering we’ve no planet B, nor can we simply move billions of people out of water scarce regions, we need to come up with viable water supply solutions.

Unfortunately, often in the areas where we require it the most, our water systems are woefully inadequate. While traditional reservoir construction and groundwater could in theory relieve water scarcity for 50% and 65% (respectively) of projected water-scarce urban centres, they offer increasingly incomplete solutions and frequently represent more of a liability than an asset. 

Above-ground reservoirs are often the go-to option for municipal water storage, but both the development and maintenance of reservoirs can be prohibitively expensive for developing countries. In addition, they emit large quantities of GHG, disturb natural ecosystems, vulnerable to dangerous natural and artificial failures (e.g. earthquakes and civil conflict), and flood large tracts of land - often displacing communities and cultures in the ensuing inundation. Even with these challenges addressed, due to increasingly irregular precipitation, evaporation, and silting, few reservoirs act as dependable water supply buffers. 

In contrast, the primary challenge with groundwater is that it is often mismanaged. Natural groundwater is often not replenished fast enough to prevent over extraction and is increasingly in short supply - 30% of the world’s groundwater already stressed. In places like California’s central valley and India’s Gangetic plain groundwater is reaching ‘crisis’ levels. In addition, as groundwater levels decrease, it presents an increasing energy problem as well - the resulting energy-CO2 emissions alone contribute around 10% of India’s total GHG emissions.  

Moreover, for the 60% of the world’s inland population living >100km from the world’s largest source of water (untreated seawater), the foremost challenge becomes access to sufficient quantities of water - treated or otherwise. We believe that these challenges can be solved and have highlighted several possible approaches below. 

  • Overhaul the establishment

Starting from established technologies, it may be possible to restore the reliability of groundwater and reservoirs through improved monitoring and integration. Reservoirs are still very useful tools for water distribution - especially for above-ground irrigation - and energy production. Coupling current reservoirs with enhanced groundwater replenishment may improve the upsides of current reservoirs by minimising water loss through evaporation and reducing need for additional water distribution infrastructure. A higher integration between surface water and groundwater could also facilitate directed precipitation capture - making systems more adaptable for an increasingly asymmetric water supply. These integrated systems could be managed in part through improved monitoring of local groundwater levels, quality, and directed inputs and outputs.

  • Integrate new technologies

New technologies could help improve existing above and below-ground reservoirs and adapt them for increasingly irregular water supply. Injection wells coupled with rapid-transfer membranes could facilitate fast groundwater recharge while minimising risk of pollution - such systems could also help manage unexpected rapid increases in water levels such as in high precipitation events or floods. Other approaches such as improved porous foundation work and permeable concrete can help directly return the 90% of urban water runoff not currently captured in developing countries to groundwater. Also, in some areas where brine has infiltrated groundwater, light and low-energy inland-desalination via nano-filtrations, or reverse osmosis could be adopted to make groundwater usable again. 

  • Look to the skies

Finally, a large number of new methods for extracting moisture from the air show a significant amount of promise. These solutions can potentially address even some of the most extreme water scarce areas. Many of the driest places in the world still have significant quantities of moisture in the air - a 10% humidity at 35C has the same water content as a location with 90% humidity at 10C. Even the driest desert in the world, the Atacama, regularly reaches above 40% humidity. Some potential methods to directly extract moisture from air via point source capture can include hygroscopic materials, vapour compression, condensation, and desiccant capture. Alternatively, wide-area precipitation can be induced via artificial cloud seeding, where alternative seeding methods such as cellulosic precipitation induction offer a potentially cost-effective and environmentally friendly alternative to silver iodide. 

The solutions to our water problems are there, we just need to implement them.