Global water crisis: what solutions for tomorrow?

1. Address occasional shortages thanks to inter-basin transfers

SHANGHAI, MEXICO, LE CAIRE, LOS ANGELES …

Responding to an uneven distribution of water in space, the canals and inter-basin transfers rely on solidarity between populations to supply many large cities in the event of a shortage. “This water is mobilized geographically from one donor basin to another where human needs are more important”, describes François Molle, geographer at the Research Institute for Development in Montpellier. This is sometimes essential to ensure access to water for all: this is the case, for example, in Outremer, where purification works can be unsanitary or simply absent. The French Biodiversity Office has therefore been funding this type of infrastructure there since 2008.

The method has of course its share of drawbacks. Already, the economic cost of such a structure is often high. In addition, there is a significant environmental cost – hydrology and ecosystems are often modified – which can even be accompanied by a social crisis. As in California, in 1913: the Owens River had been diverted to supply Los Angeles, depriving the ranchers and farmers of the valley of water. “The city was created where there was no water, and it still depends on interbas-sins transfers. It’s a bit absurd but it’s hard to go back”, notes François Molle. Of course, the technique is not a miracle solution. But it is bound to intensify.

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A canal in the Los Angeles area.

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>> Read also: It’s the water rush: how the world is dealing with the water crisis

2. Effectively manage reserves thanks to dams

BEIJING, MANILA, JAKARTA …

The planetary freshwater resource (about 40 million cubic kilometers per year) is much greater than human needs (less than 5,000 km3). The problem is, much of this water doesn’t fall where or when humanity – and primarily agriculture – needs it. How to have water when you want and where you want? One of the solutions put forward is the construction of dams. By capturing water and preserving it in reservoirs, it will then be sufficient to conduct it when it is needed, where it is needed, via canals or aqueducts. A strong argument: they are also a good way to provide carbon-free and controllable energy, with some methane emissions in the tropics. Moreover, it will not be possible to get out of the climate danger zone without building many new structures, according to the International Energy Agency. And to this is added their contribution to the regulation of floods, which are still responsible for thousands of deaths each year in many countries of the South. Finally, if North America and Europe have consumed the majority of good existing dam sites, in Africa and much of Asia barely 10% of these sites have been exploited, and major rivers such as the Mekong or the Congo have configurations favorable to the construction of works.

The dams therefore seem to meet all the criteria!

However, their drawbacks are numerous: in addition to their strong ecological impact and the volumes of concrete they mobilize, studies show that they often generate an increase in social inequalities, via the intensification of agriculture. They also lead to the loss of large quantities of water by evaporation: up to 50% of the stored volume! However, research shows that by covering the canals – which India and California have set out to do with solar panels – these losses can be reduced by 85%.

It's the water rush: how the world is coping with the water crisis

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The Kerr Dam on the Flathead River in Montana (United States).

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3. Take care of groundwater in order to use it sustainably

SAO PAULO, MUMBAI, NEW YORK, ISTANBUL…

The use of groundwater constitutes an effective solution to fight against the water shortage to come in many large cities. The exploitation of these waters also plays an essential, although often unrecognized, role for humanity: their exploitation improves livelihoods, reduces poverty, stimulates the local economy and provides security in times of scarcity.

But it is advisable to mix their use with other techniques. This is what the authors of a study published in August 2021 say in Nature which underline the importance of continuing to reduce the demand for water and to promote its conservation, in parallel with the exploitation of groundwater. These should be used sparingly. Except that their use today is too often unsustainable and uncontrolled.

“No country has been able to anticipate or prevent their overexploitation”, underlines François Molle, geographer at the Research Institute for Development in Montpellier. For example, in India, there are around 20 million wells, but almost 1/6 of the 6,965 groundwater tables are overexploited and the water quality is degraded there, a recent report from the Central Office reads. of the country’s groundwater.

“Many states continue to let it go and even subsidize this race for groundwater, which creates wealth with little public investment”, adds the researcher.

One of the major future challenges is therefore to become aware of the abuses linked to the exploitation of aquifers and to try to shape this technique so that it is as sustainable as possible. Entire communities depend on it.

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Drilling a water well in Kern County, California.

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4. Focus on research to desalinate water efficiently

KARACHI, TIANJIN, LIMA…

The very idea that water is a scarce resource seems absurd when you think that the oceans cover 70% of the globe … Salt water being unfit for consumption, the desalination process – which eliminates the salt to obtain fresh water – has the wind in its sails. As evidenced by the announcement in June 2021 of Jordan which, faced with one of the worst droughts in its history, decided to build a desalination plant on the Red Sea. By 2026, the country hopes to produce between 250 and 300 million cubic meters of drinking water per year. According to an article published in 2019 by a Canadian team from the United Nations University Institute, there are nearly 16,000 operational desalination plants around the world, responsible for around 95 million m3 / day of ‘pure water. But any technique has drawbacks.

Current desalination plants consume a lot of energy and are potentially harmful to ecosystems, with residual salt water being released into the environment. Hence the need for further research.

At the end of 2020, Mihail Barboiu and his team from the European Institute of membranes, in Montpellier, reported having developed a new membrane, combining a polyamide matrix (a polymer) and artificial water channels, allowing three times more desalination. of water than the most efficient commercial membranes on the market, and consume 12% less energy. “We are now developing a pre-industrial prototype intended to produce 100 m3 / day of drinking water, against around 2 m3 / day for the laboratory model, indicates the researcher. If all goes well, our technique could be marketed in two years. “