Global warming is affecting the availability of water, and the measures taken to stem this decline in the resource must include many technological components. About ten of the 360 ??members of the Academy of Technologies looked into it, in order to inform public policies.
And their conclusion is clear: there is an urgent need to act, collectively, to maintain access to water that meets the needs of society. “All the forecasts show that the situation is becoming worrying,” says academician Yves Lévi, pharmacist by training, professor emeritus at Paris-Saclay and water specialist.
For Yves Lévi, several technological solutions, of a different nature, could help meet water needs in the decades to come. Firstly, wastewater and rainwater could be reused, “subject to sanitary controls”, especially since most of the necessary facilities already exist.
The report also mentions the possibility of desalinating seawater, even if, for Yves Lévi, “in France, it is not the most suitable technology”. However, the water specialist considers that this process, which is very expensive and energy-intensive today, could see its cost drop in the next ten to fifteen years, with a sharp increase in the coastal population, and that it could then become an effective solution.
“While we must store water in the best conditions, the discussions on this subject have taken a more political than technical turn”, regrets the scientist, who warns: “Technologies are components of the global strategy, they are contributions for the resolution of problems, they will not solve them alone. There are indeed other ways to optimize the use of water, in particular through the reduction of consumption.
The decline affects society as a whole, and requires inventing “collective sobriety practices” to control demand, as the members of the Academy write in their report.
These practices concern both agriculture, with more appropriate irrigation, or even a change of period and type of crop, as well as industry or leisure. “You have to make everyone understand the issues, the choices and the hierarchy of these choices,” insists Yves Lévi. However, if access to water is a national issue, it has different magnitudes depending on the region.
Because the situations vary greatly from one region to another, and sometimes even between two neighboring areas. “We must urgently develop a national strategy for thirty years, with national, regional and local levels”, recommends Yves Lévi, who campaigns for the use of “common sense”. Indeed, depending on the needs, the terrain, and many other local factors, all technical solutions are not equal in all situations.
This is why, beyond the technical solutions, it is important that everyone understands the terms of the debate. “There is absolutely a need for consultation and transparency”, insists Yves Lévi, who regrets that many words are used in the public debate without the meaning necessarily being understood. Thus, the notions of “crisis” and “shortage” are used by referring exclusively to the quantities available at a given time, without taking into account the withdrawals necessary, and the water that returns to the environment.
The health and ecological impacts of the solutions envisaged must also be taken into account, with more resources given to the authorities in charge of water health control. Finally, academics call for the use of objective language on technologies, with their advantages and disadvantages, to clearly define the cases in which they may or may not be useful, and above all to refuse simplistic solutions.
