Climate change disrupts the water cycle, and human activity exacerbates the shortage of fresh water. Tensions for control and monopolization of this vital resource are increasing. Similar to oil in the 20th century, water is becoming a source of conflicts. Can we find in the past, especially in regions with river cultures, devices that can help resolve tensions among different stakeholders?
The theme will be discussed over the next three forums in a dialogue between scientists: Bernard Mossé and Karl Matthias Wantzen.
Sequence 1 - The impact of human activity on the water cycle
Bernard Mossé: Can you give a quick explanation of the water cycle, highlighting the role of rivers in this system?
Karl Matthias Wantzen: The water cycle includes evaporation, cloud formation, precipitation, surface or subsurface flow, and finally the return of water to the oceans, often through rivers. In some cultures, such as in the Andes in South America, this cycle is compared to the cycle of life, with rivers representing the birth and death of souls. However, human activity disrupts this cycle, particularly through surface sealing, reducing floodplains of rivers, and deforestation.
BM: The negative impact of humans is often placed at the beginning of the industrial era. Can we say that human activity has been affecting this cycle for much longer?
KMW: Yes, but it is necessary to know where and on what scale. The large-scale damming of rivers results in the absence of sediments: the so-called "Delta" river mouths turn into "Beta" shapes due to erosion everywhere and in large quantities (only a third of major rivers can still flow freely). This is a product of the last century, and a catastrophe for the ecological functioning and support of bio-cultural diversity.
If we take, for example, the link between vegetation and water, what is called the "flying rivers," that is, evapotranspiration by plants, which produces a certain humidity in the local air: depending on the amount, it can have a very strong impact. For example, for the part above the Amazon, in South America, 15 to 20% of the rain depends on these "flying rivers". The destruction of these primary forests has reached a tipping point. Its continuation would be a catastrophe first for South America and for the entire planet.
Around the Mediterranean, deforestation of forests began with the Greek civilizations, perhaps even earlier with the Phoenicians, and then the Romans, to build their ships and fortresses. They also built dams and aqueducts, and polluted mineralization sites. This certainly had an influence on the water cycle and river flow, but with limited impact. Over the past centuries, and particularly since the industrial revolution, human impact on the water cycle has intensified, with urbanization, dam construction, and excessive resource extraction.
BM: For the UNESCO Chair on Rivers for which you are responsible, you connect environmental sciences with human and social sciences. The scarcity of freshwater, which is expected to worsen, is a source of tensions, even conflicts, among various stakeholders. What solution do you propose to resolve them? Can we find in the past, perhaps in regions with river cultures, mechanisms that allow resolving tensions among different stakeholders?
KMW: For me, the solution lies in my concept of "river culture." It is necessary to transform watersheds, which are the hydrographic basins that collect all the water falling in a region, into political territories. If you allow me this neologism, we must transform territories into "hydrotories," meaning "basins of responsibility." All humans and all nature within a watershed are subject to the same constraints and have the same interests. However, human territories often do not align with this geography. Rivers face a problem: they are long, so they cross multiple territories that often have a rounded shape. Beyond a certain length, rivers become sources of division between several territories. And that is a mistake. The river becomes a victim of territorialization. It is necessary to place the river in the middle of the territory, to build political landscapes around this hydrological reality.
BM: If I understand correctly, you believe that the interest of man is to model his actions on those of nature?
KMW: As long as our actions continue to disrupt the functioning of the landscapes, yes, absolutely. Our decisions on a basin - dam or water transfer between two watersheds - have an impact on the survival of crops, species, and the quality of current and future generations. What quality of life do we want for the future?
Are we going to damage it with a strategy of users that only focuses on the next 5 years, or do we want our children to have at least the same conditions as us, or ideally better conditions, regarding water abundance, pollution levels, the presence of biological species, etc.? If so, we need to change our behavior profoundly...
In the world, there are populations with traditional practices that are perfectly adapted to the rhythm of water, meaning to the variation in flow, between minimal flow and natural floods. But especially in Europe, there is this religion of feasibility and engineering that has ended up causing disproportionate impacts. It comes back to your first question: the Romans had already disrupted nature, but they still kept their activities below a certain threshold. Today, this threshold is exceeded. Rivers have been so altered that we are facing a vicious circle: the scarcer the resource becomes, the more greedy we become. It's the tragedy of the commons. We need to develop a shared responsibility. This is obviously very difficult, because humans, as a biological species, react to immediate threats. It is necessary to integrate future forecasts into present actions. And we need to convince the community that everyone should do their part, including the strongest individuals in competitive situations. This brings me back to the concept of responsibility basins: if we have a hydrological nation, we will act together, because we do not want to leave the poorest behind if we want this community to have a sustainable future. Even if it requires making sacrifices today, or abandoning certain practices, stepping out of one's comfort zone. This is the most difficult part: convincing people, especially those who benefit the most from the current situation. But it can work with a community based on negotiation, understanding the stakes, and respecting each other. I have found some examples around the planet, in South America, India, and Africa, and of course also in Europe. Often, unfortunately, the trigger for this community is a catastrophe. This is what happened in the Rhine Valley with a chemical accident in 1986: all the countries along the Rhine then endorsed the agreements that had been on the table for years.
BM: Yes, it's a parallel that can be drawn with mass crimes: consciences awaken when the tragedy has occurred.
KMW : Regarding disasters, one must be careful, because what is happening can be so strong that one may survive, but maybe not. The more precise question is: at what level of quality of life do we want to live in the future?
The catastrophe of Sarnen in Switzerland (the pollution of the Rhine by the water from the firefighters following the fire in a chemical factory) eliminated a large part of the fish in the river and cut off drinking water for several weeks. The problem extended all the way to the sea. With adjustments, the problem was more or less solved. However, with excessive deforestation of the river sources, without replanting, without protection, and with the construction of dams, the damages exceed the span of a human life: there are indeed solutions, but we will not see them. We are condemning future generations to live in water scarcity for several generations or forever. And this is the great responsibility of our generation today. We cannot just say "we need to educate the young better so they can do better." No, it is today that we must act.
Short biography
Karl Matthias Wantzen studied biology at the University of Constance, completed his PhD on Brazilian waters at the Max Planck Institute, and obtained his postdoctoral qualification on the topic of "Biodiversity and nature conservation of large rivers." For 8 years, he led an international cooperation project on the Pantanal in Brazil, the vast floodplain of the Paraguay River.
Since 2010, he has been a professor at French universities, first in Tours, and since 2023 in Strasbourg. In addition to a UNESCO chair "Rivers and Heritage," he also leads an interdisciplinary chair "Water and Sustainability" for the trinational university partnership "EUCOR- The European Campus".
More information at https://ites.unistra.fr/recherche/equipes/bise/karl-matthias-wantzen, https://www.unesco-chair-river-culture.eu/
Bernard Mossé Historian, Head of Research, Education, and Training at the NEEDE Mediterranean association.
Member of the Scientific Council of the Camp des Milles Foundation - Memory and Education, for which he was the scientific manager and coordinator of the UNESCO Chair "Education for Citizenship, Human Sciences, and Convergence of Memories" (Aix-Marseille University / Camp des Milles).
To go further
Wantzen K.M. (editor), River Culture, Life as a dance to the rhythm of the waters, Ed. UNESCO, 2023.
Here is the link: https://unesdoc.unesco.org/ark:/48223/pf0000382774
Wantzen, K. M. (2022): River culture: How socio-ecological linkages to the rhythm of the waters develop, how they are lost, and how they can be regained. The Geographical Journal, 00, 1–16. DOI: https://doi.org/10.1111/geoj.12476, free download
Here is the link: https://rgs-ibg.onlinelibrary.wiley.com/doi/epdf/10.1111/geoj.12476
Wantzen, K.M., Ballouche, A., Longuet, I., Bao, I., Bocoum, H., Cissé, L., Chauhan, M., Girard, P., Gopal, B., Kane, A., Marchese, M. R., Nautiyal, P., Teixeira, P., Zalewski, M. (2016): River Culture: an eco-social approach to mitigate the biological and cultural diversity crisis in riverscapes. Ecohydrology & Hydrobiology 16 (1): 7-18
http://dx.doi.org/10.1016/j.ecohyd.2015.12.003 free download