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CLIMATE CHANGE
The importance of respecting the natural cycle of water to achieve water security
Almost two months after the tragedy in Southern Brasil, in an exclusive article for the G20 Brasil website, Carlos Saito— a Biologist specialized in environmental management and Professor at the University of Brasília (UnB), explains the natural cycle of water and its importance for the preservation of ecological balance. Professor Saito believes that discussions about human intervention in nature must continue in order to prevent new catastrophes. He also highlights some environmental laws that are thought to hinder economic development, a perspective that must be reconsidered in the face of tragedies with so many human and material losses. Read the full article.
The 2024 floods in the Brazilian state of Rio Grande do Sul are considered the greatest tragedy associated with meteorological/climate events and hydric resources in the history of Brazil— not so much for its death toll but for the extension of affected areas, the number of dislodged people, and the costs for the reconstruction of cities and roads. Amid the pain of those affected and the astonishment of those who never imagined such a tragedy as possible, we must reflect on the origins of the disaster, aiming to avoid its repetition.
First, we must recall the concept of water security, which corresponds to a population's capacity to ensure access to adequate amounts of water of acceptable quality to sustain the means of subsistence, human well-being, and economic development; to protect against both pollution and water-related disasters; and to preserve the ecosystems in an environment of peace and political stability (UN-Water, 2013).
Environmental laws that seek to ensure the required protections through permanent preservation areas have always been perceived by the economic sector as cruel impediments to development, but the time may have come to understand why they were established.
This concept takes us back to the issue that the affected populations went through, which has the search for potable water as one of the main challenges after the floods: access to water, in adequate quantities and quality, regularly and constantly, at an affordable cost. But it also takes us back to the ecosystems that were either not preserved or have now been affected.
Another important concept is mitigation, understood as an action towards reducing the level of risk posed by a threat, or one of the scenarios visualized for a threat, making it less grave, dangerous, or harmful. This concept has been frequently applied when discussing the impacts of climate change, meaning the prevention or reduction of greenhouse effect emissions into the atmosphere or the promotion of an increase of forested areas that can capture carbon from the atmosphere, in the hope of reducing the impacts of climate change. These concepts help us think of mitigation measures that could have reduced the occurrence of the disaster, ensuring hydric security.
Gran production (the basis of the state's economy) has been grounded on the removal of native vegetal coverage, even on the sides of watercourses, which favored the rise of water levels at times of intense and extreme rainfall. Trees can soften the impact of raindrops, making each drop of rain run through the leaves, branches, and trunk so that, when they reach the ground, they can still infiltrate through the contact between the soil, the tree, and its roots. Without the trees, water hits the soil directly and runs to the rivers taking sediments, parts of the soil, which are deposited on the riverbeds, reducing their depth.
The torrent also erodes the riverbanks as it flows into the river, further increasing the sediments that silt up the riverbed. Without trees, then, water runs faster to the lower parts, filling the rivers and causing floods. Environmental laws that seek to ensure the required protections through permanent preservation areas have always been perceived by the economic sector as cruel impediments to development, but the time may have come to understand why they were established.
In urban areas, soil impermeabilization equally contributes to accelerating the water cycle. The rain hits the surface covered in concrete and runs fast to the lower parts, whether on public roads or through storm water drainage systems. Frequently, to worsen the problem, storm water drainage systems head straight into rivers, without a mechanism to slow down the force of the water that comes into the collection network. This water from the pipes hits the riverbanks at the discharge points and increases erosion, taking more sediments into the river. Neighborhoods with precarious infrastructure also increase the transportation of mud and sediments into the river.
Cities have been growing in a disorderly manner, without planning. Wide green spaces such as urban woods scattered through the urban net (at least one in each neighborhood) can promote rain infiltration while also serving as leisure areas and community meeting spaces. They could be built at a lower level in relation to the living spaces to receive water from the rain coming from nearby streets, flooding during torrential rains and allowing time for water infiltration, preventing it from immediately causing the water levels to rise in the rivers.
Flooding, climate change, and human action
In this sense, these events are due to the way we have been using soil coverage. But would they have anything to do with climate change? Yes, these floods are related to climate change, equally caused by humanity. We have demonstrated how changes in the way we use and cover the soil accelerate the water cycle. However, we have only described part of the cycle, from when the water falls from the atmosphere in the form of rain until it flows through the rivers to the lower parts of the watershed, eventually reaching the coast. To complete the cycle, there is also the part that corresponds to the water’s return to the atmosphere through evaporation. When temperatures rise (in the air and water), water evaporation increases. If the global warming caused by greenhouse effect gases increases the planet’s temperatures, there is bound to be more evaporation. And the larger the amounts of evaporation from rivers and oceans, the more water is taken to the atmosphere, which returns in the form of more intense rainfall.
A reminder: social participation must be based on scientific rationality. The path followed by water is a natural one, the water cycle does not change. What we are doing is accelerating its circulation and the volume that circulates in each stage of the cycle across time. This is why we have been seeing extreme events with more frequency, more intensity, and repetitions in ever-shorter intervals.
It is high time we rethink the ways we occupy space. The scientific sphere and global and national technical institutions have much to contribute, bringing guidance to promote a world with more water security. For example, in the year 2000, the Global Water Partnership (GWP) developed a platform with various tools for hydric resources integrated management: the Toolbox currently has hierarchically organized tools translated into several languages, accompanied by explanatory texts and case studies (https://iwrmactionhub.org/learn/iwrm-tools).
In addition to paying attention to science and learning through the evaluation of experiences, we must also listen to the different stakeholders engaged with the issue through participation processes. In this sense, the initiative by Brasil’s Ministry of the Environment and Climate Change to organize the 5th National Environmental Conference (5ª Conferência Nacional do Meio Ambiente - CNMA), with preparatory stages to be held in municipalities and states and free conferences aiming to debate the theme of “Climate Emergency: the challenge of ecological transition”. This will be yet another opportunity to collectively rethink the country and avoid disasters. It will also be a space to reassess the Hydric Security National Plan (Plano Nacional de Segurança Hídrica) and its primary focus on construction and infrastructure, to the detriment of environmental and ecosystem aspects. Moreover, the weight attributed to water policies inside governmental actions and structures.
A reminder: social participation must be based on scientific rationality. The path followed by water is a natural one, the water cycle does not change. What we are doing is accelerating its circulation and the volume that circulates in each stage of the cycle across time. This is why we have been seeing extreme events with more frequency, more intensity, and repetitions in ever-shorter intervals. Thus, we must think of strategies to ensure that the water fulfills its cycle slower, as it used to. We must learn from nature, not challenge it or fight against it. And well-thought-out mitigation actions can help us seek a country with more water security.
Carlos Hiroo Saito is a professor at the University of Brasília, affiliated with the Department of Ecology in the Institute of Biological Sciences, and at the Center for Sustainable Development at the same university. He has also twice held the presidency of the Global Water Partnership-South America (GWP-SAM), and currently chairs the Brazilian section of the same GWP network.