The crisis in the Cantareira System, which supplies water to 9.86 million people in the São Paulo metropolitan area and the countryside, is a concrete example that water supply may be also compromised in others cities in Brazil. Even though we have an optimistic view, the last episodes of draught in the Southeast and the South, which left reservoirs in these regions at critical levels, clearly show that there is a need for urgent implementation of conservation actions towards the maintenance of water resources in the country.
According to the Brazilian Atlas of urban water supply, which was published by the Agência Nacional de Águas (ANA — National Water Agency) in 2010, the total capacity of the supplying systems which are installed and in operation in the country was approximately 590 cubic meters per second four years ago, near the maximum demand of water at the time, which was approximately 540 cubic meters per second. This data shows that many of the units were working at the maximum limit of their operational capacity, and the Southeastern region represented 51% of the installed water producing capacity in the country.
Currently, the Southeast’s two largest metropolitan areas — Rio de Janeiro and São Paulo — have their water supply guaranteed because there is a great transference of water from springs located in watersheds nearby. The capital of the state of Rio de Janeiro, the Paraíba do Sul River watershed is used; while São Paulo is served by the watershed comprising the Piracicaba, the Capivari, and the Jundiaí rivers. These watersheds are responsible for the greatest part of the water supplied to the Guandu (state of Rio de Janeiro) and Cantareira (state of São Paulo) systems. Both sources are becoming saturated because they supply hundreds of thousands of people, generating water consumption that is much greater than the producing capacity of these watersheds. Thus, the risk is imminent of the consumers opening their taps and not see any water flowing from them.
We cannot blame, however, the excessive consumption or the misusage of water by the population for the supply crisis. It would be naïve to do so, for the issue is much more complex: it ranges from the lack of public policies encouraging the protection of springs to the deforestation of natural areas, which alters the water cycle and the rain regime in the regions where they once predominated.
It is necessary to evaluate the water cycle in a global manner: the loss of native vegetation areas in all the country’s biomes affects water availability not only at the local level, but also in distant regions. The Cerrado, for instance, is known as Brazil’s “water reservoir,” because it hosts eight of the country’s twelve watersheds and presents a high concentration of sources of the rivers that supply water to other Brazilian regions. In the case of Amazonia, there is the “air rivers” phenomenon, great masses of water vapor that are formed over the Atlantic Ocean and increase in volume by incorporating moisture from the rainforest. Carried by air streams to the South of the country, they are important for the formation of rain in several regions. Therefore, deforestation in Amazonia, which had decreased during four years, started increasing again in 2013 and might reduce rainfall in other regions.
Natural areas have great importance in the regulation of water resources. Without them, water does not perform its natural cycle, which includes evaporation, cloud formation, and rainfall on the sources of the rivers that supply water to the country’s watersheds, causing imbalance.
This is the situation at the Cantareira System, which is considered one of the world’s greatest water-producing systems. It is comprised of six reservoirs that are linked by 48 kilometers of tunnels that take advantage of the uneven terrain and the accumulation of water to form reservoirs. The rivers that feed the reservoirs in the system are the Jacareí and the Jaguari rivers — whose sources are located in Minas Gerais — plus the Cachoeira de Piracaia, Atibainha, and Juqueri rivers, whose sources are in São Paulo. There has been little rainfall in the sources of these rivers, even during the flooding season, which spans from November to March in the Southeast.
The below-average rainfall has decreased water flow in the rivers that supply the Cantareira System, so the levels of the reservoirs started to decline fastly. The decrease in water availability has resulted in a crisis of water supply to the population.
So, what should be done in face of this grave situation? Governments, at all levels — federal, state, and municipal — need to seek mechanisms to improve water management and guarantee water security. This concept represents the population’s right to access water of quality and quantity enough to guarantee its living and well-being, and the socio-economic development of the country.
In Brazil, the formation of a strong alliance is needed between several sectors of society — the private initiative, NGOs, the population in general, and government — as part of a global effort to protect natural resources. A protection that includes the creation and implementation of Protected Areas, which are fundamental to guarantee the conservation of natural resources and the environmental services supplied by these areas, amongst them there is the production of water of quality and in adequate amounts.
Since agriculture plays an important role in Brazilian economy, in regards to water consumption, this sector is ranked first, being responsible for 70% of the country’s water consumption (20% of the water is used by industry, and 10% by the population in general). For this reason, it is extremely important to protect riparian forests and river sources in rural properties as well, preventing pollution and siltation and ensuring that the river banks remain covered by vegetation, so that water slowly infiltrates the soil and is able to regularly complete its cycle. Within this context, it is important that legal reserves and Permanent Protection Areas (PPAs) are maintained, with the environmental role of conserving water resources and maintaining the ecological processes.
It is about time all sectors in society are aware that the problem of scarcity of water is not in São Paulo alone — which is currently the most serious. Otherwise, our lack of attention might be the last drop. The current challenge is how to guarantee water supply to the biggest Brazilian cities during the next years, since a growth in population is expected and, consequently, an increased demand for water. Urgent investments are necessary for the adequation of the water-supplying systems, especially in the Southeastern region, and the planning for an optimal use of the water sources. Additionally, the protection of natural areas is a sine qua non condition, for the quality and quantity of water produced by nature dependo n the maintenance of the native vegetation.