WatershedsoftheNorthernSlopeoftheMaciçodaTijuca

The north face of the Maciço da Tijuca, facing the plains of Tijuca and Inhaúma, holds an intricate hydrographic network that shapes the valleys nestled between its escarpments and spreads out over the lowlands toward Guanabara Bay. The Maracanã, Joana, Faria, and Timbó rivers have their headwaters embedded in the slopes of the massif, at altitudes ranging from 400 to 1,000 meters, and flow through free-running channels until they meet the urban grid, where they are confined into channels, sometimes straightened, sometimes buried underground beneath the asphalt.

The Maracanã River, the most emblematic of the group, rises on the steep slopes of the Floresta da Tijuca, among rocky cliffs covered by Atlantic Forest vegetation. In its upper course, it gathers threads of crystalline water that flow down the near-vertical face of Pedra da Mazomba, which frames the scenery of the Bairro da Usina, along with drainage lines that form small waterfalls and pools among gneiss boulders on the slope of Pedra do Conde. These are living stretches within the Tijuca National Park, where the water cycle recalls the history of deforestation, coffee farming, and reforestation that, in sequential historical moments, dominated all of its slopes. As it descends, the Maracanã loses its freedom, channeled through long urban stretches until it flows into the Canal do Mangue, at Praça da Bandeira, the former Saco de São Diogo, filled in by the "modernizations" of Mayor Pereira Passos. The change in water quality, habitats, and the ecological quality of the river stretches themselves is absurdly stark and sad. The radical paving of the lowlands, and even of many of the slopes, ensures an increase in surface runoff during heavy rains, and, increasingly, even smaller rains cause larger floods in the impermeabilized Praça da Bandeira. Acting only on the effect, the construction of retention pools invests our public money in something that could have been avoided through urban planning.

Image description: This is an aerial photograph of an urban area. On the left, we see a series of buildings of different heights, with roofs mostly in shades of orange and beige. In the center, there is a large traffic thoroughfare with several lanes of moving cars. On the right, a large building with a circular dome stands out, possibly a stadium or an events center, with a light-colored metal structure. Along the streets, there are scattered trees and some green areas.

Maracanã River, channeled near Ginásio Gilberto Cardoso (Maracanãzinho)

The Joana river, a direct tributary of the Maracanã, does not escape this same process. Its headwaters come from the Vale do Elefante, a suspended valley at the foot of Pico Andaraí Maior and above Pico do Perdido, where the Rio Perdido is born, in Grajaú. Added to these waters are the headstreams of the Rio do Urubu, also in Grajaú, where one of the largest boulder deposits of the Maciço da Tijuca is found. Today, these headstreams are protected by the union of the Conservation Units of the Tijuca National Park and the Grajaú Reserve, a state reserve, though managed by the municipality. Deforested and covered by Guinea grass until the mid-1980s, these headstreams were the setting for several reforestation projects, which, thanks to the effort of the Forestry Engineers and workers of the Mutirão Reflorestamento Project, restored, through this long-standing effort that remains active to this day, the forest fringe that now shades them.

Image description: This is a photograph of a city with a panoramic view. From left to right, we see a series of multi-story residential buildings, some with red roofs. In the center, there is a park with green trees. On the right, more buildings extend to the horizon. In the background, we see mountains covered with green vegetation. The sky is partly cloudy.

Bend of the Rio Joana, channeled along its lower course, by Avenida Professor Manoel de Abreu, parallel to the tree-lined Boulevard 28 de Setembro.

Image description: This is a photograph of an urban drainage canal. On the left, we see a concrete wall with some decorative elements and a tree. On the right, there is another similar wall, also with decorative elements and a tree. In the background, there is a street with cars and residential buildings. The canal is filled with water, which flows slowly. In the lower right corner, there is some small green vegetation.

Rio Joana, canalized along its upper course, by Rua Maxwell.

Image description: This is a photograph of a mountainous landscape. From left to right, we see a series of hills covered by dense green vegetation. Moving further to the right, the vegetation becomes sparser, revealing patches of exposed soil. In the background, we see a city with buildings of various sizes and colors, arranged irregularly. The mountains in the distance form a far-off horizon, with some higher peaks. The sky is partly cloudy, allowing sunlight to illuminate the landscape.

Sources of the Rio do Urubu in Grajaú, tributary that forms the Rio Joana, an affluent of the Rio Maracanã.

Image description: This is an aerial photograph of a mountainous landscape. On the left, we see a darkened rock with streaked textures. In the center, there is a green hill covered by dense vegetation. At the top of the hill, we see tall, thin electrical structures. On the right, more green hills stretch to the horizon, where other electrical elements are located. In the background, we see more hills and a distant city. The sky is light blue with some white clouds.

Mosaic of reforestation areas of different dates and shapes, representing the effort of the Mutirão Reflorestamento project in Grajaú, at the foot of Pico do Perdido

Image description: This is a photograph of a waterfall in a natural setting. On the left side, we see a fallen tree, while on the right there are rocks covered in green moss. The center of the image features a small waterfall cascading over these rocks, forming a calm pool at the bottom. The water is clear, revealing the rocky bottom.

Mãe D'água Waterfall in Grajaú, Rio Perdido, a tributary of Rio Joana

Special mention should be made of the Mãe D'água waterfalls and their sequence of pools and falls upstream, which form, behind the Pico do Perdido, a trail of exuberant beauty. The Rio Joana thus plays an important role in water retention and in maintaining its headwaters, but upon reaching the urban grid, it runs disgracefully through a narrow concrete channel along Avenida Maxwell to the Maracanã stadium. There it joins the Rio Maracanã, and part of its flow is diverted to São Cristóvão, emptying into the dense Canal do Mangue toward the port area.

Further north, two founding rivers of Rio's history form a large drainage basin for Guanabara Bay: the Faria and Timbó rivers, today tributaries of the Fundão Canal. However, before the landfill works, they were two rivers that discharged their waters into the same inlet of the Saco de Inhaúma, an arm of the sea that reached inland to almost where the neighborhood of Maria da Graça is located today. The entire region, today, toward Guanabara Bay, holds neighborhoods built on successive landfills, all the way to the Favela da Maré, not by chance bearing that name.

Image description: This is a photograph of a cityscape at dusk. On the left side, we see a modern building with a brown façade. In the center, there is a road with many cars in motion. On the right, there is a river cutting through the city, with trees along its banks. In the background, we see a densely populated city and a mountain range on the horizon. The sky is light blue with scattered clouds.

Fundão Canal

The Faria River rises on the northern slope of the Maciço da Tijuca, forming the boundary with the Vale do Elefante, mentioned earlier, and collecting river contributions from the entire Serra dos Pretos Forros, where many springs converge toward the lowland known as Grande Méier, encompassing the elevations of the Serra do Engenho Novo as far as Benfica.

Due to its size, the drainage basin converges several streams, which cross Largo do Encantado, Engenho de Dentro, and Jacaré, running through urbanized stretches already at low gradient. Like its tributaries, the Faria has already been suffering from the channeling process along its middle and lower courses, being captured by engineering works that alter its river landscape all the way to its mouth.

Its watershed contributor, the Timbó River, springs from small isolated hills, from the Morro do Juramento and from the slopes of the entire Serra da Misericórdia. There are several small watercourses that quickly reach the flatland of the Inhaúma lowlands. Its waters run through small steps in the terrain, often over rocky outcrops, which were historically exploited by mining. Soon after, the Timbó River reaches the lowlands and is channeled between densely occupied neighborhoods. The spatial division of the occupation plan for Rio's suburbs ensured dense urbanization with beautifully fronted houses from the early twentieth century. With large backyards full of fruit trees, such houses accommodated the working-class families of the factories recently built during Rio de Janeiro's industrialization process. The train line and the large railway stations promised a good quality of life in these neighborhoods. The good life of Rio's suburbs came with the settlement of many immigrants, from Cachambi and Maria da Graça to Penha and Olaria, occupying this whole lowland area up to the landfills of the Saco de Inhaúma, today replaced by the Canal do Cunha, which joins the Faria and Timbó Rivers into a single outlet at the Canal do Fundão.