The Piracicaba River () is a watercourse of Minas Gerais state in southeastern Brazil. It is a tributary of the Doce River. The river rises at an altitude of , at one of the vertices of the Caraça mountain range, in the São Bartolomeu district. It runs for 241 km to its mouth on the Doce river, between Ipatinga and Timóteo. Its main tributaries are the Prata, Peixe, Maquiné and Santa Bárbara rivers and the Turvo stream. The basin covers of drainage area and a total of 21 municipalities.
The first settlements along the river's banks began at the end of the 17th century during the gold mining boom in Minas Gerais, which led to the foundation of settlements in Ouro Preto and Mariana. Although mining was developed in the Iron Quadrangle in the following centuries, urbanisation in the basin area was only consolidated in the 20th century, after the EFVM was leased. The railway, near the river, led to the emergence of urban centres. At the same time, the availability of forests for timber extraction and water supply from the river encouraged the installation of metallurgy companies in João Monlevade and the current Steel Valley, driving demographic and economic growth.
Thus, the Piracicaba River crosses a region with a notable presence of industrial activity, especially mining and steelmaking, supplying some of the local industrial plants and hydroelectric power stations. On the other hand, the riverbed suffers severely from siltation, deforestation, the proliferation of eucalyptus monoculture, low coverage by riparian forests and the receipt of untreated urban effluents, making it one of the most degraded tributaries of the Doce River.
Etymology The most popular version for the origin of the river's name is that the term "Piracicaba" was borrowed from Tupi-Guarani and interpreted as "place where the fish stop". This would be an allusion to the significant number of small falls found in some sections of the riverbed, especially in the Antônio Dias region, which disrupt the fish traffic. This argument also explains the origin of the São Paulo Piracicaba River's name. Another popular version states that "Piracicaba" in Tupi-Guarani means "river without fish", but the application of this interpretation to the Piracicaba River is questionable, given that in the past it was a river with plenty of fish.
History Exploration and mining The region between the mouths of the Piracicaba and Manhuaçu Rivers, i.e. between Ipatinga and Aimorés, was originally inhabited by the Aimoré peoples. Attempts to explore the Doce River Valley in search of mineral riches began in the 16th century, but were unsuccessful, which ended up delaying the settlement of the area. The expedition of Sebastião Fernandes Tourinho (1573) entered the course of the Doce River and some of its tributaries, calling the region at the mouth of the Piracicaba River the ‘Green Valley’, due to the dense forest.
Towards the end of the 17th century, the discovery of gold at the headwaters of Das Velhas and Piracicaba rivers, in Ouro Preto, encouraged expeditions of bandeirantes from São Paulo to explore those areas and then explore downstream. The search for gold led to the establishment of settlements in Ouro Preto and Mariana. In the early 18th century there were also settlements on the Piracicaba river banks in Catas Altas, Santa Bárbara, Nova Era (formerly São José da Lagoa), Rio Piracicaba (formerly São Miguel do Rio Piracicaba) and Antônio Dias. In addition to mineral extraction, cattle ranches and small factories could be found along the river. Mining was Brazil's main economic activity in the 18th century, but its rise led to the first environmental impacts on the rivers in the affected areas, including the Piracicaba.
Colonisation progress
The Rio Doce Valley used to be on a route for the precious stones mined in the central region of Minas Gerais, linking the Royal Road in Diamantina to the coast of Espírito Santo for export. As a result, the royal crown banned settlement and new roads in the region to prevent the gold from being smuggled down the Doce River and its tributaries, such as the Piracicaba. In an attempt to keep outsiders away, the lands were described as having dense vegetation and venomous animals, with a predominance of the ferocious Aimoré. However, settlement was authorised in 1755, after Minas Gerais experienced a decline in gold production. Despite the decline in gold availability, the mineral diversity fuelled the maintenance of mining activity in the Ouro Preto region, including in the Piracicaba riverbed, over the following centuries.
Once settlement was authorised, the Aimoré were massacred so that outsiders could conquer the land. Under these circumstances, native attacks on settlements became constant, forcing the colonists to abandon their farms and livestock. The natives, in turn, faced military punishments, such as the expedition of Luís Diogo Lobo da Silva in the 1760s, then governor of the Captaincy of Minas Gerais. The administrator and his troop of 150 armed men navigated the rivers Piracicaba and Doce as far as Cuité (now Conselheiro Pena) in an act of repression against the natives. In the early 19th century, "barracks" were built to reinforce protection of the settlers. Despite the ban on attacks on natives in 1831, the original population was almost extinct, which served as an encouragement to colonisation. However, this process was relatively slow. It's worth noting that in 1821, the only settlement downstream of Antônio Dias before the mouth of the Piracicaba River was Alegre, now Timóteo.
It wasn't until the construction of the Vitória-Minas Railway (EFVM) that occupation of the region began to pick up. The railway started in Vitória, Espírito Santo, and its initial objective was to reach Diamantina, but to transport iron ore the focus was shifted to Itabira when work was already underway. The establishment of railway stations resulted in a number of urban centres throughout the first half of the 20th century. The railway follows the course of the Doce and Piracicaba rivers for the majority of its length, resulting in increased population growth on the banks of these rivers. As a result, environmental transformations in the region intensified. This process was aggravated from the 1930s onwards, when large areas of native Atlantic Forest in the basin were deforested for the extraction of timber and the production of charcoal to supply the Belgo-Mineira industrial complex in João Monlevade. The exploitation was managed from Calado, now Coronel Fabriciano, located on the banks of the Piracicaba River. The same company also used the river to generate the energy that powered the plant.
Urbanisation and environmental degradation The existence of a railway, watercourses and forests for timber extraction were decisive factors in the establishment of Acesita in Timóteo in 1944 and Usiminas in Ipatinga, near Coronel Fabriciano in 1956. In 1951, to provide the company with electricity, Acesita built the Sá Carvalho Hydroelectric Power Station, located on the Piracicaba River in Antônio Dias, the largest hydroelectric power station in Minas Gerais at the time. The construction of the steel mills led to sudden urban and population growth in the region, which was no longer known as Vale Verde and was renamed Vale do Aço (Steel Valley). This resulted in the construction of workers‘ villages in the companies’ towns, infrastructure and increased deforestation.
Reports from long-time residents indicate that fish were abundant in the Piracicaba River during the 20th century. Near the old Calado station in the centre of Fabriciano, for example, fishermen would gather every afternoon and leave with bags full of fish. On some occasions, more than 300 people would gather near the river. In Antônio Dias, fishing yielded traíras, piaus, piabanhas, surubins, cascudos and freshwater lobsters. The river was also used for transport and leisure by the riverside towns. Records indicate that hundreds of evangelical church members were collectively baptised in the waters of the riverbed in Coronel Fabriciano until the early 1970s.
Throughout the second half of the 20th century, the urban centres of João Monlevade and the Steel Valley kept growing due to industrialisation, as well as the expansion of eucalyptus monoculture to meet the needs of the power plants. Consequently, the dumping of urban and industrial effluents into the waters was intensified, a situation aggravated by the construction of new hydroelectric power stations along the river, extensive land use and mining. Flooding was also a major problem thanks to unbridled occupation of risk areas. On the other hand, there have been some efforts to reduce degradation, such as the implementation of riparian forest along the river mouth by Usiminas in the 1990s; the creation of the Piracicaba River Basin Committee (CBH) under the State Water Resources Policy on 17 February 2000; and the construction of wastewater treatment stations in some cities. However, the situation remained critical in the first decades of the 21st century, due to siltation caused by mining, pollution and severe droughts.
Geographical aspects
Drainage and climate
The Piracicaba River rises on one of the peaks of the Caraça mountain range at an altitude of metres, in the district of São Bartolomeu, which belongs to Ouro Preto. It runs for a total of 241 kilometres to its mouth on the left bank of the Doce River, of which it is one of the main tributaries, between the municipalities of Ipatinga and Timóteo, at an altitude of 210 metres. For most of its course, the river flows in a north-easterly direction. Its drainage basin is part of the Doce River Basin and covers of drainage area, which is made up of the sub-basins of the Peixe and Santa Bárbara rivers on the left bank and the sub-basin of the Prata river on the right bank. Other major tributaries include the Maquiné and the Turvo rivers. In addition to these major rivers, the Piracicaba River is fed by about 100 streams and creeks.
The climate in the basin transitions between tropical (Aw, according to the Köppen-Geiger climate classification), hot-summer mesothermal (Cwa) and mild-summer mesothermal (Cwb), and is influenced by continentality and altitude. During the winter months, the presence of the South Atlantic High favours the dominance of high pressure, preventing humidity from rising and thus creating the dry season. This period also includes the intrusion of polar air masses, which make it difficult for temperatures to rise and squall lines to form. In summer, on the other hand, temperatures rise and the influence of tropical instabilities creates the rainy season. The headwaters region, with the Cwb climate classification, has the highest average precipitation due to the incidence of orographic rainfall, reaching 1,500 millimetres (mm) a year. The Cwa classification, on the other hand, is found in most of the basin, in its central area. The Aw climate is recorded in the Steel Valley, at the mouth of the Piracicaba River, accompanied by the lowest average annual rainfall, which is 1,000 mm.