São Francisco River
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What is the São Francisco River?
The São Francisco River is a major river in eastern South America and the largest river entirely within Brazil. It is the fourth-longest river system on the continent, stretching approximately 1,811 miles (2,914 kilometers).
The São Francisco River rises at about 2,400 feet (730 metres) above sea level on the eastern slope of the Serra da Canastra in southwestern Minas Gerais state. Flowing north through Minas Gerais and Bahia, it curves northeast, forming a border between Bahia and Pernambuco, and finally between Sergipe and Alagoas. The river ends at its mouth on the Atlantic Ocean, roughly 60 miles (97 kilometers) northeast of Aracaju.
Known as the "river of national unity," it serves as a vital link between Brazil's coastal and inland regions and between the northeast and the south. The river is also an important source of hydroelectric power and irrigation for eastern and northeastern Brazil. The São Francisco basin covers about 243,700 square miles (631,200 square kilometers).
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Where is the São Francisco River located in Brazil?
The São Francisco River is a major river in eastern South America and the largest river entirely within Brazil. It rises at about 2,400 feet (730 metres) above sea level on the eastern slope of the Serra da Canastra in southwestern Minas Gerais state. The São Francisco River flows for more than 1,000 miles northward across the states of Minas Gerais and Bahia. The river turns eastward to the Atlantic. The São Francisco River basin covers more than 249,000 square miles (645,000 square km) in eastern Brazil.
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How long is the São Francisco River, and which major states does it flow through?
The São Francisco River, at 1,811 miles (2,914 kilometers), is the fourth-largest river system in South America and the largest wholly within Brazil.
The river flows northward through the states of Minas Gerais and Bahia, where it enters the Sobradinho Reservoir. It then curves to the northeast, forming a border between Bahia and Pernambuco. In its lower section, the river forms the border between Sergipe and Alagoas before reaching its mouth on the Atlantic Ocean.
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Why is the São Francisco River important for the regions it passes through?
The São Francisco River is important to the regions it crosses because it serves as a vital line of communication between Brazil’s coastal and western areas and between the northeast and the south. Additionally, the river is a source of hydroelectric power and irrigation for eastern and northeastern Brazil. The river is navigable for small steamers for over 1,000 miles, making it an important link between the mining districts and roads that lead north and east.
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What kinds of plants and animals live in and around the São Francisco River?
The Sāo Francisco River basin is home to a diverse array of plant and animal life.
Plant Life
The upper, wetter regions of the basin feature savannas and mixed evergreen and deciduous forests, including hardwoods like jacaranda, Brazilian cedar, and vinhatico. Cacti, aloes, and vanilla plants also thrive here. The middle basin has caatinga vegetation, with thorny forests of catingueiras and juremas trees, spurge, and barriguda trees. Bromeliads and cacti make up the undergrowth. Useful species include caroa, castor oil plant, and cashew and rubber trees. The falls zone supports drought-resistant brush and grasses, carnauba and babassu palms, cacti, rock roses, and rhododendrons. The lower Sāo Francisco has tropical semi-deciduous forests.
Animal Life
Animals in the Sāo Francisco basin include marsupials, rodents like the capybara, skunks, gato de mata (a small wild cat), titi monkeys, and armadillos. Birds include tinamous, doves, parrots, yellow finches, and vultures. Smaller birds like hummingbirds and sabias are also present. The river's fish, such as robalo, sardines, pocomó, and sarapó, are important for food. Manatees and sharks inhabit the river mouth.
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How do people use the São Francisco River for transportation, farming, and electricity?
The S\u00e3o Francisco River serves various crucial functions for the people of eastern and northeastern Brazil. For transportation, small steamers navigate over 1,000 miles of the river, connecting inland areas to coastal regions.
Along the riverbanks, vazante agriculture utilizes shallow waterbeds to cultivate crops such as cassava, corn, beans, and melons. Additionally, truck crops are grown on the riverbanks.
The river's hydroelectric potential is a vital resource, with power-generating centers at Paulo Afonso Falls and Três Marias Reservoir. These facilities, along with other hydroelectric plants on the river, supply electricity to coastal cities. The river basin is also an important source of irrigation water, with large storage dams and reservoirs.
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São Francisco River, major river of eastern South America. With a length of 1,811 miles (2,914 kilometres), it is the fourth largest river system of the continent and the largest river wholly within Brazil. The São Francisco has been called the “river of national unity,” for it long has served as a line of communication between Brazil’s maritime and western regions and between the northeast and the south. The river is named for the 16th-century Jesuit leader St. Francis Borgia (São Francisco de Borja). It is an important source of hydroelectric power and irrigation for eastern and northeastern Brazil. The São Francisco basin occupies some 243,700 square miles (631,200 square kilometres).
Physical features
Physiography
The São Francisco River rises at about 2,400 feet (730 metres) above sea level on the eastern slope of the Serra da Canastra in southwestern Minas Gerais state, about 150 miles northwest of the city of Belo Horizonte. The river flows for more than 1,000 miles northward across the states of Minas Gerais and Bahia, through the extensive Sobradinho Reservoir, to the twin cities of Juàzeiro and Petrolina. In this stretch the river receives its main left-bank tributaries—the Paracatu, Urucuia, Corrente, and Grande rivers—and its main right-bank tributaries—the Verde Grande, Paramirim, and Jacaré.
About 100 miles below Petrolina, the São Francisco begins a great curve to the northeast and enters a stretch of rapids and falls 300 miles long. In this section the river forms the border between the states of Bahia to the south and Pernambuco to the north. The upper rapids are navigable during periods of high water, but below Petrolina the river is impassable. The broken course—during which the São Francisco receives the São Pedro, Ipueira, and Pajeú rivers—culminates in the great Paulo Afonso Falls. At the top of the falls, the river divides suddenly and violently and cuts three successive falls through the granite rocks for a total drop of about 275 feet. Below the falls the river flows about 190 miles to its relatively narrow mouth on the Atlantic Ocean, about 60 miles northeast of Aracaju. In its lower section the São Francisco is joined by the Moxotó River and forms the border between the states of Sergipe to the south and Alagoas to the north.
Climate and hydrology
The lower river basin is largely a tropical semidesert, and the climate generally is hot and dry. The average maximum temperature for the region is 92° F (33° C) and the average minimum 66° F (19° C). The highest temperature recorded is 107° F (42° C). The prevailing winds are from the southeast, east, and northeast. Rainfall is deficient over most of the area, and drought is frequent. Average annual precipitation measures 20 to 40 inches (510 to 1,020 millimetres) in most of the middle basin and 40 to 80 inches in the headwaters region and below the Paulo Afonso Falls; most of the falls zone receives less than 20 inches annually, and a small portion receives less than 10 inches. Precipitation occurs during the summer months (December to March), while the rest of the year—the winter season—is dry.
Because the São Francisco River flows through the driest region of Brazil, it is subject to seasonal changes in water level of up to 30 feet. Most of its tributaries run dry during the dry season. Until the river was dammed at Juàzeiro, the riverbed upstream from there would vary from a narrow channel during drought periods to a much wider channel during the rainy season; the Sobradinho Reservoir now holds water throughout the year, although its level can vary considerably.
Plant life
The upper (southern), relatively wet part of the basin is covered with savanna (grassland with patches of trees), called cerrados, and with forests of mixed evergreen and deciduous trees. Hardwoods include the jacaranda, Brazilian cedar (cedro), and vinhatico; cochineal cactus, aloes, and vanilla plants also grow there. Characteristic of the middle river basin is caatinga vegetation (from the Tupí-Guaraní word meaning “white forest”), an area of stunted, often thorny forest. Among the dominant tree species are the leguminous catingueiras and juremas, members of the euphorbia (spurge) family, and the barriguda tree (a palmlike tree of the Bombacaceae family); bromeliads (plants with basal, often spiny leaves) and a wide variety of cacti constitute the undergrowth. Economically useful species include the caroa, used for its fibres; the castor oil plant; oil, carnauba, and date palms; and cashew and rubber trees.
The falls zone lies in the dry Brazilian interior, known as the sertão. The small amount of rainfall in the area permits the growth of only xerophytic (drought-resistant) brush and grasses. The dry forests of the hilly uplands support carnauba and babassu palms and such plants as the cactus, the rock rose, and the rhododendron. One unusual plant of the sertão region is the evergreen aveloz, which can grow to heights of 15 to 20 feet and is used as a hedgerow to mark field boundaries. Underground water in the region often is too saline for irrigation or drinking.
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The lower São Francisco flows through a floodplain of fine silt soils, and tropical semi-deciduous forest thrives there. Most of the original vegetation that grew along the river, however, has been cleared for agriculture.