Trancão

Trancão
Course of the Rio Trancão
Data
location	Lisbon District (Portugal)
River system	Tagus river
Drain over	Tagus  → Mediterranean
muzzle	Mar da Palha (mouth of the Tagus River) Coordinates: 38 ° 47 ′ 46 "  N , 9 ° 5 ′ 24"  W 38 ° 47 ′ 46 "  N , 9 ° 5 ′ 24"  W.
Mouth height	0  m
length	23 km
Small towns	Sacavém
View of the Rio Trancão in Sacavém ; in the background is the Auto-Estrada do Norte (A1)

The Trancão or Rio Trancão (formerly Rio de Sacavém , river of Sacavém ) is a small river in Portugal . It stretches for about 23 km through the Lisbon district and flows into the Tagus .

course

The Trancão has its source in the Mafra district , where it flows west through the municipalities of Venda do Pinheiro and Milharado and then enters the Loures district , municipality of Bucelas .

In Bucelas, the river changes direction to the south and crosses the municipal area of São Julião do Tojal . It then forms the natural border between the municipalities of São João da Talha and Bobadela , which are to the east and north of the river, and Unhos and Sacavém , which are to the west and south. Shortly before it flows into the Tejo , the river makes another bend in a westerly direction.

Tributaries

The Trancão has the Ribeira das Romeiras as a tributary on its upper course in Bucelas . At the border between Unhos and São João da Talha the Ribeira da Póvoa (also called ribeira de Frielas) flows, which in turn arises from the confluence of two other bodies of water ( Rio de Loures and Ribeira de Odivelas ) in the municipality of Frielas .

The Trancão itself is a tributary of the Tagus. Opposite Samouco ( Alcochete district ) it flows into the mouth of the Tejo.

history

The Trancão was formerly called the Rio de Sacavém , which is due to the fact that Sacavém was the most important place in the area and spread out on both sides of the river (São João da Talha was only separated from Sacavém in 1387 ).

The first military conflict between D. Afonso Henriques and the Moors took place on the banks of the Sacavém in 1147 , long before the capture of Lisbon - the Battle of the Rio Sacavém .

Until the 19th century , the river was an important transport route in the rural suburbs of Lisbon . The agricultural products with which Lisbon was supplied were unloaded at the Rio Trancão. The building materials for the construction of the Convento de Mafra under King D. João V also came via the Trancão.

Since the earthquake of 1755 , which devastated Lisbon, the river slowly began to silt up and become impassable.

A bridge over the Trancão, over which the Roman road led from Lisbon to Braga , has existed since Roman times . Today, in addition to the bridge between Sacavém and Bobadela (EN10), there is also a large viaduct over which the Auto-Estrada do Norte ( north motorway , A1) leads.

Ecological situation

Since the middle of the 20th century, the Rio Trancão has been polluted by industrial sewage from factories on both sides of its bank, turning the river into dead and malodorous water. In preparation for the prestigious World Exhibition Expo 98 project , a major clean-up was then tackled, which also included the construction of a sewage treatment plant in Frielas . Today the river has been largely revived and is considered a prime example of cleaning up flowing waters within Portugal.