Amazon Delta in the context of "River deltas"

A river delta is a landform, archetypically triangular, created by the deposition of the sediments that are carried by the waters of a river, where the river merges with a body of slow-moving water or with a body of stagnant water. The creation of a river delta occurs at the river mouth, where the river merges into an ocean, a sea, or an estuary, into a lake, a reservoir, or (more rarely) into another river that cannot carry away the sediment supplied by the feeding river. Etymologically, the term river delta derives from the triangular shape (Δ) of the uppercase Greek letter delta. In hydrology, the dimensions of a river delta are determined by the balance between the watershed processes that supply sediment and the watershed processes that redistribute, sequester, and export the supplied sediment into the receiving basin.

River deltas are important in human civilization, as they are major agricultural production centers and population centers. They can provide coastline defence and can impact drinking water supply. They are also ecologically important, with different species' assemblages depending on their landscape position. On geologic timescales, they are also important carbon sinks.

The Tocantins River (Portuguese: Rio Tocantins Portuguese pronunciation: [ˈʁi.u tokɐ̃ˈtʃĩs, tu-], Parkatêjê: Pyti [pɨˈti]) is a river in Brazil, the central fluvial artery of the country. In the Tupi language, its name means "toucan's beak" (Tukã for "toucan" and Ti for "beak"). It runs from south to north for about 2,450 km (1,520 mi). While sometimes included in definitions of the Amazon basin, the Tocantins is not a branch of the Amazon River, since its waters flow into the Atlantic Ocean via an eastern channel of the Amazon Delta, alongside those of the Amazon proper. It flows through four Brazilian states (Goiás, Tocantins, Maranhão, and Pará) and gives its name to one of Brazil's newest states, formed in 1988 from what was until then the northern portion of Goiás.

The Tocantins is one of the largest clearwater rivers in South America.

Belém (Portuguese: [beˈlẽj]; Portuguese for Bethlehem; initially called Nossa Senhora de Belém do Grão-Pará, in English Our Lady of Bethlehem of Great Pará), often called Belém of Pará, is the capital and largest city of the state of Pará in the north of Brazil. It is the gateway to the Amazon River with a busy port, airport, and bus/coach station. Belém lies approximately 100 km (62.1 miles) upriver from the Atlantic Ocean, on the Pará River, which is part of the greater Amazon River system, separated from the larger part of the Amazon delta by Ilha de Marajó (Marajo Island). With an estimated population of 1,398,531 people — or 2,491,052, considering its metropolitan area — it is the 12th most populous city in Brazil, as well as the 16th by economic relevance. It is the second largest in the North Region, second only to Manaus, in the state of Amazonas.

Founded in 1616 by the Kingdom of Portugal, Belém was the first European colony on the Amazon but did not become part of Brazil until 1775. The newer part of the city has modern buildings and skyscrapers. The colonial portion retains the charm of tree-filled squares, churches and traditional blue tiles. The city has a rich history and architecture from colonial times. Recently, it witnessed a skyscraper boom.

Macapá (Brazilian Portuguese pronunciation: [makaˈpa] ) is a city in Brazil with a population of 512,902 (2020 estimate), and is the capital of Amapá state in the country's North Region, located on the northern channel of the Amazon Delta near its mouth on the Atlantic Ocean. The city is on a small plateau on the Amazon in the southeast of the state of Amapá. The only access by road from outside the province is from the overseas French department of French Guiana, although there are regular ferries to Belém, Brazil. Macapá is linked by road with some other cities in Amapá. The equator runs through the middle of the city, leading residents to refer to Macapá as "The capital of the middle of the world." It covers 6,407.12 square kilometres (2,473.80 sq mi) and is located northwest of the large inland island of Marajó and south of the border with French Guiana.

Vieira Grande Bay (Portuguese: Baía do Vieira Grande) is a bay off the Brazilian coast located in the state of Pará. The bay forms one of the main river channels in the Amazon Delta.

The bay is fed in the South by the Jacaré Grande River and by a complex system of numerous river channels that are called furos in Portuguese. These channels form a link between the Amazon and the Vieira Grande Bay. The influence of the Amazon waters can be shown for example through the occurrence of the phytoplankton Thalassionema nitzschioides in the bay.