Riacho vs. córrego vs. ribeiro vs. ribeira
While riacho, córrego, ribeiro, and ribeira all refer to watercourses smaller than a river, their usage depends heavily on regional differences between Brazil and Portugal, as well as the specific size and setting of the stream.
Riacho
B1This is a diminutive form of rio (river). It is the most common term in Brazil for a natural, shallow creek found in rural areas or nature. It usually implies clean water and a setting where one might swim or fish.
As crianças passaram a tarde brincando no riacho perto da fazenda.
(The children spent the afternoon playing in the creek near the farm.)
A água deste riacho é cristalina e muito fria.
(The water in this brook is crystal clear and very cold.)
Durante a seca, o pequeno riacho desaparece completamente.
(During the drought, the small stream disappears completely.)
Nós cruzamos o riacho pulando de pedra em pedra.
(We crossed the creek by jumping from stone to stone.)
Córrego
B2Derived from the verb to run/flow, this term describes a narrow channel of water. In Brazil, it often has a technical or topographical usage. In urban contexts, córrego is frequently used to describe small streams that traverse cities, sometimes implying they are channeled or polluted.
A prefeitura decidiu canalizar o córrego para evitar enchentes.
(The city hall decided to channel the stream to prevent floods.)
Existe um pequeno córrego que divide as duas propriedades.
(There is a small brook that divides the two properties.)
Infelizmente, jogaram lixo no córrego que passa atrás da fábrica.
(Unfortunately, they threw trash in the stream that runs behind the factory.)
O mapa mostra um córrego que nasce na colina.
(The map shows a creek that originates on the hill.)
Ribeiro
C1Used primarily in European Portuguese (Portugal) and literature. It refers to a very small, idylic brook, smaller than a ribeira. It evokes a poetic image of a gentle, trickling watercourse in the countryside.
O poeta sentou-se à beira do ribeiro para escrever.
(The poet sat by the brook to write.)
Apenas um pequeno ribeiro corria pelo vale silencioso.
(Only a small stream ran through the silent valley.)
Os caminhantes encheram os cantis na água fresca do ribeiro.
(The hikers filled their canteens in the fresh water of the brook.)
O som do ribeiro ajudava a adormecer.
(The sound of the stream helped one fall asleep.)
Ribeira
B2Very common in Portugal, referring to a watercourse that is larger than a ribeiro but smaller than a full river. Ribeira can also refer to the riverbank or waterfront area itself (e.g., Ribeira do Porto). In Brazil, it is largely archaic for streams but appears in place names.
A chuva forte fez a ribeira transbordar e inundar a estrada.
(The heavy rain caused the stream to overflow and flood the road.)
Eles construíram uma ponte de madeira sobre a ribeira.
(They built a wooden bridge over the stream.)
Esta ribeira deságua no rio principal a quilômetros daqui.
(This large creek flows into the main river kilometers from here.)
Antigamente, as mulheres lavavam roupa na ribeira.
(In the past, women washed clothes in the stream.)
Summary
To summarize, use riacho for a standard rural creek in Brazil. Use córrego for narrow streams, often in Brazilian geography or city planning. Use ribeiro for very small brooks in Portugal, and ribeira for larger streams or riverbanks in Portugal.