pororoca
pororoca,
tidal bore: see AmazonAmazon,Port. Amazonas , world's second longest river, c.3,900 mi (6,280 km) long, formed by the junction in N Peru's Andes Mts. of two major headstreams, the Ucayali and the shorter Marañón.
..... Click the link for more information. , river, Brazil; borebore,
inrush of water that advances upstream with a wavelike front, caused by the progress of incoming tide from a wide-mouthed bay into its narrower portion. The tidal movement tends to be retarded by friction as it reaches the shallower water and meets the river current; it
..... Click the link for more information. .