The Rio Acaraú is a significant river system flowing through the state of Ceará in northeastern Brazil, stretching approximately 315 kilometers from its headwaters in the mountainous terrain near Monsenhor Tabosa — at elevations around 800 meters — southward to its mouth at the Atlantic Ocean near the town of Acaraú. The river drains a basin of roughly 14,427 square kilometers, making it one of the more substantial watersheds in Ceará. The river follows a general south-to-north orientation and is classified as a fifth-order stream, reflecting its considerable size and the number of tributaries that feed into it. The basin encompasses a range of landscapes typical of the Caatinga biome — the semi-arid scrubland of northeastern Brazil — and the river's flow regime is strongly influenced by seasonal rainfall patterns, with flood pulses occurring during the summer-autumn rainy season. Numerous reservoirs and dams have been constructed throughout the basin over the decades, particularly during the 1940s through 1960s, fundamentally shaping the hydrology and fish communities of the river system today.