Hidrologia de um estuário verticalmente bem misturado da costa nordeste semi-árida brasileira

Abstract

This study focuses on the ebb and flood water inputs for dry and rainy seasons to the Jaguaribe River estuary (Brazil). The Jaguaribe Basin covers 72,043 km2 , representing almost half of the Ceará State’s territory in Northeastern Brazil. It extends along 633 km contributing to the Western Equatorial Atlantic Ocean. The observed tidal regime is of the meso-tidal semi-diurnal type; Methods: In 2004, the average velocities of flood and ebb tides were calculated using a spherical buoy, a limnimetric ruler and a deterministic model. In 2005, a comparative study between the measures performed with the buoy and an Acoustic Doppler Current Profiler (ADCP) was also carried on; Results: The average velocities of flood and ebb tides, using the spherical buoy, the limnimetric ruler and the deterministic model, varied from 0.11 to 0.24 m.s–1 (flood) and from 0.11 to 0.28 m.s-1 (ebb). In 2005, the measures done with the buoy and the Acoustic Doppler Current Profiler (ADCP) presented differences between 50 and 80%. However, in 2005, the water fluxes calculated from average velocities measurements (101.1 m3 .s-1 using the spherical buoy and the limnimetric ruler; and 115.3 m3 .s-1using the ADCP) showed a smaller error; Conclusions: The comparability of the two techniques to calculating average water fluxes to 12 hours sampling campaigns pointed the similarity between these data. During these evaluated periods the tidal prism presents seasonal variation between 12.6 and –73.1 m3.s-1 showing a smaller tidal prism during the dry season and with an increasing tendency in the rainy period. The Jaguaribe estuary is an importer system of marine waters explaining the dominance of marine biogeochemical processes in the estuary