The Douro estuary (Portugal): a mesotidal salt wedge

• Type: Article in International Scientific Journal
• Date: 2000

Authors

Vieira, MEC (Author) Other; Adriano Bordalo (Author) ICBAS

Journal

Title: Oceanologica Acta

Vol. 23

Pages: 585-594

ISSN: 0399-1784

Publisher: EDP Sciences

Indexing

ISI Web of Knowledge - 52 Citations

Scopus - 53 Citations

Other information

Authenticus ID: P-000-Z5H

DOI: 10.1016/s0399-1784(00)01107-5

Abstract (EN): The Douro River drains a large part of the Iberian Peninsula before it flows into the Atlantic Ocean in northern Portugal. Although heavily dammed throughout its course, the Douro forms a mesotidal estuary in the last 22 km. Na data had ever been collected in this estuary prior to 1994. An analysis of salinity data measured once a month in 1994 and current data obtained in the fall of 1994 revealed a salt wedge estuary highly dependent on river discharge: strong vertical salinity stratification under conditions of low runoff, whereas during high river flows the whole estuary became a river. The tide in the fall of 1994 was very close to a standing wave throughout the estuary; the tidal range, as high as 2.8 m at spring tides, was not powerful enough to destroy the vertical stratification. Tidal straining prevented mixing within the salt wedge during ebb; however, the column became vertically mixed at the end of hood. The salt wedge became arrested at three favored positions determined by the bathymetry. The salt intrusion, more sensitive to freshwater inflow than to tidal action, penetrated as far as 2/3 of the estuary's length. Residence times were estimated with a box model and were dependent on river discharge; they varied from 8 hours with early spring (March) inflows to 16 days under summer runoff conditions. (C) 2000 Ifremer/CNRS/IRn/Editions scientifiques et medicales Elsevier SAS.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 10