Beach-morphodynamic changes conditioned by the Holocene sea-level fluctuation: Mesotidal beaches of Northern Patagonia.

FEDERICO IGNACIO ISLA; BERTOLA G R; FERNANDEZ, JUAN MANUEL; BEDMAR JOSE; TOFFANI MAURICIO; GARZO PEDRO

ISSN: 0567-7513 - e-ISSN: 1852-6217 - Acta Geologica Lilloana

Fundacion Lillo

Lugar: S M del Tucuman; Año: 2023 vol. 34 p. 111 - 128

0567-7513

Beach morphodynamics are stated as depending on wave climate, tidal range and grain size. Sediment availability is a conditioning factor biased to inheritance factors. Seven natural beaches from Northern Patagonia: 4 from Southern Buenos Aires and 3 from Eastern Rio Negro Province were surveyed during several years. La Chiquita Beach is characterised by an abundance of fine sand supplied by the Colorado River delta. Pocitos Beach is rather stable although it is changing due to colonisation by the invasive reef-building oyster Crassostrea virginica. Faro Segunda Barranca is an open-ocean beach, very affected by extratropical storms coming from the SE. The beach of Villa Siete de Marzo has a very active dynamics affected by the embankments of the Negro River outlet, and episodic storms. The beach of Balneario El Cóndor is very wide with an intense strong longshore drift from west to east. The beach in front of the San Matías Lighthouse (Villarino Peninsula) is controlled by an abrasion platform close to the low-tide limit. Las Grutas beach is also controlled by an abrasion platform but the sand abundance is related to the ebb-tidal delta of the San Antonio Gulf. Open-ocean beaches in Buenos Aires province are very affected by a drift towards the north delivered by South Atlantic waves. On the other hand, Rio Negro beaches are affected by the strong westerly winds blowing alongshore.