Recent Coastal Geomorphological Evolution in the Negro River's Mouth (41°S), Argentinean Patagonia

VERGARA DAL PONT, IVÁN P.; CASELLI, ALBERTO T.; MOREIRAS, STELLA M.; LAURO, CAROLINA

JOURNAL OF COASTAL RESEARCH

COASTAL EDUCATION & RESEARCH FOUNDATION

Año: 2017 vol. 336 p. 1367 - 1375

0749-0208

This paper analyzes the geomorphologic evolution of the Negro river?s mouth to understand dynamic conditions of the Atlantic coast at 34º S. Historical river flow and morphometry of these beaches were studied. Our first outcomes conclude a dichotomous coast condition at this latitude. Cliff developed in the SW area present marked erosion due to a coastline?s average recoil of 0.69 m/year during 1959-2011. Instead, extensive beaches in the NE area resulted more stable with a prominent accretion. In this sector, a relatively fast coastal accretion was corroborated by the 170 m advances of the berms in between 1986 and 2014. Lateral extension of these beaches grew 760 m in with during the same period. Since 1936, a new particular process was observed at the Negro river?s mouth. Displacement of intertidal banks and accretion towards, and along, the coastline provoked the closure of fluvial channels and tidal currents. That increased separation with the continent. In our opinion, the dynamic of the Negro river´s mouth was forced by the reduction of river´s discharge during the 20th century increasing the littoral current influence.