Changes in wave climate and its impact on the coastal erosion in Samborombón Bay, Río de la Plata estuary, Argentina

BACINO, GUIDO L.; DRAGANI, WALTER C.; CODIGNOTTO, JORGE O.

ESTUARINE COASTAL AND SHELF SCIENCE

ACADEMIC PRESS LTD-ELSEVIER SCIENCE LTD

Año: 2019 vol. 219 p. 71 - 80

0272-7714

Salt marsh boundary in Samborombón Bay, Río de la Plata Estuary, is rapidly eroding. A 90 cm vertical scarp characterizes the shoreline and exposes the present-day rootmat and the underlying mud unit. Preliminary investigation supports that higher waves are becoming more frequent in the coastal area of the bay and, as a consequence, the edge scarp would be more frequently exposed to higher levels of wave energy, driving to larger erosion. The aim of this paper is to build a realistic model of the wave climate, to investigate if the coastal wave parameters are actually changing, and to analyze if the wave climate and its possible change are in agreement with an acceleration in the erosive processes reported in the bay. Numerical simulations carried out using SWAN model were validated using in-situ and satellite wave parameters. It was shown that highest waves (propagating from the E and NE) are becoming more frequent in the coastal area of the bay. As a consequence, the edge scarp would be more frequently exposed to higher levels of wave energy, driving to larger erosion. It was also concluded that the incident wave energy flux is one order of magnitude greater than the alongshore energy flux and it is quite homogeneous along the coast of the bay. A linear relationship between the measured marsh edge retreat and the incident wave energy flux was found. Positive correlation was obtained between two climatic indices (ENSO and SAM) and the frequencies of occurrence of waves coming from NE.