Influence of physical drivers on the variability of shoreline position in western South America

Coastal zones play an important role for coastal communities, infrastucture and ecosystems.
They are considered as complex systems that are constantly affected by the human activities and
the climate. Due to the configuration of the coastline, some drivers have a greater impact on the
coastline at different times of the year. Here we present a regional evaluation of the shoreline
changes over 27 years (1999-2019) based on satellite observations and reanalysis data. We study
the main hydrodynamic drivers of the coastal variability: the sea level, ocean waves and wind stress
(alongshore) on intraseasonal timescales in the western of South America. We analyse the monthly
changes in the shoreline as a linear function of the physical drivers, which are modulated by: the
Equatorial Oceanic Kelvin Wave and the coastal trapped wave that have the major variability in
the austral winter at the equator, the Coastal Jet that characterize the wind bursts in the Pisco and
Central Chile region in the austral fall and the extratropical storm activity that module the waves.
We found that theses drivers contribute to the most of the variability in the northern region (from
Ecuador to the central Peru region 15°S) during June-August, and to the southern region (from
central Peru to the central Chile 35°S) during December-February. Our results provide insight
into the effects of physical forcing over the coastline on intraseasonal timescales, which can result
from atmospheric and oceanic perturbations from tropical-extratropical teleconnexions, that can
be considered in the context of community resilience.