Examinando por Autor "Contreras-López, Manuel"

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  • Miniatura
    Ítem
    Coastal erosion in sandy beaches along a tectonically active coast: The Chile study case
    (Sage, 2022) Martínez, Carolina; Winckler Grez, Patricio; Agredano Martín, Roberto; Esparza Acuña, César; Torres, Iván; Contreras-López, Manuel
    Coastal erosion in 45 sandy beaches covering nearly 2000 km along the tectonically active Chilean coast is assessed during the last four decades. The historical analysis is based on the assessment of decadal changes of the shoreline position extracted from topographic surveys, aerial photographs, satellite images and survey maps using the DSAS software. Results show that 80% of the sites presented erosion rates (>−0.2 m/y), 7% beaches accreted (>0.2 m/y) while 13% remained stable. Eroded beaches include headland bay beaches, embayed and pocket beaches. A discussion on the possible causes explaining these results is conducted. While changes in offshore wave climate are spatially smooth within the region, relative mean sea level changes are highly variable and modulated by tectonic activity; the reduction of the sediment supply explains erosion rates in few cases.
  • Miniatura
    Ítem
    Evidence of climate-driven changes on atmospheric, hydrological, and oceanographic variables along the Chilean coastal zone
    (Springer, 2020) Winckler Grez, Patricio; Aguirre, Catalina; Farías, Laura; Contreras-López, Manuel; Masotti, Ítalo
    The Chilean coastal zone (CCZ) is subjected to a complex spectrum of anthropogenic, geophysical, biogeochemical, and climate-driven perturbations. Potentially affected variables including atmospheric sea level pressure (Pa), alongshore wind, sea surface temperature (SST), chlorophyll-a, rainfall, river discharge, relative mean sea level (RMSL), and wave climate are studied using in situ and satellite records, hindcasts, and reanalysis datasets. Linear temporal trends and correlations of anomalies are estimated between 18°S and 55°S along the CCZ. The comparison of some of the variables is achieved by means of a strict homogenization procedure on a monthly basis for 35 years. Our findings show that the poleward drift and strengthening of the Southeast Pacific Subtropical Anticyclone (SPSA) partially explains the increase in Pa and reduction in rainfall and river discharge. The enhancement of alongshore winds, also attributable to changes in the SPSA, increases coastal upwelling, which in turn could reduce SST and increase chlorophyll-a. Despite differential latitudinal responses, increasing wave heights and a southward rotation are evidenced. RMSL does not show significant variation as it is presumably affected by seafloor changes during the seismic cycle. Though some correlations are evidenced, the influence of climate variability at decadal scale (PDO, SAM) may be affecting the detected trends due to the short length of available data. Impacts on coastal communities, infrastructure, and ecosystems are discussed, aiming to highlight that coastal vulnerabilities and risk management should be based on the cumulative impacts of these variables.