Abstract

MANCERA FLORES, Andrea et al. Morphodynamics of the Northern Coasts of the Veracruz State, Mexico: Trends over the Past Four Decades (1973-2017). Invest. Geog [online]. 2020, n.103, e60155.  Epub Mar 09, 2021. ISSN 2448-7279.  https://doi.org/10.14350/rig.60155.

The main objective of this paper is to calculate and evaluate the behavior of coastal morphodynamics in the northern coast of the state of Veracruz over the past 45 years (1973-2017) from regional and local perspectives. This study included three sites suitable for establishing engineering prototypes for the use of wave power and its conversion into electricity micro-generation in the coastal towns Barra de Cazones, Palma Sola, and Villa Rica. To this end, we used geospatial data of aerial photographs, ortho- photos and satellite images for different years (1973, 1986, 1995, 2000, 2011, and 2017) to identify and demarcate the shoreline based on Boak and Turner (2005). Subsequently, this attribute was classified according to its prevailing process (progradation or regression) in the DSAS module (USGS, 2012) to determine the shoreline change rates. Besides, a baseline was set to determine the potential future impacts of installing the engineering prototypes. According to the availability of inputs, the northern zone was approached regionally for the period 2000-2017, while Barra de Ca- zones and Palma Sola covered the years 1995-2017, and Villa Rica encompassed the years 1973-2017. The results in terms of the net shoreline movement (NSM) show an overall regional trend toward the prevalence of progradation in the northern coast. Progradation values reach up to +27 m near river mouths, dune fields, and anthropized areas, with figures higher than +90 m in some localities. Coastal regression shows values as high as -97 m and -27 m in fluvial- marine and wind-marine environments, as well as in highly anthropized areas. Barra de Cazones shows three distinctive sectors. The first shows a net shoreline regression of -16 m at Playa Chaparrales. The second sector, more widespread, comprises approximately 60% of the local coast, with pro- gradation values of up to +26 m. Finally, the third sector, in its northern part around the fluvial-marine bar near the Cazones river mouth, shows a regressive process reaching values between -16 and -27 m. Palma Sola displays an overall trend towards shoreline progradation, reaching its peak value in Palma Sola beach, with +51.59 m over 22 years. The most significant regression is located in the La Loma cliffs, with -28.29 m. Unlike the figures found for the progradation zones, regressive processes correspond to abrasive coasts (La Loma and Miradores), except for the Barra Palma Sola mouth and, with less intensity, the adjacent Playa Andrea. Finally, in Villa Rica, the entire abrasive mound coastline maintains regressive process rates. The greatest regression was recorded in the front cliff of the Villa Rica mound, with -17.03 m. Maximum progradation values of +90.27 m occur to the south of the mound. The southern sector shows greater dynamism, with values from -12 m to +90 m, corresponding to the characteristics of a cumulative coastline. At a regional scale, the statistical result of the endpoint rate (EPR) shows that most data range from -1 to +2 m/ year, dominated by progradation, in the period 2000-2011 In the period 2011-2017, 50% of the data varied from -3 to +1 m/year. At specific sites, the structural-geological context, whether frontal lavic spills (Miradores-La Loma and the Villa Rica mound) or tectonic ascents of coastal blocks (Barra de Cazones), largely determines the morphogenetic development of the coastal relief and its most recent morphodynamics. Its variations according to the end point rate (EPR) indicate that progradation is the dominant process in Palma Sola and Villa Rica, whereas regression is prevalent in Barra de Cazones. In general, the northern coast of Veracruz shows a predominance of progradation processes. Isolated localities show prevalent regressive processes in response to the local physical-geographic conditions, which are in turn determined by the geological-geomorphological context and the presence of human settlements related to tourist- recreational activities.

Keywords : coastal morphodynamics; progradation and regression; net shoreline movement; end point rate.

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