Dynamics of coastline changes in Mexico

Abstract

The goal of our work was to locate and quantify changes that occurred in 66% of the Mexican coastline, based on four land cover maps generated by the Mexican Mangrove Monitoring System (SMMM) of the National Commission for the Knowledge and Use of Biodiversity (CONABIO) for the years 1970/81, 2005, 2010, and 2015. Our results showed overall dominance of erosion over accretion processes, beaches being the most affected coastal land cover. Emphasis was placed on identification and description of coastline sites in which land was either continuously lost (erosion) or gained (accretion) during the studied time periods. These sites were defined as continuous unidirectional dynamic sites and were compared with previous knowledge about the geodynamics of Mexican coasts. Continuous unidirectional dynamic sites were distributed throughout the study area and within all land cover types, but predominantly corresponded to areas covered by mangroves in the states of Campeche and Nayarit. Finally, we found an intensification of coastal erosion-accretion processes over time; coastline change rates having duplicated between the earliest (1970/81–2005) and the two more recent (2005–2010, and 2010–2015) analysed time periods, with erosion rates for each corresponding period of –3 m/yr, –7.5 m/yr, and –7.3 m/yr, and accretion rates of 2.8 m/yr, 7.3 m/yr, and 6.9 m/yr, respectively.