Human activities have reshaped coastal environments along the rocky coast of the Atacama Desert, particularly through the extreme sediment input resulting from mining operations. A recent study focused on the Chañaral coast highlights the dramatic effects of ~400 million tons of copper mine tailings dumped between 1938 and 1990, which radically transformed local beach landscapes.
Researchers investigated how this vast sediment supply influenced the dynamics of pocket beaches, resulting in significant alterations to the shoreline. The study revealed two distinct growth patterns of beaches based on sediment input locations, characterized as radial-to-rectilinear and lateral-to-bypassed accretion forms.
Before the dumping of tailings, the natural sediment supply rate to Chañaral was low due to the region’s hyperarid climate. The tailings discharge created what is described as an anomalous positive sediment budget, leading to notable beach growth rates among the highest recorded globally. The study, conducted collaboratively by researchers from various institutions, employed aerial photographs and satellite imagery to analyze historical shoreline changes over nearly a century.
According to the findings, the periods of tailings discharge coincided precisely with the growth of the existing Playa Grande beach and the formation of two artificial beaches, El Refugio and Los Amarillos. The research characterized the shoreline advance rates at up to 22 meters per year, dramatically contrasting with retreat rates following the cessation of tailings dumping.
Significant beach erosion emerged after the tailings discharge concluded, indicating instability and disequilibrium within these mined areas. With the cessation of sediment supply, Playa Grande and El Refugio beaches experienced mean erosion rates of -1.5 and -3.3 meters per year, respectively.
This study emphasizes the necessity of considering human-induced changes alongside natural processes when evaluating coastal dynamics. The results provide urgent insights for coastal management decisions, particularly for regions susceptible to degradation due to anthropogenic influences.
Overall, the research not only highlights the expansive impact of mining activities on coastal sedimentation but also sets the stage for future investigations aiming to model and understand the complex interactions between human actions and natural coastal processes.