Projections of Beach Erosion and Associated Costs in Chile

Abstract

Economic costs associated to coastal erosion are projected in 45 sandy beaches in Chilean coasts. We compare mid-century (2026–2045) and end-of-century projections (2081–2100) of wave climate and sea-level rise (SLR) with a historical period (1985–2004) using several General Circulation Models for the RCP 8.5 scenario. Offshore wave data are then downscaled to each site, where shoreline retreat is assessed with Bruun rule for various berm heights and sediment diameters. Results indicate that mid-century retreat would be moderate (>13 m) while larger end-of-century projections (>53 m) are explained by SLR (0.58 ± 0.25 m). A small counterclockwise rotation of long beaches is also expected. To assess the costs of shoreline retreat, we use the benefit transfer methodology by using adjusted values from a previous study to the sites of interest. Results show that, by mid-century, beach width reduction would be between 2.0% and 68.2%, implying a total annual loss of USD 5.6 [5.1–6.1] million. For end-the-century projections, beach width reduction is more significant (8.4–100%), involving a total annual loss of USD 10.5 [8.1–11.8] million. Additionally, by the end-of-century, 13–25 beaches could disappear. These costs should be reduced with coastal management practices which are nevertheless inexistent in the country.

A Systematic Review of Oceanic-Atmospheric Variations and Coastal Erosion in Continental Latin America: Historical Trends, Future Projections, and Management Challenges

“…For instance, the counterclockwise rotation of wave patterns is projected in the sandy beaches of Chile, although it is less intense than waves in the deep sea due to wave refraction near the coast. This could result in straight beaches experiencing erosion at their southern ends, and accretion at the northern ends [116][117][118].…”

“…Considering that Chile's coasts are vulnerable to the effects of ENSO, variations in mean sea level can fluctuate by up to ±30 cm [45,116]. According to a recent study [118], an increase in mean sea level of 0.14 m is projected for 2050, and one of 0.58 m for 2100, under the high emissions scenario (RCP 8.5) in the Valparaíso area.…”

“…Understanding the intricate interplay between extreme events, sea-level rise, and climate patterns is crucial for grasping their impact on coastal erosion in Latin America. Much of the sandy coastline in this region accommodates urban infrastructure, including residences and hotels, located within 30 m from the shoreline [88,102,118]. During extreme events like cyclonic surges or high-intensity waves, there is an elevated risk of partial or total damage to these properties, a risk that may escalate in future scenarios.…”

“…In Chile, a retreat of 2.00 m to 13.00 m is projected by 2050, and one of 10.00 m to 53.00 m by 2100 under the RCP8.5 scenario, exacerbating coastal infrastructure exposure to extreme events. The reduction in beach width would also impact tourism, with economic losses estimated at over USD 5 million per year by 2050, and over USD 10 million per year by 2100, with some beaches possibly disappearing by the end of the century [118].…”

Understanding the impact of hydrodynamics on coastal erosion in Latin America: a systematic review

“…Additionally, changes in coastal dynamics also affect coastal biodiversity, recreational values of beaches, and cultural heritage sites. Therefore, multidisciplinary research is needed to develop conservation strategies for these natural ecosystems, as well as regulations and strategies guiding future urban development in erosion-prone coastal areas (Silva-Casarin et al, 2012;Merlotto et al, 2014;Barragán-Muñoz, 2020;Vellanoweth et al, 2020;Winckler et al, 2023).…”