Assessing Coastal Erosion and Sediment Removal in the sand bar of the Isla Salamanca: Implications for the Barranquilla-Ciénaga Highway and coastal marine biodiversity – Colombia

Abstract The behavior of the shoreline is one of the most changing environments on the earth's surface, characterized by the effects of coastal progradation and erosion. In the Colombian Caribbean coast there are erosive tendencies causing negative coastal morphological changes due to a marked anthropic influence. The objective of the research was to analyze the evolutionary trend of the coastline and quantify the volume of sediments removed from the beach profile, correlating the risks associated with the loss of coastal marine biodiversity in Isla Salamanca National Park. The analysis of shoreline and volume variation will be carried out in GIS using Google Earth Pro satellite images (2004, 2010, 2013, 2015, 2019 y 2021) and photogrammetric orthomosaics taken with a drone (10/2020-07/2021). From the DSM analysis it was possible to quantify the volume of sediment removed in the two sectors. Erosional processes along the Isla Salamanca coastal barrier have an average annual rate of coastal transgression of -4.8 m·yr -1 , with an average retreat of -82.8 m from the shoreline. Especificamente, a análise de curto prazo mostrou que no km 29 as taxas erosivas, assim como o volume de sedimento remobilizado, são menores que nos dois setores do km 19. This heterogeneous behavior is probably associated with the lack of sediment supply east of the barrier and due to the presence of the seawall and the little slope of the coast, causing part of the sediment that reaches km 19 Sector 1 by the coastal drift to be lost to the surf zone. The protection of the highway by the breakwater at km 19 only works as a temporary protection of the highway and does not neutralize the erosive phenomenon. Erosive processes along the coastal barrier of Isla Salamanca are natural and irreversible phenomena that are directly affecting the ecosystems and marine-coastal biodiversity of Isla Salamanca National Park. However, anthropic interventions in the coastal environment can accelerate these erosive processes. An uncharacterized the landscape which, added to the natural erosive processes, produce a risk to this sensitive wetland environment. There are a variety of possible actions to reduce the effect of changes in the landscape of the Isla Salamanca Natural Park, with road relocation as a priority.