SORTING OUT THE CULPRITS OF COASTAL EROSION IN DELTAIC AREAS

Coastal erosion is currently affecting numerous coastlines worldwide and endangering coastal communities and valuable natural ecosystems such as wetlands and beaches. Quantifying coastline changes through time has traditionally been done using aerial photographs, satellite images, or Lidar data. In contrast to the well established methods for tracking coastline changes, pointing out the specific causes of coastal erosion for a particular study site remains elusive. It has been established that global climate change and associated rising sea-levels play a key role in current coastal changes at a global scale. However, to properly face and mitigate coastal changes at a local level, it is necessary to recognize and characterize the specific processes affecting a coastline.

Historical records of tidal gauges help establish sea-level trends for a particular region that result from global (eustatic) and local (isostatic) sea-level changes. To explain sea-level changes, the downward movement of the terrain (i.e., subsidence) is a process that is widely mentioned but rarely quantified when attempting to explain erosive processes in coastal deltas. By correlating coastal changes to subsidence rates for a deltaic area, this work looks at establishing the role that subsidence has played in the coastal dynamics of a highly erosive deltaic area in Isla Salamanca National Park in the Colombian Caribbean. Satellite images and bimonthly radar data have been used to assess past coastal changes and subsidence levels, respectively. The results of this work will provide insights about how subsidence rates correlate to coastlines changes over time, contributing to establish a methodology that explains the response of coastlines to subsidence processes.