RATES OF COASTAL EROSION AND AGGRADATION FOR THE PANAMA VIEJO UNESCO WORLD HERITAGE SITE

The purpose of this study was to measure historical (~1500 AD - present) rates of coastal erosion and deposition and estimate current trajectories of coastal erosion for the Panama Viejo World Heritage UNESCO site located on the Gulf of Panama in the south-central region of the Republic of Panama. Here we present our results from using the United States Geological Survey’s Digital Shoreline Analysis System (DSAS), integrated with a Geographic Information System (ESRI ArcGIS) to gather shoreline migration data from historical maps and aerial photos from the archives of the Universidad de Panamá and the Patronato Panamá Viejo. We find that, on average, the coastal area immediately adjacent to Panama Viejo has eroded at rates of ~0.3 m per year for the past ~500 years, with rates of erosion as high as 5 m per year in the recent past. These rates of erosion suggest that the Panama Viejo shoreline was, on average, ~150 m or more seaward of its current location ~500 years ago, shortly after the city was first established. Recent rates of erosion and deposition along the Panama Viejo coastline range between ~3 meters per year of localized coastal erosion and 5 meters per year of localized coastal aggradation. We find that these patterns in coastal erosion and aggradation correlate with anthropogenic ally-driven activity in the area. For example, many observable short-term pulses of erosion and aggradation correlate with episodes of local road construction, while average long-term rates of erosion and aggradation seem to correlate with the presence or absence of mangrove forests in the coastal area near Panama Viejo. Historical records and near shore excavations suggest that much of the pre-colonial (pre 1500) Panama Viejo coastline was covered in mangrove forests. We suggest that reemergence of mangrove forests along the shoreline in areas adjacent to the site is the key to the long term preservation of the Panama Viejo World Heritage site.