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| Magdalena River delta and Santa Marta lagoon complex |
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Caribbean Coast: Magdalena River delta and Santa Marta lagoon complex
West of the Santa Marta massif, between Santa Marta and Barranquilla (Fig. 2), the coastal zone is characterized by the extensive Ciénaga de Santa Marta shallow (< 4 m) lagoon and the adjacent Quaternary deposits of the Magdalena River delta. The Magdalena River is the most important river of Colombia, draining a basin of 250,000 km2 on the Andes Cordillera (Restrepo and Kjerfve 2000).
The Holocene Magdalena River delta and adjacent Santa Marta lagoon occupy a low area bounded by the Sierra Nevada de Santa Marta massif and by the coastal relief of the San Jacinto Belt, west of the present course of the Magdalena River (Fig. 8). This sector is the most extensive depositional area on the Caribbean coast of Colombia. The apex of the delta is about 45 km inland from the river mouth, at the jetties of Bocas de Ceniza (Raasveldt and Tomic 1958, Robertson 1998).
Figure 8. Space photograph of the Magdalena delta and Santa Marta lagoon. The Salamanca bar has an approximate length of 65 km between Tasajera and Bocas de Ceniza; jetty length is 9 km, coinciding with the delta protuberance east of the river mouth. SNM: Sierra Nevada de Santa Marta; MRD is the active Magdalena River Delta; B marks the city of Barranquilla. Image reference ISS002-732-73. Reproduced by permission of Earth Sciences and Image Analysis Laboratory, NASA Johnson Space Center. |
The Santa Marta lagoon and mangrove system has only one open connection with the sea (Tasajeras mouth) and is confined by the Salamanca bar, a sandy barrier about 65 km long that forms the present coastline of the Magdalena delta. The Salamanca bar has a maximum height of about 2 m above present sea level and has been historically subjected to intense erosion, currently reflected by the generalized beach retreat along most of its length and by the frequent overwash events along the eastern Magdalena delta (Fig. 9).
Figure 9. Typical transgressive beach along the Salamanca bar coastline of the Magdalena River delta. Beach retreat is destroying the mangrove vegetation and the dunes of the bar, and washover is filling the lagoon of the delta fringe. Photo by I. Correa. |
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