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Coastal and Marine Geology Program > St. Petersburg Coastal and Marine Science Center > Coasts of Colombia

Coasts of Colombia

Coasts of Colombia
Pacific Coast:
Introduction
Serranía del Baudó (Baudó Range)
Cabo Corrientes-
Togoromá
San Juan River Delta
Málaga Bay - Buenaventura Bay
Buenaventura Bay - Guapi
Patía River Delta
Tumaco Bay
Mira River Delta
Gorgona Island
Malpelo Island
References
Caribbean Coast:
Introduction
Guajira Peninsula Coast
Sierra Nevada de Santa Marta Coast
Magdalena River delta and Santa Marta lagoon complex
Barranquilla - Cartagena coast
Southern Caribbean coast
Gulf of Urabá
References
Project Contact:
Robert Morton

Pacific Coast: Patía River delta

The Patía River delta (Fig. 30), which is the most important Plio-Quaternary depocenter of the Pacific Coast of Colombia, drains about 23,000 km2 of the Central and Western Cordilleras of the Colombian Andes. The delta consists of the northern ancient delta plain (Fig. 30) and the western, more recent delta plain. This zonation results from the progressive NE to SW delta migration. Both delta zones have been influenced by Quaternary and recent tectonic movement (Van Es 1975).

Geomorphic classification of the Patía River delta.
Figure 30. Geomorphic classification of the Patía River delta. Modified from Correa (1996).

The Patía delta coastline is approximately 120 km long and extends from the Guapi Bay to Punta Cascajal, at the northwestern extreme of Tumaco Bay (Fig. 30). The northern Patía delta fringe is a subsiding, tide-dominated area characterized by frontal, erosional lobes of sandy-muddy tidal flats backed by mangrove swamps and an ancient complex of beach ridges (Gomez 1986). Numerous "funnel-shaped" estuaries and tidal channels penetrate more than 15 km to the interior of the northern Patía delta plain (Fig. 31), where mangrove and transitional swamps are rapidly eroding (Fig. 32). The erosion produces a pattern of numerous isolated small islands.

Littoral erosion along the northwestern area of the Patía River delta plain.
Figure 31. Littoral erosion along the northwestern area of the Patía River delta plain. Radar image showing disintegration of mangrove swamps and internal beach-ridge systems. Semi-circular areas (FWS) represent progressive salinization of fresh-water swamp. Reproduced by permission of Instituto Geográfico Agustín Codazzi (IGAC) and INTERA Information Technologies (STAR-1 radar).

Mangrove swamp erosion along the Sanquianga River estuary.
Figure 32. Mangrove swamp erosion along the Sanquianga River estuary. Photo by I. Correa.

The western and southern shores of the Patía delta (Fig. 33) consist of external sets of barrier islands and mangrove and transitional swamps backed by intricate sets of point bars and sandy fluvial deposits of numerous abandoned courses of the Patía River. Barrier islands of this sector have the best dune development (2 m high) of the barrier islands of the Pacific Coast of Colombia. Nevertheless, the barriers exhibit transgressive characteristics with abundant breaches and island segments (Martínez et al. 1995).

Western flank of the recent Patía River delta.
Figure 33. Western flank of the recent Patía River delta. Radar image showing San Juan de la Costa barrier island, flooded at its central part, and numerous abandoned courses of the Patía River. The island was breached by El Niño related overwash events of 1997-1998. Reproduced by permission of Instituto Geográfico Agustín Codazzi (IGAC) and INTERA Information Technologies (STAR-1 radar).

The entire Patía delta has been affected in historical times by co-seismic subsidence, best recorded in the December 12, 1979 earthquake that affected the Southern Pacific Coast from the Mira River delta to Guapi Bay. This event in particular caused a regional subsidence maximum of about 1.6 m along the shores of the San Juan barrier island, and its associated tsunami killed about 155 people at the San Juan de la Costa village, located on the central part of this island (Herd et al. 1981).

In 1969, the Patía River's southern branch to the Sanquianga River (northern delta plain) was artificially diverted. Since then, the southern shores of the Patía delta and adjacent northern Tumaco Bay have been retreating about 0.5 m/year (Fig. 34).

Erosion of the southern beaches of the Patía River delta.
Figure 34. Erosion of the southern beaches of the Patía River delta. Photo by I. Correa.

Coastal and Marine Geology Program > St. Petersburg Coastal and Marine Science Center > Coasts of Colombia

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