THE MANGROVE SWAMP OF THE PACIFIC 

 LITTORAL OF COLOMBIA 



Robert C. West 

 Louisiana State University 



Contract Nonr -454(00) 

 TaskNR 388-059 



A study has been made of the physical characteristics of the Pacific coast of Colombia 

 and of certain relationships between these characteristics and problems of travel and living 

 along the coast. Data for these observations were obtained through field work done under an 

 ONR contract, which calls for a reconnaissance survey of the geography of the Pacific lowlands 

 of Colombia. 



The Pacific littoral of Colombia is characterized by two distinct coastal types: (1) A low, 

 alluvial coast, fringed by a dense mangrove swamp forest, stretches from the Ecuadorean border 

 northward for more than 400 miles to Cabo Corrientes. (2) From Cabo Corrientes to Panama 

 and beyond, the coast is mountainous; cliff ed headlands alternate with short sand beaches formed 

 in small coves. 



Only the low, swampy mangrove coast is considered here, for it presents special prob- 

 lems for travel and subsistence; such problems may be characteristic of most mangrove coasts 

 of the humid tropics. Moreover, low alluvial coasts are the least understood of all coastal types 

 in terms of physical processes and development. 



The mangrove swamp of the Pacific littoral of Colombia occupies the tidal fringe of a 

 narrow alluvial coastal plain. This plain, 5 to 30 miles wide, is being formed by material de- 

 posited by streams flowing from the western versant of the Andes. These streams carry an 

 enormous volume of water, and probably a large load, for they drain areas having an annual 

 rainfall of 200 to 400 inches. A large tidal range— an average of 10 to 12 feet— occurs along 

 this coast. 



Two types of mangrove swamp coast exist along the Colombian littoral: (1) One is char- 

 acterized by dense mangrove forest growing to the edge of the sea and fronted by extensive mud 

 flats at low tide. Such a coast occurs in areas protected from strong wave action, as in bays or 

 behind shoals, (2) The other type of mangrove coast is characterized by the development of 

 extensive sand beaches along the seaward edge of the forest. Such beaches occur in sections 

 of strong wave action and longshore currents. Sand for building of beaches comes mainly from 

 stream load, which is effectively sorted by wave action. Minor amounts of sand probably de- 

 rive from erosion of occasional small headlands that occur south of Cabo Corrientes, such as 

 that near Buenaventura. Approximately 45 percent of the mangrove coast of Colombia is 

 fringed by sandy beaches. 



VEGETATION ZONES ALONG THE COAST 



Along most of the mangrove coast there exists a definite zonation of vegetation associa- 

 tions inland from the shore. Each of these zones is related to given physiographic conditions, 

 and each presents peculiar problems for living and travel. These zones are as follows: (1) 

 The beach zone , with its low shrubs, creeping vines, and stands of coarse grass. (2) The 

 mangrove zone , which consists of dense tidal forest of various species of mangrove. These 

 line the lagoons immediately back of the beach, and continue inland for a distance of one-half 

 to two miles. This zone penetrates much farther inland along the lower parts of streams, where 



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