The Magdalena River, along with its main tributary, the Cauca River, form a hydrographical basin of 272,000 km2 a unique in the world fluvial system, notable for its location in the tropics and its singular hydric and sedimentological production. The basin which has 24% of the continental area of the country also gathers 85% of the population of the second-most populated country in South America, despite being the fourth in size. The Magdalena-Cauca basin is notable for its biodiversity and ecosystem production and for its cultural, social, and economic conditions, which defines the nationality of Colombia.
For these reasons, the river deserves world attention to safeguard the natural resources of its basin and its environment, and hence improve the quality of life of the community, complementing its economic rates and international growth that do not reflect the real value of the environmental costs of development, critical to a country of the ecosystem wealth of Colombia, and whose preservation is directly related to the welfare of its inhabitants and real progress.
To judge the real socioeconomic, environmental and cultural significance of the Magdalena River, it is necessary to determine, at least in general terms, the environmental values of the rivers amongst the drinking and irrigation water, the esthetic issues, navigation, and recreational services among others1. Although the river has established some of its physical and hydraulic singularities, it is important to summarize all its physical, socio-cultural, and environmental features more in detail. (See table 1)
The backbone of the South American subcontinent is the Cordillera of the Andes, that goes from the Chilean Patagonia to the Colombian–Venezuelans Caribbean Sea, giving rise to the narrow but very important Pacific Ocean coastline, characterized by mangrove jungles of Ecuador, Colombia, and Panamá, and more to the south to the semi-desert beaches of Peru, and northern Chile and fiords and rocky coasts of southern Chile. However, the east produced the enormous hydrographical basins of the three greatest rivers in the world, Amazon, the Orinoco, and the Paraná.
Entering Colombia, at latitude 1° 55´N, the Cordillera of the Andes divides into the so-called “Nudo de los Pastos”, an intricate mountainous mass and producer of important fluvial currents with three branches that define the Colombian territory and also comprise two large Cauca and Magdalena River gorges, that get together at latitude 8° 55´N to give way to the 272,000 Km2 Magdalena – Cauca Basin. Although both rivers are morphodinamically different, the environmental conditions of their basins are similar and include 85% of the populated areas of the country, while the remaining 15% of the population is located on the western and eastern foothills of the orographic systems of the two sub-basins.
The Magdalena River crosses Colombia along 1,600km, through 22 of 32 Colombian provinces, 728 of its 1100 municipalities, and 596 within the specific Magdalena Basin.
The location of Colombia within the Tropical band and even in the narrow Equatorial band create a series of circumstances that dominate the weather and hydrology, producing the highest rainfall region of the planet, (the Urabá, close to the border with Panamá), and makes the Magdalena River one of the most mighty rivers of the world (the greatest water production per area unit in its basin), producing 29.6 lt./sec./Km2 as opposed to 3229.6 lt./sec./Km2 of the Amazon River and whose basin is 350 times larger. On the other hand, its sediment production reaches 661 tons/km2, the highest of any river in the world, against 125 of the Amazon River. (See Table 2)
The Magdalena River is not only the direct source of freshwater, irrigation, power generation, and industrial water supply for more than 50% of the population of the country, but its main tributary, the Cauca River, and other 30 tributaries, also do the same for 85% of the Colombian population.
In the same manner, along its trail, the river and its tributaries produce marshes, wetlands, and coastal lagoons of extraordinary hydrological, geomorphological, esthetic, and productive value, which are the base of one of the greatest eco-diversities in the world. We can highlight the Medio Magdalena and Bajo Magdalena marshes, the extraordinary aquatic world La Mojana, produced by the diffluence of both rivers, the Canal del Dique diffluence, the immense Ciénaga Grande de Santa Marta, one of the biggest coastal lagoons in the world with more than 480 km2 of water surface and several pile dwelling communities of considerable singularity 3.
The Magdalena River is also the backbone of the culture, development, and history of Colombia. Although the great orographic, jungle, fluvial, and marsh barriers maintained the country far from the expansionist forces of the Maya (to the north) and Inca (to the south) civilizations, the same geographic position on the northeastern corner of South America, allowed hosting and developing indigenous communities of undeniable anthropological and cultural value, that left an irremovable technological, artistic, and philosophical footprint.
From the indigenous cities of the Sierra Nevada de Santa Marta to the complex drainage systems and the prehispanic crops of the lower San Jorge4, diffluent of the Cauca River in the area of La Mojana, to the north, to the singular ancestral tombs and statues of Tierradentro and San Agustín, to the south, passing through Muisca Indian observatories, in the center and the indigenous cultures of the Magdalena Basin live up to today with their statues, monuments, temples, and unique pottery and gold work in the context of the American indigenous tribes.
The Magdalena River is threatened by those who want to force the uses of the river to satisfy only the economic claims of a few, against the welfare of a whole nation. The great threats that hover over the river are threefold: great dams and those proposed for the lower flows of the major tributaries; industrial navigation, based mainly in massive transportation of oil-based byproducts and mining, besides agricultural dangerous raw materials and deforestation and the speedy advance of the urban frontier and the large infrastructure works over marshland on the Caribbean Coast.
Both, the ecosystem production as the fishing volume have noticeably decreased and many animal and plant species have been lost without the protection from environmental agencies and corporations that do not exercise effective control of the deterioration.
For all the preceding, recently the Colombian legislation began an acknowledgment of rights of large rivers and many fauna species in danger of extinction. It would be very appropriate for the Magdalena River to be recognized as a subject of these rights and protected against the private and governmental depredation that is constantly threatening. The river needs to be researched and understood by nationals and foreigners alike and protected as a special patrimony of Colombia and humanity.
1 Ordóñez, J.I., Duque, R. “Valores Ambientales en los Proyectos Fluviales, Uso y Abuso de los Ríos”. Memorias, XXVII Congreso Latino Americano de Hidráulica de la IAHR. Lima, Perú, Agosto 2016.
2 & 3 Milliman J. D., Arnsworth, K.L. “River Discharge to the Coastal Ocean - A Global Synthesis”. Cambridge University Press, 2011.
4 Parsons, James. 1966. Los campos de cultivo prehispánicos del bajo San Jorge. Revista Academia Colombiana de Ciencias. Vol. XII, No. 48.
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