Abstract

RESTREPO A., Juan D.. The impact of deforestation on the erosion in the Magdalena River drainage basin (1980-2010). Rev. acad. colomb. cienc. exact. fis. nat. [online]. 2015, vol.39, n.151, pp.250-267. ISSN 0370-3908.  https://doi.org/10.18257/raccefyn.141.

During the last decade, the Magdalena River drainage basin has witnessed an increase in erosion rates of 34%, from 550 t km^-2 y^-1 before 2000 to 710 t km^-2 y^-1 for the 2000-2010 yr-period, and the average sediment load for the whole basin increased in 44 Mt y^-1 for the same period. Sediment yield spatial analysis indicated that 78% of the catchment is under strong erosional conditions due to the clearance of more than 60% of the natural forest between 1980 and 2010. Sediment load simulation by using the BQART, a robust model that combines climatic, morphometric, hydrological, lithologic and human induced variables, and explains 86% of the sediment load variability, indicated that 9% of the combined sediment load during the last three decades was due to deforestation; about 160 Mt have been produced by forest clearance between 2000 and 2010. The trends in economic indicators show that agriculture was the main cause of land-use change and, consequently, of forest loss within the basin. Soil deterioration and increasing trends in erosion require capacity building in environmental governance in addition to climate change mitigation policies.

Keywords : Magdalena River; deforestation; sediment load; erosion.

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