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The Impact of Tropical  Deforestation on River Chemical Polution  

The Impact of Tropical Deforestation on River Chemical Polution

The objective of this study was to provide a quantitative description of the impact of converting tropical forests into pastures for cattle grazing in terms of the sediment, nitrogen and phosphorus concentrations at the outlet of a river basin located in North West Costa Rica. The Soil and Water Assessment Tool (SWAT) was utilized to model the watershed. The graphs for pollutant concentration vs. percent area of the watershed under pasture showed a monotonic increase in concentrations as deforestation increased. Contaminant levels for the entire watershed as grassland were between 3 and 8 times higher than for the total area as forest, which could put at risk the drinking water supply and the tourism-based economy of the region. Keeping the current percentage of area under grassland constant, but restricting pastures to the less fragile and more fertile lands could decrease the sediment, nitrogen and phosphorus concentrations at the main watershed outlet by more than 35%, 12% and 21%, respectively, as compared to the predicted pollutant concentrations for the current land cover distribution. The effect of varying cattle stocking rates resulted in lower sediment and nitrogen run-off for areas with higher animal loads in which confined operations are used part of the year.

Published by: Global Network for Environmental Science and Technology (GNEST) -
Uploaded on: Feb 2008
File size: 227 KB - Language: English
Keyword(s): Environment
Category: Environment

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