Deforestation and Climate Variability effects on the Araguaia River, Brazil

Deforestation is impacting river systems like the Araguaia, which forms a natural border between the Brazilian states of Goias, Mato Grosso, Tocantins, and Pará.  The Araguaia River is a rare example of rapid geomorphologic response of a large alluvial river to land cover and land use change.  Deforestation alters the hydrological, geomorphological, and biochemical states of streams.  This occurs due to decrease evapotranspiration and increased runoff, river discharge, erosion and sediment fluxes from the land surface.  Over the past 4 decades, Brazil has experienced rapid regional development and land use change due to high demand of cattle feed, beef, and other agricultural commodities like sugar cane.  At the same time during the 1990s parts of Brazil has experienced increases in precipitation.  Determining how river systems respond to multiple changes require further study to link and quantify land use change and geomorphic responses.

Professor Edgardo Latrubesse was a Co-Principle Investigator (PI)  of an international project in Brazil named “Land use Impacts on the Water Resources of the Cerrado Biome” which was supported by NASA, Earth Science Enterprises and developed in collaboration  the Wood Hole Research Center, University of Goias Brazil,  and University of Brasilia.  Professor Latrubesse, with an international team of researchers, studied the river’s watershed, relating land use change to geomorphic response in the river system.  Their results are reported in the Journal of Biogeochemisty which shows that agricultural expansion has impacted the system. The team used modeling methods to simulate the watershed without land cover change, which suggested that about 1/3 of the observed discharge increase in the 1990s can be attributed to the observed increase in precipitation (Climate Variability). The simulation with land cover change compared to that without land cover change in the 1990s suggested that the remaining 2/3 of the observed discharge increase was most likely the result of some other factor such as a net decrease in evapotranspiration that occurred when native vegetation was replaced with more shallow rooted, less water-demanding pastures and crops.

Their paper can be found at:

Coe, M. T., E. M. Latrubesse, M. E. Ferreira, and M. L. Amsler (2011), The effects of deforestation and climate variability on the streamflow of the Araguaia River, Brazil, Biogeochemistry, 1–13.