AGU: Geophysical Research Letters

 

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Fluctuations in Uruguay River discharge: Climatic variations or land use changes?

The Uruguay River basin has experienced extensive land change during the second half of the twentieth century as agricultural area expanded. Concurrent with this has been an increase of streamflow and precipitation due to atmospheric dynamics. To help determine which factor—land use change or atmospheric dynamics—has contributed more to fluctuations in Uruguay River discharge, Saurral et al. (2008) studied streamflow along the Uruguay River using a hydrology model run between 1960 and 2000 that explicitly accounts for the role of land cover. The authors found that increases in average streamflow are more likely attributable to climatic variations, implying that land use changes were not large enough to produce appreciable changes in basin runoff. This is perhaps because most land changes did not result from deforestation but instead involved converting grassland (pasture) to crops. However, the authors noted that basin response, namely, that flows at the basin outlet now occur about 2 days sooner than in the 1960s, appears to be attributable solely to land cover change between the 1960s and the 1990s.

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