The Uruguay River response to the late twentieth-century land cover change

SAURRAL, R.; BARROS, V.; LETTENMAIER, D.

Foz do Iguazu

Taller; V Taller Internacional sobre Enfoques Regionales para el Desarrollo y Gestión de Embalses en la Cuenca del Plata; 2008

The Uruguay River basin has suffered extensive man-made deforestation, especially during the second half of the twentieth century, associated to the development of agriculture. Furthermore, streamflow and precipitation across the basin have increased during that same period. To assess the impact of the land use change between 1960 and 2000 over the river mean streamflow a distributed hydrology model was used. This model was calibrated and validated in the ‘90s decade and was also used to assess the sensitivity of the Uruguay River discharges to changes in precipitation, temperature and land use. Results indicate that land use change has potentially great impact in the River streamflow, likely exceeding potential impacts of precipitation and temperature changes that could be foreseen for this century. Hence, future Climate Change effects on the Uruguay River basin would be likely dominated by land use changes. However, according to the hydrology model simulations, changes in land cover during the late twentieth century led only to a faster runoff response and did not modify the mean streamflow. Therefore, the positive trend observed in the Uruguay River streamflow during the second half of the past century should be attributed to the increase in mean precipitation over its basin.