Climate change impact on the hydrological balance of the Itaipu Basin

This study aimed at carrying out an assessment of the impact of climate change on water availability for the Itaipu hydrological basin, located on the frontier between Brazil and Paraguay, with particular reference to river runoff and hydropower. Climate data for the SRES future scenario A2 were generated for the Parana hydrological basin (which includes the Itaipu hydrological basin) and hydrological impacts were studied. Present and future rainfall data were downscaled from the Canadian General Circulation Model (CGCM) for the A2 SRES scenario (periods 2010-2040 and 2070-2100) on a local meteorological network covering the Itaipu hydrologic basin and used as driving parameters for the Sacramento hydrological model to estimate the river runoff. The results of this analysis for the first period have shown an unchanged average annual runoff as the effect of an asymmetric impact on a seasonal scale. Climate change resulted in a higher runoff in summer-spring, whilst runoff in winter-autumn was lower with respect to the baseline. The second period resulted in a general decrease in runoff on both seasonal and annual scales. Possible impacts on hydropower production are discussed.