TWENTY FIRST CENTURY PROJECTIONS OF EXTREME PRECIPITATIONS IN THE PLATA BASIN

VICENTE R. BARROS; CHRISTIAN GARAVAGLIA; MOIRA E. DOYLE

International Journal of River Basin Management

Taylor and Francis

Año: 2013 vol. 11 p. 373 - 387

1571-5124

Distributions of monthly rainfall averaged spatially over three regions of the Plata Basin (LPB) were projected for 2011-2040 and 2071-2100 using outputs of four regional climate models (RCMs) nested in three different general circulation models, run with the SRES A1B emission scenario. Tuning of simulations with observations was done at the control period 1981-1990. During the past 50 years, in part of LPB there was a positive trend in annual precipitation. Two of the models indicate the maintenance of this trend over the northeast of Argentina and south of Brazil, while over the southernmost region of LPB, all models show increasing precipitation throughout the 21st century. Trends are less ambiguous for extreme precipitation, especially in the southernmost part of LPB, where huge and long-lasting floods take place over plains with small drainage. Months with extreme precipitation in LPB present a pronounced annual cycle with higher frequency from October to April. According to the RCM projections this pattern would persist during the twenty first century. Although, other factors cannot be discarded, the projected trends towards higher extreme monthly precipitation seem to be caused by an increase of the moisture convergence in the lower atmosphere over the east of LPB.