Hydrological modeling of the Uruguay River with convection permitting dynamical downscaling

DOYLE, MOIRA EVELINA; DIAZ, GONZALO M; BETTOLLI, MARIA LAURA; SOLMAN, SILVINA; PORFIRIO DA ROCHA, ROSMERI; FERNANDEZ, JESÚS; MILOVAC, JOSIPA; COPPOLA, ERIKA; RAFFAELE, FRANCESCA; BALMACEDA HUARTE, ROCIO; OLMO, MATIAS

Congreso; VII CPCM 2023; 2023

The second objective of the CORDEX Flagship Pilot Study in Southeastern South America (FPS-SESA) proposed to develop actionable climate information from statistical and dynamical downscaling based on co-production with the impact and user community. As a result, new RCM simulations were designed for the planned impact studies of streamflow modeling of the Uruguay river. A 3-year time period, June 2018 to May 2021, was selected to study the ability of convection-permitting (CP) RCM simulations outputs to reproduce the Uruguay River streamflows when used to feed the Variable Infiltration Capacity (VIC) hydrological model. During these 3 years extremely dry conditions developed and persisted over the basin with high impact on water resources in the region including very low streamflows. Nonetheless, extreme precipitation events were also observed during warm months, which makes this period particularly interesting to study extreme discharges through hydrological modeling. The outcomes of the second phase of the FPS-SESA initiative provide four CP simulations conducted with WRF and RegCM5 RCMs, to which we have added simulations with NCAR WRF provided by SAAG. Daily outputs of precipitation, maximum and minimum temperature from all models as well as ground based observations and ERA5 data were used to force VIC to simulate discharges in the Uruguay River which were compared with observed discharges at 7 gauge stations distributed along the upper, middle and lower basin. Results evidenced the need to produce multi-model simulations to account for different uncertainty sources.