Hydrometeorological Modeling of the Extreme Rainfall Events during RELAMPAGO Campaign

SUJAN PAL; CARLOS M. GARCÍA; FRANCINA DOMINGUEZ; STEPHEN W NESBITT; JAVIER ALVAREZ; DAVID GOCHIS

San Francisco

Congreso; AGU Fall Meeting; 2019

Extreme rainfall events and associated flash flooding is one of the most pervasive weather-related natural hazard. Some of the world?s deepest and largest convective storms develop at the foothills of the Sierras de Córdoba (SDC) ? a mesoscale mountain range east of the Andes. These storms organize into MCSs and then travel toward the eastern part of Argentina impacting the Carcarañá River basin, which was the testbed for the RELAMPAGO (Remote Sensing of Electrification, Lightning and Mesoscale/ Microscale Processes with Adaptive Ground Observations) Project. RELAMPAGO was an international field campaign to observe the physical mechanisms that cause the initiation/growth and impacts of organized convective systems. The project took place near the SDC with an Extended Hydrometeorology Observing Period from 1 June 2018 ? 30 April 2019 and an Intensive Observing Period from 1 November ? 15 December 2018. The hydrometeorology group generated the stage-discharge curves of previously ungauged basins and measured the hydrologic response of several severe high flow events during the campaign. We used Acoustic Doppler Current Profiler to measure low flows and Large Scale Particle Image Velocimetry for high flows. The main objectives of these observations were to understand the response time of flash flood in different reaches in this previously un-gauged basin and build suitable rating curves for the three rivers ? Santa Rosa, Quillinzo and La Cruz. We also use WRF model, and its hydrologic model component WRF-Hydro to simulate two extreme events during the field campaign. Satellite observation product GPM IMERG, high-resolution reanalysis data ERA5 and GFS precipitation data were used to drive the models. Rain gauges and radar precipitation data were also analyzed. Response time in these rivers were typically 6-8 hours, depending on the intensity and spatial distribution of rainfall. Our results suggest that WRF and WRF-Hydro can realistically capture the precipitation and hydrologic response if proper initial and boundary condition and suitable model parameters are used. In particular, we find that lower-level moisture transport through the South American Low Level Jet is extremely important to initiate such events and hence, accurate representation of it in models is important to flood predictability in this region.