Flash Flood Forecasting Using Weather Radar and Satellite Data for Urban Catchment in Rio De Janeiro (PAP014783)
Luiz Carlos Salgueiro Donato Bacelar, Javier Tomasella, Helio Camargo, Carlos F. Angelis
Flood forecasting and early warning systems
According to the World Meteorological Organization, flash floods are the most lethal form of natural hazard (based upon the ratio of fatalities to people affected), and cause millions of dollars in property damage every year. This type of hydrometeorological disaster depends on land surface and atmospheric specifics conditions. A combination of a high rainfall rate with rapid and often efficient runoff production process is common to most events. In Brazil, flash floods can be deadly. Recently in January 2011, landslides, debris flow and flash flood processes in the mountainous region of Rio de Janeiro caused more than 900 fatal victims. During 3 days, the rainfall achieved almost 400 mm, a rate 71% higher than the month average. Despite the significance of these events, few countries in the world have already implemented flash flood warning systems. This is due in part to the technical complexity of predicting extreme events with enough confidence and lead time to take precautionary action. Since flash floods processes happen in the same temporal and spatial scale of severe storms, this paper aims to provide analyses of case studies simulating real-time flash flood forecasting, with high resolution weather radar and satellite rainfall estimates in an urban catchment in Nova Friburgo, Rio de Janeiro. Results indicate that at least some of flash floods can be predicted by the physically based distributed hydrologic modeling, even for shot-lived events on small catchments. Based on the limited observations available, validation indicates that there is good agreement of rising limb of hydrograph between simulated peak discharge and peak discharge observed. This technique has been developed by the Brazilian Centre for Monitoring and Warnings of Natural Disaster (Cemaden) and will be tested in operational environment for pilot catchments in following rainy season, improving flash floods early warnings in Brazil.