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Speaker: Professor Daniel Sempere-Torres
Director, Center of Applied Research in Hydrometeorology (CRAHI)
Universitat Politecnica de Catalunya, Barcelona Spain
Date: Tuesday, December 3, 2013
Place: NCAR Foothills Laboratory, Building 2, Room 1001
Heavy rainfall is the cause of a number of hazards affecting our society through its impact on outdoor activities and exposed infrastructure assets. Traditionally floods, and specifically flash floods, have been considered the main natural hazard directly caused by heavy rainfall, but this perception is evolving toward a new paradigm of "heavy rainfall induced hazards" that include other emerging socioeconomic interest areas requiring specific hazard assessment, like surface transportation and aviation, construction, agriculture, or recreation activities.
With regard to flash floods (i.e., torrential floods with response times between 15 minutes to a few hours caused by intense rainfall that can accumulate over 25% of the annual rainfall in a few hours), the main requirement is to anticipate the occurrence of heavy rainfall with high spatial and temporal resolution for providing an appropriate hazard assessment to be used by the weather services, civil protection authorities, emergency managers or directly by the concerned public.
The advancements of the last decades in rainfall forecasting with numerical weather prediction models have been paired with advancements of techniques to improve very short-term rainfall forecasting (called nowcasting) using radar rainfall mosaics. The high-resolution of radar-based estimates enables capturing the short-term evolution of the rainfall pattern, which makes this a crucial source of information to anticipate potential impacts. In the last few years there have been a number of applications showing that radar-based rainfall nowcasting can be successfully applied even to continental radar networks, as those in the USA and Europe. Nevertheless, the transformation of these improved high-resolution rainfall nowcasts into efficient hazard assessments remains a primary challenge.
A number of recent European projects have been targeting a sensible strategy for how to deal with this challenge and to develop a number of tools supporting the above paradigm shift in the framework of implementing a European Flood Directive and Flood Risk Management Plans for prevention, protection and preparedness by 2015.
The basic concepts of the proposed methodologies, as well as the main results obtained over selected case studies will be the central point of the presentation.