Tuesday, 16 January 2007: 8:30 AM
Satellite rainfall estimates for real time flash flood guidance estimation
211 (Henry B. Gonzalez Convention Center)
In the aftermath of Hurricane Mitch's landfall in Central America in October 1998, and to provide early warning for a series of annual flash floods in the region, the development of a regional Central America Flash Flood Guidance (CAFFG) system was undertaken. The system was designed to produce in real time flash flood relevant information for more than 2,500 small catchments tiling Central America with an average catchment area of approximately 200 km2. The CAFFG system uses satellite rainfall estimates and telemetered on-site rain gauge observations, both in real time, to produce for each subcatchment 1-, 3- and 6-hour estimates of mean areal precipitation, 6-hourly estimates of depth-integrated soil moisture, and 1-, 3- and 6-hour flash flood guidance. In this context flash flood guidance is the volume of rainfall of a given duration over a certain catchment that is just enough to cause bankfull flow in the draining stream at the catchment outlet. The information provided by the system when used by experienced meteorologists and hydrologists with other real time information is adequate to support the development of nowcasts or short term forecasts of flash floods. The presentation will provide an overview of the prototype CAFFG system, and will focus on the satellite rainfall estimation component. In particular, bias adjustment algorithms will be reviewed and results of implementation will be presented. Overall system validation will also be discussed based on local reports of flash flood occurrence.