Watershed

Oral

394488 - Generation and verification of medium-range ensemble flood inundation forecast maps with a coupled hydrologic-hydraulic prediction system

Thursday, June 7
10:30 AM - 12:00 PM
Location: Greenway IJ
Co-Authors: Alfonso Mejia, University Park – Pennsylvania State University

We investigate the ability to enhance flood inundation forecast mapping at the medium-range (3-7 days) timescales through weather ensembles and statistically water surface elevation (WSE) postprocessing. To generate the flood forecast maps, a one-dimensional hydraulic model (HEC-RAS) is coupled to a regional hydrological ensemble prediction system (RHEPS). The RHEPS is comprised by: i) hydrometeorological observations ii) weather ensembles from the National Center for Environmental Prediction Global Ensemble Forecast System Reforecast version 2 (GEFSRv2); iii) distributed hydrological model (HL-RDHM); iv) quantile regression (QR) as the statistical postprocessor; and v) verification strategy. The coupled RHEPS-hydraulic system is tested in the tidal Delaware River near the City of Philadelphia, Pennsylvania. The approach is used to generate 2-hourly high-resolution flood inundation forecast maps at lead times from 1 to 7 days, over the period 2008-2013. We find that the raw ensemble flood inundation forecasts have higher skill than the deterministic ones. Furthermore, we find that statistical postprocessing improves the skill of the raw ensemble flood inundation forecasts, particularly at the later lead times. In conclusion, we find that the medium-range flood forecast mapping can be skillful, thus providing an alternative for representing and communicating medium-range forecasts.

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394488 - Generation and verification of medium-range ensemble flood inundation forecast maps with a coupled hydrologic-hydraulic prediction system



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