Hydrometeorological analysis of a flash flood event in an ungauged Mediterranean watershed under an operational forecasting and monitoring context

Abstract

Abstract The current study presents the first attempt to investigate the November 2019 catastrophic flash flood in Olympiada (North Greece) under an operational forecasting and monitoring context, based on the mesoscale weather and research forecasting (WRF) model and the integrated multi‐satellite retrievals for global precipitation measurement (GPM‐IMERG) algorithm. When evaluated against ground‐based rainfall measurements, WRF showed an adequate predictive capability concerning the severity of the observed rainfall, even though the model's performance suffered from phase and spatial displacement errors. The GPM‐IMERG algorithm yielded the best performance in capturing the timing of the observed excessive rainfall. Concerning the hydrological outcome using the Hydrologic Engineering Center‐Hydrologic Modelling System (HEC‐HMS), a strong indication of the forthcoming flash flood could have been provided at least 2 days in advance based on the WRF‐based HEC‐HMS‐simulated flood peak (139.3 m3 s−1), as it was close to the drainage capacity of a constructed bridge in the plain stream bed, and to the 100‐year return period flood discharge.

Keywords

• flood
• forecasting
• GPM‐IMERG
• HEC‐HMS
• operational
• WRF