1. Implementation of the fully-distributed and physically-based FEST-WB model A. Amengual Grup de Meteorologia, Departament de Física, Universitat de les Illes Balears, Palma, Mallorca, Spain e-mail: arnau.amengual@uib.esarnau.amengual@uib.es Universitat de les Illes Balears Reunión PREDIMED 2014A 5-6 Junio

2. Implementation of the physically-based distributed FEST-WB model 1.Overview of the FEST-WB model 2.The Serpis flash-flood event 3.Preliminary results 4.Future tasks

3. 1. Overview of the FEST-WB model Flash-flood Event-based Spatially-distributed rainfall-runoff Transformation – including Water Balance Computes the main processes of the hydrological cycle: -Evapotranspiration -Infiltration -Surface runoff -Flow routing -Subsurface flow -Groundwater flow -Snow dynamics

4. 1. Overview of the FEST-WB model

5. Computational domain is meshed with a net regular square cells (200 meters) Continuous soil moisture accounting: Runoff is computed according to a modified SCS-CN method. Potential maximum retention, S, is updated as a linear function of the degree of saturation (ε): Actual evapotranspiration, EVT, calculated using the Hargreaves equation Surface and sub-surface routing: Muskingum-Cunge method in its non-linear form Reservoir: Flow routing is described using the level pool scheme.

6. 2. The Serpis flash-flood event: synoptic situation 1. Upper-level closed trough 2. Strong high pressures over Western Europe 3. Low pressures over northern Africa 4. Low-level jet: advection of warm and moist air toward Valencia from the Mediterranean 5. Orographic lifting (Sierra de Aitana)

7. 2. The Serpis flash-flood event: synoptic situation Quasi-stationary MCSs

8. Torrential precipitation took place on 11 and 12 October 2007 Accumulated precipitation amounts above 400 mm The Serpis catchment is a small size basin with an area of 752.8 km 2 and a length close to 74.5 km. Accumulated rainfall above 300 mm from 00 to 12 UTC 12 October 2007 inside this basin 2. The Serpis flash-flood event: observations

9. Peak discharges: Vernissa: Qp=315 m 3 s -1 Beniarrés: Qp=260 m 3 s -1 Carrós: Qp=200 m 3 s -1 1 fatality. 200 people evacuated 2. The Serpis flash-flood event: observations

10. 3. Preliminary results

18. 4. Future tasks How can we improve flash-flooding process knowledge and forecasting? 1. Which are the hydrological characteristics of extreme floods in the semi-arid Mediterranean environment? 1.1 To determine which are the main hydrological processes involved in flash-flooding for semi-arid river basins in the Mediterranean. 1.2 To assess which is the specific role of the infiltration mechanism, soil moisture content and Hortonian flow before flash-floods in semi-arid river basins. 2. How can we improve the hydrometeorological forecasting of flash-floods? 2.1 To study the predictability of high impact weather related to intense rainfall and flash-flooding. 2.2 To assess how meteorological uncertainties propagate through the hydrological models. 2.3 To examine flash-flood predictability through advanced ensemble prediction hydrometeorological systems.