A combining analysis of three Catastrophic Precipitating Events over Western Mediterranean region

A combining analysis of three Catastrophic Precipitating Events over Western Mediterranean region

Nuissier, O.; Ducrocq, V.; Sandrine, A.

TU Braunschweig

Floodsite

2006-03-23

Within the framework of FLOODsite, specific attention is dedicated to improve our understanding of flash flood. Flash floods differ markedly from floods occurring on larger basins with larger time characteristics. Flash floods are produced by rain accumulations of typically more than 200 mm during less than 6 hours over natural watersheds ranging in area from 25 to 2500 km2. The rising rate of waters of several m.h-1 and the flow velocities of several m.s-1 make these floods extremely dangerous for human lives. Research on flash floods requires a mobilisation of activities and resources at the European level for at least four reasons: i. Flash floods are rare event. In Europe one or two flash floods per year have dramatic consequences. Probably ten times more cases of storms of comparable severity occur during the same period. ii. Flash floods are ill documented events. Each country has its own investigation and archiving rules frequently separating the meteorological and hydrological aspects. iii. The forcing meteorological situations and their climatic trend develop at the continental scale. iv. Socio-economic short and long term strategies mitigating flash floods need to be harmonized across Europe. Within this general context, this report aims at presenting the main results obtained within Action 1.1 of Task 1. Here, the main objective is the understanding of the meteorological processes that govern flash-flood driven storms. Three cases typical of flash-flood (described section 2) occurring in Western Mediterranean are simulated using the local research model MesoNH (section 3). After identifying synoptic scale factors that favour development of quasi-stationary mesoscale convective systems, sensitive experiments together with Lagrangian trajectory analyses have been performed to identify the role of the orography, of the low-level jets and of the convection itself in maintaining stationarity on the simulated storms and its resulting cumulated surface precipitation.

flash flood
flash flood
hydrometeorological monitoring

TPE700100

http://resolver.tudelft.nl/uuid:1d3b9f5f-e111-416f-a34a-0068a5abce41

MeteoFrance

T01-05-12

Hydraulic Engineering Reports

report