WSN05, Toulouse, France, 5-9 September 2005 1/10
EVALUATION OF A NON-HYDROSTATIC
MESOSCALE MODEL FOR DISCHARGE
FORECASTING
K. Chancibault, V. Ducrocq, F. HabetsCNRM/GAME, Météo-France
S. Anquetin, G-M. SaulnierCNRS, LTHE
WSN05, Toulouse, France, 5-9 September 2005 2/10
INTRODUCTION
• Flash-floods in Southeastern France :– Quasi-stationnary MCS => high cumulative rainfall
amounts (>200 mm/day)– Small mountainous basins (200 – 2500 km²) =>
short lag-time (<12 hrs)
Meso-NHor
AROMETOPMODEL
Meteorological model Hydrological model
1-way
2-way
1. One-way coupling : 8-9 September 2002 case
2. Two-way coupling : configuration
• Next NWP models : non-hydrostatic high-resolution model (AROME)
WSN05, Toulouse, France, 5-9 September 2005 3/10
ONE-WAY COUPLING
• The hydrological model : TOPMODEL (Beven and Kirkby, 1979)– DTM : 50 m– 1 model / basin– 9 basins (200 km²- 2200 km²)– Calibration (4 parameters)– Time step : 1 hour– Areal rainfall depths
ARDECHEARDECHE
CEZECEZEGARDGARD
VIDOURLEVIDOURLE
*Vogüé
*St Martin
*Quissac
*Sommières
*Remoulins
*Alès*
Anduze
*Boucoiran*La Roque
WSN05, Toulouse, France, 5-9 September 2005 4/10
ONE-WAY COUPLING
Rainfall data• Simulated rainfall :
– Meso-NH (Lafore et al, 1998), non-hydrostatic mesoscale model at 2.4 km
– Same physical package and resolution as AROME
– Initial conditions : mesoscale initialization (surf obs + radar + IR sat data) from Ducrocq et al ( 2000)
• Interpolated (kriging method) rain-gauge data
5/10WSN05, Toulouse, France, 5-9 September 2005
ONE-WAY COUPLING
• Case study : 8-9 September 2002– 24 casualties– Damage : 1.2 billion euros
mm 10 50 100 200 300
12-22 UTC
+
12-22 UTC, 08/09/02
Phase I
Nîmes
22-04 UTC
+
22-04 UTC, 08-09/09/02
Phase II
Nîmes
04-12 UTC
+
04-12 UTC, 09/09/02
Phase III
Delrieu et al (2005)
Nîmes
Cumulated rainfall (Nîmes radar)
WSN05, Toulouse, France, 5-9 September 2005 6/10
ONE-WAY COUPLING
• Meso-NH simulations results mm
SIMU
OBS
Cumulated rainfall
Phase I: 12-22 UTC Phase II: 22-04 UTC
OBS
Phase III: 04-12 UTC
SIMU SIMU
OBS
WSN05, Toulouse, France, 5-9 September 2005 7/10
VidourleVidourle
GardGard
CèzeCèze
ArdècheArdèche
ONE-WAY COUPLING
• Meso-NH simulations results
mm
SIMU
OBS
Simulated rainfall depths errors on the phase I
Qui
ssac
So
mm
ière
s A
lès
And
uze
Bou
coir
anR
émou
lins
La
Roq
ue
Vog
üéSt
Mar
tin
100*obs
sim
sim
R
RR
Cumulated rainfall duringthe phase I
WSN05, Toulouse, France, 5-9 September 2005 8/10
ONE-WAY COUPLING
• Hydrological simulations results
Anduze (540 km²)
observed dischargesSimulated discharges from :
observed rainfallsimulated rainfall
Vogüé (620 km²)
WSN05, Toulouse, France, 5-9 September 2005 9/10
TWO-WAY COUPLING
• Configuration
Meso-NH or Arome
Routing
t = 5 minx = 2-3 kmL = 1000 km
ISBAt = 5 minx = 2-3 kmL = 1000 km
t = 1hx = 50 mL = 1 km
flux
TOPMODEL
Wmob
As
WSN05, Toulouse, France, 5-9 September 2005 10/10
TWO-WAY COUPLING
• Idealized simulation
TOPMODEL 50mVogüé
TOPMODEL 50m Anduze
Vogüé+
ISBA 2.5 km
Anduze+
330 /mm 25.0)( tWg
33/mm 01.0 Wg
Soil water horizontal distribution
coupleur
Soil waterincrement
0.47
0.45
0.43
0.41
0.39
0.37
0.35
0.33
0.31
0.29
m3/m3
WSN05, Toulouse, France, 5-9 September 2005 11/10
CONCLUSIONS AND OUTLOOKS
One-way coupling :• Discharge forecasting needs updated high-resolution
forecasted rainfall• Ensemble forecasting rainfalls to perform ensemble
discharges forecasting
Two-way coupling :• Soil water horizontal distribution was implemented in the
SVAT scheme• Soon, routing will be added discharge simulation• Sensitivity studies (e.g. time step, soil depth, …)• Validation for numerous basins of the Southeastern France
Applications Validation of high-resolution simulated rainfall Study of the feedback of hydrology to the atmosphere Evaluation of the 2-way coupling vs the 1-way coupling
