1 / 13

A. Amengual and V. Homar

Universitat de les Illes Balears. Reunión PREDIMED 2014A 5-6 Junio. Hydrometeorological ensemble forecasts for the 28 September 2012 (IOP8) extreme flash-flood in Murcia, Spain. A. Amengual and V. Homar. Grup de Meteorologia, Departament de Física,

lovie
Download Presentation

A. Amengual and V. Homar

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Universitat de les Illes Balears Reunión PREDIMED 2014A 5-6 Junio Hydrometeorological ensemble forecasts for the 28 September 2012 (IOP8) extreme flash-flood in Murcia, Spain A. Amengual andV. Homar Grup de Meteorologia, Departament de Física, Universitat de les Illes Balears, Palma, Mallorca, Spain e-mail: arnau.amengual@uib.es

  2. The Guadalentín flash-flood event • Hydrological and meteorological tools • Probabilistic versus deterministic QPFs • Probabilistic versus deterministic QDFs • Conclusions and further remarks Hydrometeorological ensemble forecasts for the 28 September 2012 (IOP8) extreme flash-flood in Murcia, Spain

  3. Entrance of a deep upper- • level closed trough • Generation of a surface • mesoscale cyclone • Advection of warm and • moist air toward Almería and Murcia from the Mediterranean • Convergence zone between • easterly advection and • westerly low-level flow • + • orographic enhancement • quasi-stationary mesoscale convective system 1. The Guadalentín flash-flood event: synoptic situation H500+T500+PV250 T850+SLP 27 September 2012 12 UTC 28 September 2012 12 UTC

  4. 1. The Guadalentín flash-flood event: observations • Torrential precipitation took place on 27, 28 and 29 September 2012 • Daily precipitation amounts: 214 mm in Andalucía, 240 mm in Murcia and 230 mm in Valencia • The Guadalentín catchment is a medium size basin with an area of 3343 km2and a length close to 121 km • Accumulated rainfall in 8 h up to 214 mm inside the basin • Peak discharges: • 616.3 m3s-1 in Lorca • 1081.2 m3s-1in Paretón de Totana

  5. 1. The Guadalentín flash-flood event • 10 casualties. Material losses estimated at about 120 M€

  6. 2. Hydrological and meteorological tools • WRF model set-up • Initial and boundary conditions: ECMWF forecasts (update 6h, 0.3º; 62 vertical levels) • One domain: 4 km and 28 vertical eta-levels • Schemes: Microphysics ─ WSM6; Long-wave radiation ─ RRTM ; Short wave radiation ─ Dudhia; surface model ─ NOAH; time-step ─ 30 s • The experiments consider a 48 hperiod simulation (27/09/2012 - 29/09/2012 00 UTC) • HEC-HMS model set-up • Loss rate: Soil Conservation Service Curve Number (SCS-CN) model • Transform: SCS Unit Hydrograph model • Flow routing:Muskingummethod • Reservoirs: elevation-storage-outflow relationship + initial elevation of the water level • The experiments consider a 72 hperiod simulation (27/09/2012-01/10/2012 00 UTC)

  7. 2. Hydrological and meteorological tools

  8. Guadalentín NSE EV (%) EP (%) rain-gauges 0.91 -5.7 -2.6 control 0.12 -88.4 -89.9 3. Probabilistic versus deterministic QPFs Flow observations only available for this study case: perfect-model assumption. Optimal estimation of the initial conditions and dynamical formulation after calibration. Difficulties to correctly forecast precise location and timing of convectively-driven rainfall system affecting a medium size basin

  9. 3. Probabilistic versus control QPFs • Mesoscale EPS (WRF) • Diversity source only from IC/BC (dynamical downscaling) • Obtained from ECMWF-EPS forecast (Global Singular Vectors) • 50 equally-likely members • Studyof the spatial and temporal uncertainties of QPFs into a medium-sized catchment

  10. 3. Probabilistic versus control QPFs • WRF ensemble comprises 51 elements (control + 50 perturbed) • Important spread on rainfall values • Essential role of atmospheric dynamical forcing (c) Ensemble mean ( in mm, shaded) and standard deviation (in mm, continuous line starting at 10 mm interval) (d) Probability-matched ensemble mean

  11. 4. Probabilistic versus deterministic QDFs • Elements of the HEPS are considered equally-like • Cumulative distribution functions (CDFs) of driven runoff peak flows

  12. 4. Probabilistic versus deterministic QDFs • Elements of the HEPS are considered equally-like • Cumulative distribution functions (CDFs) of driven runoff peak flows

  13. 5. Conclusions and further remarks • WRF control simulation is deficient for the Guadalentín event: maximum precipitation amounts are obtained quite far away from the basin • EPS reduce biases obtained for the control forecast • For civil protection purposes, a hypothetical first warning for a peak flow exceeding • Qp (T = 25 yrs) would have produced a probability of exceedenceof 0.4 and 0.3 at Lorca and Paretón. This fact points out the benefits of a HEPS versus a deterministic prediction system • The performance of the hydrometeorological simulations strongly depends on the initial conditions of the databases and on the case under study • References: • Amengual et al. (2014): Hydrometeorological ensemble forecasts for the 28 September 2012 (IOP8) extreme flash-flood in Murcia,Spain. Quart. J. R. Meteorol. Soc [submitted]

More Related