 |
| Titel |
Inclusion of potential vorticity uncertainties into a hydrometeorological forecasting chain: application to a medium size basin of Mediterranean Spain |
| VerfasserIn |
A. Amengual, R. Romero, M. Vich, S. Alonso |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1027-5606
|
| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 13, no. 6 ; Nr. 13, no. 6 (2009-06-17), S.793-811 |
| Datensatznummer |
250011897
|
| Publikation (Nr.) |
 copernicus.org/hess-13-793-2009.pdf |
|
|
|
|
|
| Zusammenfassung |
| The improvement of the short- and mid-range numerical runoff forecasts over
the flood-prone Spanish Mediterranean area is a challenging issue. This work
analyses four intense precipitation events which produced floods of different
magnitude over the Llobregat river basin, a medium size catchment located in
Catalonia, north-eastern Spain. One of them was a devasting flash flood –
known as the "Montserrat" event – which produced 5 fatalities and material
losses estimated at about 65 million euros. The characterization of the
Llobregat basin's hydrological response to these floods is first assessed by
using rain-gauge data and the Hydrologic Engineering Center's Hydrological
Modeling System (HEC-HMS) runoff model. In second place, the non-hydrostatic
fifth-generation Pennsylvania State University/NCAR mesoscale model (MM5) is
nested within the ECMWF large-scale forecast fields in a set of 54 h period
simulations to provide quantitative precipitation forecasts (QPFs) for each
hydrometeorological episode. The hydrological model is forced with these QPFs
to evaluate the reliability of the resulting discharge forecasts, while an
ensemble prediction system (EPS) based on perturbed atmospheric initial and
boundary conditions has been designed to test the value of a probabilistic
strategy versus the previous deterministic approach. Specifically, a
Potential Vorticity (PV) Inversion technique has been used to perturb the MM5
model initial and boundary states (i.e. ECMWF forecast fields). For that
purpose, a PV error climatology has been previously derived in order to
introduce realistic PV perturbations in the EPS. Results show the benefits of
using a probabilistic approach in those cases where the deterministic QPF
presents significant deficiencies over the Llobregat river basin in terms of
the rainfall amounts, timing and localization. These deficiences in
precipitation fields have a major impact on flood forecasts. Our ensemble
strategy has been found useful to reduce the biases at different hydrometric
sections along the watershed. Therefore, in an operational context, the
devised methodology could be useful to expand the lead times associated with
the prediction of similar future floods, helping to alleviate their possible
hazardous consequences. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|