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| Titel |
Use of ASCAT derived soil moisture product for real-time flood forecasting in the Upper Tiber River |
| VerfasserIn |
Luca Brocca, Florisa Melone, Tommaso Moramarco, Wolfgang Wagner, Stefan Hasenauer, Nicola Berni |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250035595
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| Zusammenfassung |
| The role and the importance of soil moisture for meteorological, agricultural and hydrological
applications is widely acknowledged. In particular, for a given storm event, different values of
initial soil moisture conditions can discriminate between minor or catastrophic effects.
Therefore, a real time flood forecasting system founded on a rainfall-runoff model
strictly requires an accurate estimation of the initial state of the catchment wetness
to obtain a reliable estimation of the flood hydrograph. It has to be pointed out
that, in flood-prone areas, a Flood Monitoring and Warning System operating in
real time represents the main non-structural measure to be actuated to dampen the
risk.
At the catchment scale, soil moisture monitoring can be addressed by using sensors
operating on remote sensing platforms. Among them, the coarse resolution scatterometers
have been employed in different studies due to their high temporal resolution suitable for
hydrological applications. Specifically, the Advanced Scatterometer (ASCAT) on-board of
the Meteorological Operational satellite provides an operative surface soil moisture product
available at global scale since March 2007. This sensor is characterized by a spatial resolution
of 25/50 km and a nearly daily time step. To get profile soil moisture estimates, an
exponential filter is applied to the time series of the ASCAT surface soil moisture obtaining
the so-called Soil Wetness Index (SWI). The reliability of the SWI was recently evaluated
through the comparison both with in-situ and modelled soil moisture data in the Upper Tiber
River basin.
In this study, the effects of assimilating satellite-derived soil moisture estimates into a
continuous and distributed rainfall-runoff model, named MISDc, were assessed. This topic
is relevant not only for scientific purposes but also for operational applications.
In fact, the MISDc model is actually operative at the Umbria Region Functional
Centre for real time flood forecasting in the Upper Tiber River (~5300 km2). The
model is based on the coupling of a simple soil water balance and an event-based
rainfall-runoff model through an experimentally derived relationship. Therefore,
MISDc is characterized by a parsimonious structure and parameterization and, at
the same time, a high computational speed that is crucial for real time operational
purposes.
By using simple data assimilation techniques, the SWI derived by ASCAT was
assimilated into MISDc and the model performance on flood estimation, with and without
assimilation, was compared. In particular, two significant flood events occurred
on December 2008 and January 2010 that produced flooding and damages were
carefully investigated. Moreover, three synthetic experiments considering errors on
rainfall, model parameters and initial soil wetness conditions were carried out in
order to further ascertain the SWI potential when uncertain conditions take place.
Results reveal that the ASCAT soil moisture estimates can be conveniently used to
improve runoff prediction in the study area. These products become essential when
the soil wetness conditions before a storm event are highly uncertain or unknown. |
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