Geography Reference
In-Depth Information
6
The Use of Radar Imagery in
Riverine Flood Inundation
Studies
GuyJ-P.Schumann
1
, Paul. D. Bates
1
, Giuliano Di Baldassarre
2
and David C. Mason
3
1
School of Geographical Sciences, University of Bristol, UK
2
Department of Hydroinformatics and Knowledge Management, UNESCO-IHE,
Delft, The Netherlands
3
Environmental Systems Science Centre, University of Reading, UK
and aircraft carrying Synthetic Aperture Radar (SAR)
sensors are valuable as radar wavelengths can penetrate
cloud cover and obtain land cover information both night
and day (Woodhouse, 2006).
However, given the strong inverse relationship between
spatial resolution and revisit time for satellites, monitor-
ing floods from space in near real-time or operationally
is currently only possible through either low resolution
(about 100 m ground pixel size) SAR imagery or satellite
constellations. For instance, revisit times for SAR imagery
of
6.1 Introduction
Flooding is a major hazard in both rural and urban
areas worldwide, and has occurred regularly in the world
in recent times. Between 1998 and 2004, Europe suf-
fered over 100 major damaging floods, including the
catastrophic floods along the Danube and Elbe rivers in
summer 2002. Severe floods in 2005 further reinforced
the need for concerted action. Since 1998 floods in Europe
have caused some 700 deaths, the displacement of about
half a million people and at least
¤
25 billion in insured
economic losses (EC, 2011). In the UK, there was exten-
sive flooding due to extreme rainfall in the north and
west of England in the summer of 2007 that caused a
number of deaths and damage of over £3 billion. An
increasingly urbanised global population and the inter-
dependence of complex urban infrastructure means that
our vulnerability to such events is increasing.
Within the more recent scientific literature, dating
back ten years, it is recognised that remote sensing can
support flood monitoring, modelling and management
(Smith, 1997; Bates et al., 1997). In particular, satellites
∼
100m spatial resolution (usually termed wide swath
mode) are in the order of three days and the data can
be obtained within 24 h at low cost. Hence, this type
of space-borne data can be used for monitoring major
floods on medium-to-large rivers. For basin areas down
to around 10 000 km
2
flood waves usually take several
days to transit through the catchment river network and
there is thus a reasonable chance of floodplain inunda-
tion coinciding with a satellite overpass. In smaller basins
with shorter flood wave travel times the probability of
imaging a flood decreases proportionately and acquisi-
tions become increasingly opportunistic such that even
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