Geography Reference
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(2012) present a comprehensive dataset comprised of
particle sizes, channel widths, channel depths and slopes
all sampled continuously at metric resolutions for an
entire river. Faced with the complexity of the data the
authors have proposed new analysis methods aimed at
synoptic views and multiscale analysis of river variable
response along both the length and width of the river (see
also Figure 9.15 in Chapter 9 of this volume). One of the
observations of Carbonneau et al. (2012) is a frequent lack
of agreement between the data and established theories,
the authors therefore argue that such hyperspatial data
challenges current paradigms in river sciences. Continu-
ous data collection over the fluvial continuum provides
exceptional information to explore the network structure
in a multi-scale context which opens discussions on the
'scalar dissonance', the idea that the different scale levels
are not nested in each other but disjointed; the boundaries
of units at each scale level not being overlain (Leviandier
et al., 2012). The hierarchical theory as described by Fris-
sell et al. (1986) can be now explored, validated or, if
warranted by the evidence of real data, reformulated.
Such a widening application of fluvial remote sensing
to a greater number of catchments and rivers highlights
another challenge currently faced by the discipline: widen-
ing the user base and moving this technology beyond the
quasi-exclusive use of its developers. If we examine the
fluvial remote sensing literature discussed in Chapter 1,
we find that the vast majority of contributions were
made by the scientists responsible at least partially for the
methodological development. Rarely do we see a contri-
bution where an explicit thematic question is solved using
established remote sensing methods. Most of the time,
contributions explored the method itself or the capacity
of a given technology or a specific type of data to answer
the question. Moreover, most of the river management
initiative in Europe, following the implementation of
the Water Framework Directive, are based on field mea-
sures, sometimes combined with GIS information but
never with Remote Sensing information (e.g. The River
Habitat Survey in the UK or the QualPhy or SEQphy
methods in France). This is representative of a slightly
worrying gap between the developers and proponents of
this new technology and the potential users. Indeed, the
potential of fluvial remote sensing in river management
is still underexplored because practitioners still consider
these techniques as complex approaches which are not
traditionally taught and thus reserved to academic cir-
cles. However, we note that even within academic circles,
lotic ecologists rarely use fluvial remote sensing methods
as data sampling method. It is therefore becoming clear
that the dissemination of fluvial remote sensing methods
within a broader community of users is an urgent matter.
This is certainly not an impossible tasks since the raw
cost of imagery is at an all-time low and many fluvial
remote sensing tools are quite compatible with GIS pack-
ages already widely used. For example, the freely available
'River Bathymetry Toolkit' offers users of the EAARL
system for bathymetric river topography measurements
i.e. (McKean et al., 2009) a set of tools which are seam-
lessly integrated into the popular ArcGIS software. The
river bathymetry toolbox also comes with a range of
web based tutorial services such as YouTube videos and
html help files. Such open source approaches are needed
in order to facilitate the teaching and dissemination of
fluvial remote sensing to academics outside the remote
sensing community and river managers. Nevertheless, we
can argue this evolution is ongoing with the emergence
of private companies providing more and more frequent
airborne imagery campaigns but also LIDAR surveys to
help designing river management plans.
The wider availability of fluvial remote sensing to a
broad range of users would be a very powerful tool. It
could allow for the development of new procedures and
methods for automating and analysis data for describing
the state of biotic and abiotic features and for provid-
ing query procedures vitally needed in order to target
management actions in a period where maximum impact
must be reached at minimal costs. These tools could
also be used to predict the evolution of the managed
system thus allowing for risk analysis (e.g. assess sen-
sitivity of the system to change, assess potential effects
of given actions or pressures on channel network char-
acters), such as shown in Chapters 11 and 12, and for
an a priori evaluation of long-term costs. Furthermore,
these methods could provide crucial support to monitor-
ing efforts needed to survey fish populations, restoration
work evolution, pollution, natural hazards, ice cover and
even invasive species. Additionally, as demonstrated by
Chapter 18, river imagery has a role to play in the social
aspect of river restoration and could thus contribute to a
better integration of the socio-economic aspects and the
traditional biophysical aspects of river sciences. In such
context, the development of the 3D approaches which
allow people to interact and evaluate river aesthetics in a
virtual environment should provide also new indicators
and new opportunities to view the river corridors pro-
viding a bridge between biophysical characterisation and
social perceptions.
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