Geography Reference
In-Depth Information
1
Introduction: The Growing Use
of Imagery in Fundamental
and Applied River Sciences
Patrice E. Carbonneau 1 and Herv ´ePiegay 2
1 Department of Geography, Durham University, Science site, Durham, UK
2 University of Lyon, CNRS, France
traditional river sciences andmanagement. Consequently,
the authors argue that localised, non-continuous, sam-
pling of small scale river processes, forms and biota leads
to a fundamental scale mismatch between the processes
under scrutiny and our data collection. Fausch et al.
(2002) therefore argue that river sciences and manage-
ment must begin to consider and sample river catchments
(i.e. watersheds) at larger scales and that these units must
be considered more explicitly as holistic system.
The need to study and sample river catchments as holis-
tic systems naturally leads to the use of remote sensing as
a basic methodology. Remotely sensed data and imagery
is indeed the only approach which could conceivably give
continuous data over entire catchments (Mertes, 2002;
Fonstad and Marcus, 2010). However, in the 1990s and
early 2000s, existing remote sensing acquisition hard-
ware and analysis methods were neither tailored nor
very suitable to the needs and interests of river scien-
tists and managers. Mertes (2002) presented a review of
remote sensing in riverine environments at the turn of
the century. At that time, any data with sub-metric spatial
resolution was considered of 'microhabitat' scale. Conse-
quently, riverine features identified by remote sensing in
the late twentieth century were generally of hectametric
or kilometric scales. However, developments in the early
twentieth century proceeded at a rapid pace and our abil-
ity to resolve fine details in the landscape has dramatically
1.1 Introduction
Earth observation nowplays a pivotal role inmany aspects
of our lives. Indeed, hardly a day goes by without some
part of our lives relying on some form of remote sensing.
Weather predictions, mapping and high level scientific
applications all make intensive use of imagery acquired
from satellites, aircraft or ground-based remote sensing
platforms. This form of data acquisition which relies on
the reflection or emission of radiation on a target surface
is nowwell accepted as a standard approach to data acqui-
sition. However, the fields of river sciences and remote
sensing have operated independently during much of
their respective histories. Indeed remote sensing practi-
tioners generally consider streams as linear, or perhaps
network, entities in the landscape. In contrast, river scien-
tists such as fluvial geomorphologists, lotic and riparian
ecologists, with their focus on the internal structure of
rivers and the processes which create these structures,
often have a much more localised but three dimensional
view of river systems. Nevertheless, both modern fluvial
geomorphology and ecology are increasingly recognis-
ing that we need to reconcile these viewpoints. In a
seminal paper, Fausch et al. (2002) discuss the scien-
tific basis for this reconciliation. These authors argue
that natural processes, both biotic and abiotic, frequently
operate on larger spatial scales and longer time scales than
 
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