Applications of Close-range Imagery in River Research - Fluvial Remote Sensing for Science and Management - page 330

15

Applications of Close-range
Imagery in River Research

Walter Bertoldi 1 , Herv ´ePiegay 2 , Thomas Buffin-B elanger 3 ,
David Graham 4 andStephenRice 4
1 Dipartimento di Ingegneria Civile e Ambientale, Universita degli studi di Trento,
Trento, Italy
2 University of Lyon, Platform ISIG/ENS, Lyon cedex 07, France
3 Departement de biologie, chimie et geographie, Universit´eduQuebec a Rimouski,
Rimouski, Quebec, Canada
4 Department of Geography, Loughborough University, Leicestershire, UK

et al. 2008; Marcus and Fonstad, 2008, for recent reviews
of the topic). Optical imagery has traditionally been
collected from aerial platforms, mainly aeroplanes, but
also more recently using unmanned aerial vehicles that
allow surveys at sub-metre resolution (see Chapter 8) and
from elevated ground positions.
Airborne image-based methods of data collection have
a number of advantages over alternative field surveys
(see for example Lane et al., 1993). Amongst them, we
can cite: i) extended coverage with minimum effort in
comparison to field surveys, especially in remote areas;
ii) a well-developed methodology to obtain planimetric
measurements and digital elevation models from vertical
images (Lane et al., 1994; 1996); and iii) a resolution
that has no real limitations (Carbonneau et al., 2003).
Currently, conventional manned aerial platforms can
efficiently collect vertical imagery at spatial scales up to
that of the drainage basin and with a spatial resolution
down to 10 to 50 cm whereas unmanned platforms now
reach 1 to 10 cm.
However, aerial optical imagery has drawbacks that are
related to the platforms used to acquire the images. While

15.1 Introduction

The increasing spatial, temporal and spectral resolu-
tions of imaging technologies is improving our ability
to monitor river forms and processes, while more sophis-
ticated analysis of the imagery obtained is providing new
insights and understanding for river scientists. The speed
with which the changes have occurred has dramatically
increased in the last two decades. Introducing a recent
Special Issue of Earth Surface Processes and Landforms
dedicated to remote sensing of rivers, Marcus and Fon-
stad (2010) claimed that river remote sensing can be
considered as an emerging new sub-discipline in the river
sciences, promoted not only by the evolving methodolo-
gies, but also by the need for data describing a wide range
of spatial and temporal scales, that help practitioners plan
activities and target their actions.
Optical imagery is one of the most common remote
sensing tools that can be used with different platforms and
with different combinations of spatial resolution/covered
area (e.g. Lane, 2000; Butler et al., 2001; Mertes, 2002;
Gilvear and Bryant, 2003; Carbonneau et al., 2005; Feurer