Ground based LiDAR and its Application to the Characterisation of Fluvial Forms - Fluvial Remote Sensing for Science and Management - page 313

14

Ground based LiDAR and its
Application to the
Characterisation of Fluvial
Forms

Andy Large 1 and George Heritage 2
1 School of Geography, Politics and Sociology,
Newcastle University, UK
2 JBA Consulting, The Brew House, Wilderspool Park, Grenalls Avenue,
Warrington, UK

Hodge et al., 2009a, 2009b; Milan et al. 2010). The use
of oblique laser scanners to generate detailed DEMs of
landforms represents a major improvement on previous
surveymethods, both in aerial coverage and accuracy. This
chapter demonstrates this primarily through a review of
previously published material involving use of ground-
based laser scanning in fluvial studies, covering spatial
scales from centimetres to kilometres and daily to annual
change timescales.
Areal coverage, data point density, data point accu-
racy and their relationship with field survey and post-
processing time are particularly important when viewed
alongside the range of spatial and temporal changes within
fluvial systems where a general negative relationship exists
between scale of change and rapidity of change (Knighton,
1998). Many studies are limited by area or resolution
limitations due to a trade-off between spatial coverage
and morphologic detail captured (Large and Heritage,
2009); techniques such as terrestrial photogrammetry
produce high point density, accurate morphometric data,
but aerial extent is restricted; aerial photogrammetry
offers increased spatial coverage but reduced elevation

14.1 Introduction

While significant progress has beenmade in river research
over the past two decades using digital elevation models
(DEMs) to study stream processes, the accuracy of these
traditional DEMs varies spatially as map contour interval
and density dictate the resolution of information available
to interpolate an elevation value for each pixel on the grid
(Snyder, 2009). Inparticular, traditional DEMsmissmany
fine-scaled features, particularly those in low-relief terrain
such as river valley floors. In contrast, both airborne
and terrestrial laser scanning or LiDAR equipment and
software permits the construction of very detailed DEMs
that accurately represent such fine-scale landform surface
variability and in turn offer an excellent opportunity
to measure and monitor morphological change across
a variety of spatial scales (e.g. Brasington et al., 2000;
Lane and Chandler, 2003; Fuller et al., 2003; Hopkinson
et al., 2005, 2009). As a result, new insights are emerging
concerning river systemfunctionutilising digital elevation
models of the riverine environment (e.g. Lane et al., 1994;
Milne and Sear, 1997; Heritage et al., 1998; Brasington
et al., 2000; Poole et al., 2002; Large and Heritage, 2007;