Airborne LiDAR Methods Applied to Riverine Environments - Fluvial Remote Sensing for Science and Management - page 138

7

Airborne LiDAR Methods
Applied to Riverine
Environments

Jean-St ephane Bailly 1 ,PaulJ.Kinzel 2 , Tristan Allouis 3 ,
Denis Feurer 4 and Yann Le Coarer 5
1 AgroParisTech, UMR TETIS and UMR LISAH, Montpellier, France
2 USGS, Geomorphology and Sediment Transport Laboratory, Golden, CO, USA
3 Irstea, UMR TETIS, Montpellier, France
4 IRD, UMR LISAH, Montpellier, France
5 Irstea, Unite de Recherche, HYAX, Aix-en-Provence, France

The American scientist Hulburt used these systems
in 1937 to measure air density profiles in the upper
atmosphere (Weitkamp, 2005, p.3). The first successful
ground-based ranging LiDAR system was developed by
Smullin and Fiocco (1962), who used it to measure the
distance between the Earth and the Moon. The first air-
borne LiDAR for earth surface observation was developed
in 1965 as a 'bathymeter' to locate submarines (Ott, 1965).
Today, LiDARs can be placed in four categories: elastic
scattering LiDAR, used in ranging applications; inelastic
or fluorescence LiDAR for chemical, composition or
concentration measurements; Doppler LiDAR for speed
measurements; and differential-absorption LiDARs for
gaseous species detection (Flamant, 2005, p. 871).
In this chapter, airborne LiDAR systems and experi-
ments conducted in riverine environments are presented,
specifically for bathymetry. In the first section, the the-
oretical background of airborne LiDAR is presented.
Examples of LiDAR system capabilities and practical
survey information are provided in the following two
sections. In the fourth section, the techniques used to
derive information from LiDAR signals within the scope
of riverine environments are explained. Two river survey
case studies are presented in the fifth section.

7.1 Introduction: LiDAR definition
and history

LiDAR is an acronym for Light Detection And Ranging.
Other names, such as ALSM (Airborne Laser Swath Map-
ping), LADAR (LAser Detection And Ranging), altimetry
laser, or laser scanner, are also used, though less fre-
quently. LiDAR is an active remote sensing technique.
The principles of LiDAR are quite similar to RADAR, but
instead of using radio wavelengths (1-10 cm), it oper-
ates in the infrared, visible, or ultraviolet wavelengths
of the electromagnetic spectrum (250 nm up to 11 m)

(Weitkamp, 2005, p.4). LiDAR systems include hardware
and software for analysing the properties of laser pulses
reflected from multiple surfaces back to the system by a
remote target. In a mono-static configuration, a LiDAR
system is composed of a laser transmitter, a telescope,
photo-detectors, and a computer.
LiDAR has its origins in the atmospheric sciences.
The early development of LiDAR instruments included
ground-based light pulse systems developed by the two
French meteorologists Barthelemy and Bureau in 1935, to
measure the elevation of clouds (Flamant, 2005, p.865).

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