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A STATE OF ART ON AIRBORNE LIDAR APPLICATION IN HYDROLOGY AND
OCEANOGRAPHY: A COMPREHENSIVE OVERVIEW
A. Mohammadzadeh a ’*, M. J. Valadan Zoej a
a Geodesy and Geomatics Engineering Faculty, K.N.Toosi University of Technology, No. 1346, Vali Asr St., Tehran,
Iran, Postal Code: 1996715433 - ali_mohammadzadeh2002@yahoo.com - valadanzouj@kntu.ac.ir
KEY WORDS: LiDAR Oceanography, Hydrography, Mapping, Bathymetry
ABSTRACT:
Nowadays, lidar has been accepted as one of the important sensors providing accurate and dense 3D point cloud from earth surface
terrain and water bathymetry. The basic idea of using lidar stems from the problem of measuring water depth without direct
contacting with the water body or without any instrument mounted on the water surface in shallow regions. Bathymetric lidar that
uses two different laser beam mounted on a flying aircraft above the water surface has proved to be a good solution. This ability
resolves many of the industrial and military needs for accurate and precise geospatial information from water body in shallow area in
a very rapid manner. This technology has been used in the cases which would be solved with serious difficulties using alternative
solutions. In addition to hydrology and- oceanography, there are other important application areas which mainly are urban mapping,
forestry, and photogrammetry. In this study, a comprehensive overview to the use of lidar technology in the oceanography and
hydrology is discussed. In ocean and hydrography, various subjects are tackled such as: dunes and tidal flats measurement, coastal
change and erosion, flood mapping and prediction, snow and ice measurement, water bathymetry in depths up to 70 m. Airborne
lidar systems are rapidly developing and expanding in new applications. Integration of lidar with imaging sensors, efficient using of
waveform information and better processing algorithms would make a great development in obtaining more realistic and accurate 3D
models of the geospatial objects. Maybe in future, more cost effective solutions would attract the users to suite from this technology.
1. INTRODUCTION
Currently lidar technology has been operational used in
different applications by many organizations and industries. In
some specific cases, using traditional methods would take a lot
of time and cost from the customers to fulfill their needs. For
instance, many hydrography and oceanography organizations
need bathymetric maps for near coastline area. Using echo-
sounders would be dangerous, not accurate enough in shallow
waters, time consuming, and do not give a continuous water
depth. Alternatively, using bathymetric lidar provide accurate,
continuous, fast depth information from a large region. There is
no need to contact directly with the water body and this ability
resolves many of the industrial and military needs for accurate
and precise geospatial information from water body in shallow
area in a very rapid manner. In this study, a comprehensive
overview to the use of lidar technology in the oceanography
and hydrology is discussed and various subjects are tackled
such as: dunes and tidal flats measurement, coastal change and
erosion, flood mapping and prediction, snow and ice
measurement, water bathymetry in depths up to 70 m.
2. LIDAR APPLICATIONS IN HYDROLOGY AND
OCEANOGRAPHY
Water hydrology modeling and watershed management is based
on constant monitoring of the water volume over a long time
for modeling water dynamic behavior. Flood prediction and
flood extend modeling is one of the most important issues in the
watershed management and usually the primary interest would
be coastal area and rivers hydrodynamic modeling especially in
the event of the flood. Remote sensing technology provides a
highly fast and rich source of data for the above mentioned
modeling which was lacking by other type of sources like
ground based methods. Previously due to the lack of
information, there was not good correlation between reality and
hydrodynamic models and also the models were not complete
enough. With the presence of Remote Sensing sensors huge
amount of data in short period of time is available for the
hydrologists and there is need to investigate the different
available RS data and their suitability. River and coastal
monitoring and modeling task require 3D information about a)
Coast or river bottom depth, b) coast or river surface and banks
topography (in the lowest water level), c) Vegetation height, d)
Man-made objects near to the coast or river, e) All the objects
that might have effect on the water current.
A number of RS sensors have the potential of providing the
data for the required mentioned factors and will be investigated
in the following judgment which is more a personal opinion.
Airborne multispectral images is capable of the recording the
backscattered sun beam from the river bottom surface. This
gives the possibility of indirect estimation of the water depth
through a regression model between image recorded radiation
and the in situ control information for validation of the model.
The practical models have shown that airborne optical
multispectral passive sensors demonstrate the depth
measurements up to 6 meters with 50 cm accuracy. One should
consider that data collected over turbid water and cloudy or
wavy areas makes these sensors inefficient. Automatically for
water depth more than 6 meters, the water clarity is not enough
for accurate depth measurement. For depth more than 6 meters,
other bathymetric sensors are used like radar images,
Hyperspectral airborne images, and Lidar. Vogelzang
(Vogelzang et al., 1994) proposed depth extraction from radar
intensity image using an numerical image inversion method
based on the fact that the water surface waves in low wind
condition is affected by the bottom topography which higher
magnitude surface waves result in high intensities and
