Geoscience Reference
In-Depth Information
continuous occurrence of disastrous landslide events has increased the demand for
new and improved techniques for landslide monitoring and analysis.
The Global Navigation Satellite Systems (GNSS), namely—GPS, GLONASS,
Galileo, Compass, QZSS and IRNSS are now being utilized as global infrastruc-
ture for a wide range of applications. The Global Positioning System (GPS), in
particular, has been widely used in monitoring the dynamics of landslide. GPS has
been employed in landslide monitoring based on the type of monitoring cam-
paigns, namely, periodic (Rawat et al.
2011
; Wang
2012
; Yalçinkaya and Bayrak
2002
) and continuous (Wang and Soler
2012
; Xiao et al.
2012
). These studies
highlight the critical factors in the choice of a particular monitoring campaign,
which include accuracy, cost, and safety of equipment. Some studies in landslide
monitoring have used GPS to compare results from conventional surveying or
geotechnical methods, such as theodolite, Electronic Distance Measurement,
levels, total station, inclinometers, and wire extensometers (Bertachini et al.
2009
;
Calcaterra et al.
2012
; Coe et al.
2003
; Gili et al.
2000
; Malet et al.
2002
; Moss
2000
; Rizzo
2002
; Tagliavini et al.
2007
).
Other studies have integrated GPS and other surveying techniques, namely,
terrestrial laser scanning, SAR interferometry, and photogrammetry, to investigate
the landslide phenomenon (Mora et al.
2003
; Peyret et al.
2008
; Rott and Nagler
2006
; Wang et al.
2011
). This combination provides valuable information on the
magnitude and direction of the displacements, total volume of the moving mass,
and the evolution of the landslide process. Some studies have investigated the
accuracy of low-cost single-frequency GPS receivers for landslide monitoring
(Janssen and Rizos
2003
; Squarzoni et al.
2005
). Finally, GPS has been employed
in landslide monitoring based on different GPS techniques, namely, static (Brunner
et al.
2007
), rapid-static (Hastaoglu and Sanli
2011
), real-time kinematic, RTK
(Wang
2011
), and based on the comparisons of these techniques (Othman et al.
2011a
,
b
).
The main goal of our ongoing research is to design a low-cost monitoring
system for landslide investigation using the RRTK technique. Some of the
advantages of RTK GPS which can be utilized for landslide monitoring application
include (Mekik and Arslanoglu
2009
): (1) post-processing is not required, (2)
acquired coordinates of points can be easily transformed to local coordinate system
in real-time, and (3) it is a reliable tool for monitoring multiple number of points—
increasing productivity and saving cost. For a standard RTK-GPS operation, dual-
frequency geodetic-grade receivers with the supporting firmware are usually
required. However, the high cost of these receivers and the supporting software is
one of the reasons limiting the use of RTK GPS for several monitoring applica-
tions (Takasu and Yasuda
2009
). Due to the harsh operational environment fre-
quently faced during landslide monitoring, coupled with security concern and the
prospect of losing the equipment during landslide event, the needs for low-cost
monitoring equipment are imperative.
The big challenge, therefore, in GNSS monitoring is how to reduce the cost of
the monitoring scheme. The cost of monitoring includes the costs of RTK GPS
receivers, power supply, communication, logistics, and personnel. Several authors
