LANDSLIDE ASSESSMENT BY USING DIGITAL PHOTOGRAMMETRIC
TECHNIQUES
F. Karsli**, A. Yalcin*, M. Atasoy“, O. Demir“, S. Reis“, E. Ayhan“
^K TU, Engineering and Architecture Faculty, 61080 Trabzon, Turkey
(fkarsli, ayalcin, amustafa, odemir, sreis, eayhan)@ktu.edu.tr
Commission VII, WG VII/3
KEY WORDS: Landslides, Photogrammetry, Imagery, Environment, Geomorphology
ABSTRACT:
Landslide is one of the most costly and damaging natural hazards of the world, and has direct and indirect influence on a number of
human activities. The term landslide includes a wide range of mass movement, such as rock falls, deep failure of slopes and shallow
debris flows. Aerial imagery is a very powerful tool for landslide monitoring because it offers a synoptic view of landslide that can
be repeated at different time intervals. This study focuses on the application of landslide activity maps created by digital
photogrammetric techniques for evaluating the mass movement hazard in selected areas of the Northern East Turkey: Rize and
surrounding. The availability of multi-year aerial photo coverage helped to assess the morphological changes, which occurred in the
last seven years. This information, integrated with historical data on slope instability and field checks, was used to produce landslide
activity maps. The morphological changes have been revealed from aerial images that are belonging to 1996 and 2002 years. For the
evaluation of the aerial images, stereo photogrammetric software by Z/I Imaging was used. From the images that are belonging to
1996 and 2002. years, digital terrain models and vector map, which are containing the landslides area, were determined by using
mentioned software. The landslides have been occurred very wide areas in the study area at 2001 year. In this study, the parameters
that landslides occurring have been determined and environmental impacts of the landslides have been fixed. In addition, threatening
areas of landslides have been resolved with separately. As result, it is presented to have determined the landslides effects in
combination with image data and geomorphological data.
1. INTRODUCTION or deformation at very specific locations in active landslides,
especially when they might affect residential areas or major
Landslides, as one of the major natural hazards, account each infrastructure, they do not provide information on the
year for enormous property damage in terms of both direct and displacement fields or surface changes due to landsliding in a
indirect costs. Landslides, defined as the movement of a mass wider .area. Moreover, their application to preliminary
rock, debris or earth down a slope (Cruden, 1991), can be investigations of unstable areas may sometimes not be cost
triggered by a variety of external stimulus, such as intense effectives (Hervas et al., 2003).
rainfall, earthquake shaking, water level change, storm waves or
rapid stream erosion that cause a rapid increase in shear stress Photogrammetry is a technique whereby information about the
or decrease in shear strength of slope-forming materials. In position, size and shape can be attained. Photogrammetric
addition, as development expands into unstable hillslope areas products refer almost exclusively to the object space (maps,
under the pressures of increasing population and urbanization, surfaces (DEM's), orthophotos, points, profiles).
human activities such as deforestation or excavation of slopes Photogrammetry is an important contribution to many
for road cuts and building sites, etc., have become important disciplines. Landslide studies can be effectively done using
triggers for landslide occurrence (Dai et al., 2002). aerial photographs with photogrammetric tecniques (Kraus,
1993)
Monitoring landslide activity is of paramount importance for
landslide studies. In the landslide studies, remote sensing The importance of mapping, quantifying, and monitoring
imagery is a very powerful tool for landslide monitoring changes in the physical characteristics of landslide area has
because it offers a synoptic view of the landslide that can be been determined in the study. Furthermore, changes in selected
repeated at different time intervals. Landslide monitoring is to an landslide area was determined using dijital photogrammetric
light the way for new landslide and retrogressive failure in the techniques. Landslide profiles was exctracted and analyzed by
old landslide. Landslide monitoring is generally accomplished using the aerial images with dated 1996 and 2002 covering
by field-based geodetic, geotechnical and geophysical landslide area. The areas affected by landslide was determined
techniques complemented with aerial photo interpretation by examining the formation of the changes.
(Mikkelsen, 1996; Keaton and DeGraff, 1996). Most field
techniques, however, only provide point-based measurements
of the landslides. In addition, they do not give information on
past movement episodes. Although ground-based techniques are
necessary to acquire very precise information on displacement
* Corresponding author.
736
Interne
The s
meridi:
part in
Accordi
the cold
°C, the |
RC. Riz
more th
symmet
shift the
thereby
landslide
rainfall.
speed of
has bee
landslide
yearly ir
results ir
Tea gar
and tea |
the roots
surface |
materials
saturated
Thus, m
acidic r
weatherii
situation
