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PRODUCING LANDSLIDE RISK MAP OF SEBINKARAHISAR
BY MEANS OF REMOTE SENSING AND GIS TECHNIQUES
D. Z. Seker^ *, M. O. Altan?, Z. Duran? , M. B. Shrestha?, A. Yuasa?, K. Kawamura
* ITU, Civil Engineering Faculty, 34469 Maslak Istanbul, Turkey - (seker, oaltan, duranza)@itu.edu.tr
River Basin research Center Gifu University, 1-1 Yanagido, Gifu city 501-1193, Japan — (yuasa,madhu@green.gifu-u.ac.jp)
KEY WORDS: GIS, Landslide, Remote Sensing, Hazards, DEM/DTM
ABSTRACT:
The objective of this study is to determine a suitable methodology for predicting possible landslide areas and producing landslide
risk map in the study area of Sebinkarahisar Township, which is located at the northeastern part of Turkey. In the study, various
types of data were used to extract relevant information. These include the satellite sensor data taken in the year of 1987 and 2000,
which are used for the extraction of land surface temperature and land use information. 1:25000 scale standard topographic map has
been digitized and the obtained contours were used for the derivation of Digital Elevation Model (DEM) and slope map of the study
site. Satellite images, DEM and slope map of the study area were used to investigate the possible landslide risk areas and reasons of
this natural hazard which threat the study area frequently.
1. INTRODUCTION
Landslide is a slide of a large mass of dirt and rock down a
mountain or cliff. Landslides have become one of the world's
major natural disasters in the recent years in many countries.
Prediction of potential landslide areas has been very difficult
because of the complexity of the factors involved and the
relationship to each other, which is wide ranging. The factors
that arc usually related to landslides are geology, soil type, land
surface temperature, land cover, underground water level, slope
aspect, slope inclination, elevation, etc. Normally, the causes of
landslide are determined by carrying out sampling of the soil,
rock, slope inclination, land cover, underground water level,
geology, etc. at the site. It is a difficult and time consuming job
to do this for a large area from time to time and by integrating it
with GIS, all the information can be combined, manipulated and
analyzed to determine potential landslide areas.
The integration of GIS with remote sensing data and thematic
map may highly facilitate the assessment and estimation of
regional landslide hazards (Yuan and Mohd, 1997). In this
study, land surface temperature and land use information have
been obtained from Landsat TM data taken in the 24 September
1987 and 17 July 2000. The elevation and slope inclination of
the study area have been determined from DEM generated
using contours digitized from 1:25000 scaled standard
topographic map.
Researchers to predict landslide potential areas usually use the
land surface temperature, which is closely related to
underground water level. Land surface temperature is calculated
using satellite sensor data. This process is done because
according to previous researches, most landslide areas have
temperature between 24-26 °C. According to previous
researches, most of the landslides occur at slope inclination of
35° - 45°. The slope inclination map was generated from the
DEM. Both the DEM and slope inclination maps were used to
produce landslide risk map (Yuan and Mohd, 1997, Shikada,
1994),
Corresponding author
465
All the data were manipulated and processed by using the
ArcView and Erdas Imagine software. Several different risk
map related to landslides in the study area were evaluated by
different research groups and government institutions. In the
different landslide maps obtained from previous studies, were
classified into different risk zones. The most risky areas are
classified. Remote sensing has been used to study characteristic
properties of ground surface due to the advantages of its broad
area observation and periodicity.
The integration of GIS with remote sensing data and thematic
map data may facilitate greatly the assessment and estimation
of regional landslide hazards. In the study, land surface
temperature and land use information have been derived from
Landsat TM data. The elevation and slope inclination have been
determined from DEMs generated from standard topographic
maps. Reliable data related to underground water level could
not be obtained. Using all relevant data, simple algorithms were
used and by combining all the risk maps using GIS techniques,
final risk maps were produced which take into account all of the
factors.
An integrated approach of remote sensing and GIS is highly
useful in evaluation, management and monitoring of natural
hazards. Routine use of remote sensing data and its analysis of a
hazard prone area help to monitor the changes in surface
feature. The digital image processing techniques enable the user
to get the desired information in a more reliable, quicker and
easier way. The goal of this study is to generate a landslide
zonation map using GIS and remote sensing based methods.
Use of satellite imagery has been incorporated in mapping the
lineaments as a result of which are projected to better
characterize the landslides of the study area. The landslide risk
assessment has been studied in detail within the last 30 years.
Various attitudes to a solution of this task have brought a large
range of possible solution methods. They can be divided into
five big groups. These groups are given in Table 1 (Halounova
and Pavelka, 1998).