ACCURACY EVALUATION OF DEM DERIVED BY TERRASAR-X DATA IN THE
HIMALAYAN REGION
N. Yamane a *, K. Fujita b , T. Nonaka a , T. Shibayama a , and S. Takagishi a
a PASCO CORPORATION, 2-8-10 Higashiyama, Meguro-ku, Tokyo, Japan
naofumi_yamane@pasco.co.jp
b Graduate School of Environmental Studies, Nagoya University, Nagoya 464-8602, Japan
KEY WORDS: InSAR, Glacier, Elevation, Himalayan, SAR, TerraSAR-X, Monitoring
ABSTRACT:
In the past few years, the Himalayan region has experienced a number of floods from glacial lakes, and the
neighboring areas were severely damaged. Therefore it is important to continue monitoring glaciers or creating
simulation of floods to prevent the damages in those regions. The DEM is very useful for studying these hazardous
problems. In this study, we tried to generate DEM by TerraSAR-X images for conducting InSAR processing and
evaluating the quality of the DEMs by comparing them with SRTM data. DEM generated by TerraSAR-X image
could acquire more detailed surface information of the mountaneous region. The end and side of the moraine were
recognizable with TerraSAR-X DEMs. It is expected that the InSAR DEM would be highly useful for monitoring
purposes in the mountainous regions.
1. INTRODUCTION
During past years, the Himalayan region faced several
floods from glacial lakes, and the neighboring areas
were severely damaged (ICIMOD et al., 2007, J.
Komori 2006., etc). If the floods can be predicted well
in advance, the continuous actions, such as making a
good preventive plan and allocating disaster-prevention
facilities, can be adopted well before occurrence of the
floods. Consequently, it is expected that the extent of
the damage of the populated area or infrastructure can
be greatly controlled. The Digital Elevation Model
(DEM) is widely used for flood prediction and
estimating the affected area and utilized for
environmental monitoring as well. It is possible to
detect the temporal changes of glacial lakes, glaciers
and moraines by comparing two DEMs produced at two
different time intervals.
DEMs produced from optical satellite images have been
commonly used for glacier monitoring. However, the
problem is to obtain cloud free images. Most of the
glacial lake outburst flood (GLOF) occurs in the
monsoon season and therefore, monitoring the glaciers
is very difficult due to bad weather conditions and
presence of dense clouds. Data acquisitions,
irrespective of weather conditions, by the Synthetic
Aperture Radar (SAR) satellites of C, L and X bands
can create DEMs.
On June 2007 TerraSAR-X satellite was successfully
launched and presently providing images for the global
users. The X-band radar is capable of extracting
surface features information better than C-band or L-
band sensors due to the short wavelength. Additionaly
DEMs created from X-band sensor satellite images
were not generated by interferometry till recently.
The purpose of this study was to generate DEMs from
TerraSAR-X images utilizing InSAR and evaluating the
qualitative accuracy by comparing with Shuttle Radar
Topography Mission (SRTM) data.
2. METHODOLOGY
In this study, we made our attempts to cover DEMs
from a pair of TerraSAR-X images obtained by High
resolution SpotLight (HS) and StripMap (SM) modes
images. After generating the DEMs, we also evaluated
the qualitative accuracy of the DEMs while comparing
SRTM data for the entire study area.
Corresponding author. This is useful to know for communication with the appropriate person in cases with more than one
author.
