Download Use of satellite data for tectonic interpretation, nw Himalaya

C O V E R ARTICLE
Photonirvachak
Journal of the Indian Society of Remote Sensing, Vol. 32, No. 3, 2004
USE OF SATELLITE DATA FOR TECTONIC
INTERPRETATION, NW HIMALAYA
CHIRASHREE MOHANTY, DIBYA J. BARAL* AND JAVED N. MALIK
Department of Civil Engineering,
Indian Institute of Technology, Kanpur-208 016, India
Mountain topography is the result of highly
scale-dependent interactions involving climatic,
tectonic and surface processes. Tectonic
geomorphology deals with the geodynamics and
geomorphic manifestation of crustal deformation
processes. In Himalaya, bulk of the relief in
mountainous region has been formed by uplift along
thrust faults striking sub-parallel to the trace of the
thrust zones. Therefore, there is an intimate link
between uplift rates, material redistribution rates due
to geomorphic processes, and the morphology of
the area. By quantifying features the tectonic uplift
rates and constrains geomorphic process rates can
be inferred. To understand the complex interrelationship of these elements in regional scale,
there is a need to develop new approaches and
methodologies. With significant improvement in
resolution of available digital terrain data and
computing resources, the evaluation of
morphotectonic in a Geographical Information
System (GIS) environment tends to be quantitative
and more precise.
The evidence of neotectonic activities are
commonly available through various geomorphic
*Corresponding author : [email protected]
Received 20 June, 2004; in final form 28 July, 2004
signatures that can be studied using geological
(such as lithology, proximity to active faults and
lineament density) and geomorphological aspects
(such as landform, slope, lateral erosion by streams,
drainage texture, spring sapping, elevation difference
between adjacent valleys, altitude and relief).
Numerous studies have been made to develop
such relationship between the tectonics and
morphology in the Himalaya and various other
tectonic zones by conventional field methods e.g.
river terrace study in river bank cross section,
drilling, trenching, seismic profiling, and
sedimentological studies, radiometric dating etc.
(Thakur, 1995; Burbank, 1999; Philip and Sah, 1999;
Malik et al., 2003). But these are expensive, time
consuming and only represent point and linear scale
features in regional context. Analysis of DEM
(Digital Elevation Model) in conjunction with remote
sensing satellite data by numerical geomorphology
provides a means for characterizing tectonic activity
of an area in a quantitative way. Using digital terrain
data in the form of DEM (Digital Elevation Model),
and software tools have made the study easy and
accessible everywhere. Under the frame work of GIS,
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Chirashree Mohanty et al.
analysis of geospatial data to derive interrelationship becomes increasingly important.
An approach to study the regional variations
in tectonic geomorphology along a segmented
convergent plate boundary has been developed by
Wells et al. (1988). Geomorphic observations of
rivers in costal cordillera of northern Chile taking
certain geomorphic parameters have been carried
out by Riquelme et al. (2003). Another approach of
studying the rate of upliftment taking the
morphotectonic properties of the Lo River Fault near
Tam Dao in North Vietnam was carried out by
Cuong and Zuchiewicz (2001).
The study area within latitude 31~176 and
longitude 76~176 is covered by the Survey of India
Toposheet 53A in 250,000 scale and comprise of 9
districts of Punjab and Himachal Pradesh (Fig. 1).
Physiographically, the study area consists of three
major divisions the Siwaliks, Lesser Himalaya, and
Higher Himalaya separated by the major thrust zones
namely the Himalayan Frontal Fault, the Main
Boundary Thrust and the Main Central Thrust,
respectively. In the present study, analysis of the
Himalayan terrain has been made using a Digital
Elevation Model (DEM) and satellite data to
evaluate different zones of active upliftment. Northwestern Himalaya presents a structurally complex
Fig. 1. Lineaments Mapped from Landsat TM over Study Area and Lineament Rose Diagram
Use of Satellite Data for Tectonic Interpretation...
landscape around the Kangra recess and the area
west covering the Beas and Satluj valley. The
structural in-homogeneities of NW Himalayan
Mountain belt between reentrant and the frontal
thrust provide the opportunity to study morphology
and tectonics in an active compressional
environment. Analyses have been carried out to
highlight the variations of morphotectonic features
and to illustrate the relative activities in different
tectonic regimes for the study area.
Shuttle Radar Topographic Mission (SRTM)
provided the elevation data needed to create a
seamless DEM of 80% the world's landmass at
different spatial resolution through the use of
243
synthetic aperture radar (SAR) technology.
Extensive DEM data from a single source as with
SRTM is especially desirable because it is consistent
and comparable across large areas, compared to
other high resolution DEMs derived from variable
sources like individual satellite images. The SRTM
data used for the present study area is having
resolution 90 m and is able to provide greater
variability of 1:50,000 scale map. For terrain cover
data, Landsat TM, and IRS-ID LISS-III data in
different spectral bands having resolution 28.5 and
23.5 m respectively have been used. Satellite terrain
data can be draped over the digital terrain models
that help to visualize and provide structural features
in 3D perspective views (Fig. 2).
Fig. 2. 3D Perspective View from Landsat TM True Color Composite Image Draped Over DEM
244
Chirashree Mohanty et al.
The influence of subsurface structural features
on channel patterns and the overall architecture of
the watershed basins were studied. Regional
analysis of drainage basin and river valley
morphology helps to define differential uplift in
many tectonically active regions. Linking of the
geomorphological parameters with the hydrological
characteristics of the basins provide a simple way
to understand the tectonic behavior of different
contiguous basins. The elevation models help
calculation of hydrologic parameters (stream order,
density, gradient, etc.) in a GIS database quickly
which otherwise take years to calculate manually.
Hypsometry or the frequency distribution of
elevation is often used in geomorphic analysis of
form and process of a landscape. The hypsometric
integral (HI) provides a means of quantifying a
proportion of total drainage basin elevation relative
to that of the total drainage basin area. The
hypsometric curve and HI (integral of these curves)
value obtained for an individual drainage basin are
normalized quantities and therefore allow
comparison of one basin to another, regardless of
size. Recent studies have demonstrated the utility
of hypsometric analysis in tectonic interpretation.
High HI values have generally been associated with
higher rates of tectonic activity and linear range
fi-onts (McNamara et al., 1999).
Convex hypsometric curves with high value
hypsometric integral reflect watershed basin with an
important proportion of their surface located at high
altitudes, i.e. incised watershed basin, whereas
concave curves basin with an important proportion
of their surface located at low altitudes. Large
incision can be attributed to uplift of the area.
Drainage Density: Drainage density is the ratio
of the total length of all channels in a given basin
to the drainage area of the same basin. This number
describes how densely a basin is channelized and
in turn represents amount of tectonic uplift compared
to stream down cutting (Jianjun et aI., 1998). Stream
Length (SL) Gradient Index. The stream length
gradient index is the rate of change of slope along
stream and correlates to stream power. Stream
gradients of trunk channels provide a quantitative
measure of tectonic activity or quiescence. High
stream gradients are indicative of high rates of
tectonic uplift. Lineament Density. Lineaments are
mappable linear surface features which differ
distinctly from the patterns of adjacent features and
presumably reflect subsurface phenomena. The
standard FCC generated from the satellite imagery
is sharpened by edge enhancement filter before
extracting the linear features. Major faults and
lineaments have been mapped by visual
interpretation based on lithological dislocation,
joints and fracture traces, truncation of outcrop,
alignment of streams, sudden bending of streams
(Figs 1, 5a).
For the study area the SRTM DEM (90 m) has
been processed to delineate flow grid and channel
links from automated drainage extraction processes
as shown in the flow chart (Fig. 3). Various imageprocessing software / techniques have been
employed to enhance the data in order to assist in
the delineation of river basin boundaries, calculation
of point attributes and interpolation for getting
regional distribution in the map (Fig. 4).
Extracted drainage has been rasterized, gridded
for 1 km pixels for stream length gradient index and
drainage length density (Figs. 5b, d). To study the
variations of intra and inter-river system tectonicgeomorphic analyses, basins of fourth order streams
for major drainages were delineated. Area Elevation
curve for each basin and HI for each basin is
calculated and assigned to the central point. To map
the distribution of each parameter over the study
area, a moving average interpolation method was
used (Fig. 5c). The Moving average operation is a
point interpolation which values for the output
pixels are the weighted averages of input point
hypsometric integral values within radius of
influence.
Use of Satellite Data for Tectonic Interpretation...
245
Fig. 3. Flow Chart for Drainage Network Extraction and Analysis
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E l e v a t i o n Data
SRTM
Drainage
Network ]-.~
RS T e r r a i n Data
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Slope, A s p e c t , F l o w Grid
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Lineaments 1
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Drainage Density map
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.............
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Hypsometric Integral
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Lineament Density Map
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Litholoclical / Structural M a p
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Fig. 4. Thematic Maps Derived from Satellite Data for Analysis
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246
Chirashree Mohanty et al.
Fig. 5. Interpolated maps for (a) Lineament Density, (b) SL Gradient Index,
(c) Hypsometric Integral and (d) Drainage Density
Each output interpolated thematic raster map
was compared with the vector structural and
lithological map of the area in a GIS environment.
These relationships can be further used for the
development of a suitable algorithm to be used a
GIS environment. The zones pertaining to different
tectonic activity in the study domain have been
identified.
An attempt has been made to study the different
morphometric parameters such as drainage and
lineament density and hypsometric integral, which
are consistent with an interpretation of the
differential uplift within the area. Thematic maps
produced for each of the parameters are analyzed
discerning relationship of each layer to tectonic
framework of the study area along NW Himalaya.
Use of Satellite Data for Tectonic Interpretation...
In the present study, three major divisions of
the different landform settings were analyzed with
a focus on the response of the fluvial systems to
discrete tectonic perturbations. An attempt has been
made to relate stream power, drainage density and
hypsometric integral to explain the amount o f
erosion and behavior o f structurally controlled
mountain front with that of the tectonic uplift of the
regions.
Utility of DEM and remote sensing data for
regional scale tectonic studies has been shown.
With the help of digital terrain data, important
morphometric parameters are mapped and studied.
Both the statistical and spatial variability of different
parameters within the region and among the regions
were investigated in detail and found to be in
agreement with the existing structural models.
Thematic maps indicative o f tectonic
morphologies are prepared and have been used into
the spatial database for further GIS analysis. The
quantitative relations for combining the thematic
maps for deriving the final activity zonation map for
the study area are being worked out. This should
enable us to collate the morphometric parameters in
quantitatively to calculate the Tectonic Zonation
Map. This map can be used in cross disciplinary
study o f Landslide Hazard, Earthquake, and
Geotechnical studies in t e c t o n i c a l l y active
Himalayan belt.
Acknowledgements
This work is a part of M. Tech dissertation of
CM; DJB is thankful to TATA STEEL, Jamshedpur
for partial financial grant. Financial support through
research project (SR/FTP/ES-46/2001) sponsored
by the Department of Science and Technology, New
Delhi to JNM is duly acknowledged. Authors would
like to thank Dr. R. P. Singh, Chief Editor for
providing valuable suggestion to improve the
original version of manuscript.
247
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