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Archaeological site selection
Asis Bhattacharya and K.
Vinod Kumar
NRSA, Hyderabad
G. S. Narasimhan
Archaeological Survey ofIndia, Hyderabad
The launch of high resolution PAN data onboard IRS-1C has tremendously enhanced the application
capability for many thematic mapping. The application of remote sensing
technology in the field of archaeology is in its infancy in the country and
archaeologists are realising the importance of this tool for their survey. There
is very little published literature in the field of application using this
technology. The present study may interest the researchers to apply this tool
for finding new archaeological sites. The conventional survey involves a
detailed fieldwork wherein the archaeologist has to visit village by village and
find out any new archaeological artefacts from local sources. The use of remote
sensing helps them to narrow down the target area for search through some
geomorphic indicators. The PAN data has a spatial resolution of 5.8 metres with
synoptic coverage of 72x72 km. hence, large areas can be observed with good
spatial resolution. Further, expert knowledge from the field of archaeology can
also be used to deduce the signature of known sites in these satellite images
for searching in the unknown area. An integrated approach using collateral
information along with remote sensing data in GIS environment is ideal for this
type of study.
Study Area
The study area is located 60 km.
west-northwest of Hyderabad city on Hyderabad-Mumbai highway near Kondapur
village in Medak district.
The site was first explored by Henry Cousens
in 1900. It is noted for its Middle Stone Age factory site near the stream. The
tools found here include thick lunates, blades, flakes and tortoise cores.
Interestingly, the late Stone Age (Microliths) blades, cores and geometric
continuity of both the traditions. Some of the Neolithic instruments were found
from the nearby hill slopes. This site was discovered by the archaeologists as a
low lying mound approximately 5 m from the ground level between Kondapur and
Terpol village. The excavation of this site has revealed a fortified township of
the Satavahanas dynasty, founded by Simuka, who at the zenith of their power,
ruled a vast kingdom extending between the seas across the Deccan Plateau.
Methodology and Analysis
This site being known as
archaeologically important and covering a large area, was taken as a reference
to deduce spectral and geomorphic signatures from the satellite data for this
particular terrain. Later, these signatures were correlated with other
information like drainage, topoheight and water bodies to create a
knowledge-based database. This database can be used for other unknown and
unexplored sites. Thus, a rule-based search using weighted index method can be
employed.
The analysis was carried out in the ERDAS imagine image
processing and Arc/Info software in Dec ALPHA work station. The various thematic
layers like geomorphology, water bodies, drainage, road network and slope were
generated. A favourability index model was used to derive the most favourable
zone by using existing information about the known site.
A geomorphological map was prepared from the satellite data to understand the
general physiography of the area. Genetically, the area can be grouped under
arid landforms. The landforms mostly seen are inselbergs, pediments and valley
fills. The inselbergs are seen mostly near Nagapur village, northeast to the
site. The other important landform is the shallow buried pediplain, which has a
bright tone in the image. The weathered zone is very thin in this landform with
bedrock exposed at shallow depth. The shallow buried pediplain grade into deep
brued pediplain, which has a thick soil cover and supports vegetation. The
weathering of granitic inselberg generally occurs along three sets of joints.
They are the weak planes in this hardrock. Along these weak planes, drainages
develop, which follow the joints of this rock.
Because of weathering in
course of time, valley-fill deposits develop along these zones. This is the most
fertile plain in this zone. The intersection of multiple joints results in deep
depression because of the weakness. This develops into small natural water
tanks. Many man-made tanks are also there, developed after constructing bunds
across the streams. Hence, the area as seen in the satellite image has numerous
water tanks. These are the favourable areas for settlements. Most of the
settlements, past or present, are always located near to the water body.
Results and Discussions
It is observed that tha existing
Kondapur site of excavation is located on a low-lying mound (topohigh) near a
large water body within a high valley-fill, which was an ancient drainage
channel. These parameters were given weightage, followed by water body and
valley-fills. Using the known weightages, unknown sites were selected for future
explorations. The database also contains the existing roads and other
infrastructure facilities around this site. This information is of immense help
for an exploration programme. The satellite data also gives an update
information about the urban sprawls and settlement around the sites. These are
useful in conservation work of the archaeologically important sites. The
temporal data can be used to monitor these sprawls and detect any encroachment
into such important sites.
Conclusion
The database can be
updated regularly as and when new sites are discovered. This is also
cost-effective technology since this can be developed in a personal computer
(Laptop) and can be carried out in the field. The total cost of this project
covering 50x50 sq. km. area comes to approximately Rs. 15,000 (data and
processing cost). This work can be carried out in seven days in the lab or in
the field. The data collection when supported by GPS is more accurate and
precise. Thus, it can be summarised that this technology is cost-effective,
timely and accurate. This is an essential tool for the archaeologists for their
exploration programme.
(Based on an article published by the authors in
NNRMS Bulletin, May 1998.)
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