Detection of Buffer Changes of Historical Monuments ...

3rd EARSeL Workshop on Remote Sensing for Archaeology and Cultural Heritage Management Ghent, Belgium, 19st – 22nd September, 2012

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Detection of Buffer Changes of Historical Monuments and Sites Using Remote Sensing Methods Case Study: Great Wall of Gorgan Abbass Malian1, Seyyed Ahmad Hosseini Fathabad 1. Shahid Rajaee Teacher Training University, Tehran, Iran; [email protected]

ABSTRACT Buffer of ancient monuments is studied form three point of view: Conservation buffer, Landscape buffer and Functional Buffer. In conservation buffer, change in usage and construction in the surrounding area of the monument is controlled. In landscape buffer, the environmental condition and the view seen by the observer is considered. In functional buffer, the appropriate application of the monument and its related area is studied. The Great Wall of Gorgan is an ancient wall constructed more than two thousand years ago form the top of Elburz mountains in Gomishan to the beach of Caspian sea in Kalaleh. The main purpose for building such huge wall was the prevent tribes living in North-East territories from invasion to the interior part of Persia. This is the second great historical-defensive wall in the world. The Iranian Cultural Heritage Organization has decided to conduct necessary operations and research work in order to prepare the file for the nomination of this monument in the World Heritage List of UNESCO. Essential documentation and implementation of the buffer area of the monument are of importance for this purpose. This research is a major step toward this international program. In the current research, buffer area of the Great Wall of Gorgan is precisely detected based on the analysis of aerial and satellite images and fusion of these data with other spatial information such as old photos, historic maps and attributes gathered form disciplines like archaeological researches, architectural studies, etc. and then implemented on a base map. Then, the change process of that buffer with respect to time is modeled. Different processes such as radiometric, principal component transformation and classification are used, compared and analyzed in this research. The management of the cultural heritage will be able to make the best decision for the conservation of this monument based on the spatial information provided by this research. KEYWORDS: Cultural Heritage, Archaeology, Documentation, Buffer Zone, Data Fusion, Image Classification, Change Detection

Remote

Sensing,

INTRODUCTION Iran has always been invaded by foreign countries since ancient times. Therefore, the existence of special defensive fortifications in the critical points was important to governments, states and even people. These defensive fortifications were built in the form of walls, towers and ramparts, moats, gates, castles and citadels.

3rd EARSeL Workshop on Remote Sensing for Archaeology and Cultural Heritage Management Ghent, Belgium, 19st – 22nd September, 2012

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THE GREAT WALL OF GORGAN Gorgan was strategically important in the late Ashkanids and early Sassanids period: It was an important military region protecting against Central Asia nomads. So, the Persian kings built an awesome and sophisticated barrier called the Great Wall of Gorgan (or the Red Snake which owes its name to the red color bricks) against these tribes attacks. "A wall against the enemies of God" is even mentioned in the Holy Qur'an (18, 94-97); it remains disputed, however, whether this passage refers to this or to a different border wall. This imperial frontier was made in 5th century A.D. with about 200 km length and with 30 associated forts. The Wall width varies from 10 m to 30 m and its height range is 2 m to 5 m.

Figure 1: Map of Gorgan Wall with its over 30 associated forts, running from south-east shore of the Caspian Sea into Elburz mountains (Source: Kiani, 1982)

The Great Wall of Gorgan starts at Kalaleh, eastern beach of the Caspian Sea, and passes north of Aq-Gala and Gomishan, north of Gonbad and then stretches north-eastward in Elburz mountains and finally fades amongst Pish-Kamar mountains on the Bojnourd slopes. Alongside the Gorgan Wall a major irrigation canal or moat with 2 m depth was dug, supplied by a reservoir behind a 900 m long and 20 m high dam in the Gorgan river valley.

3rd EARSeL Workshop on Remote Sensing for Archaeology and Cultural Heritage Management Ghent, Belgium, 19st – 22nd September, 2012

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Figure 2: Gorgan Wall and water ditch Figure 3: Sassanid historical dam (Source: Arman Ershadi)

The exact origin of this huge monument is ambiguous, but according to historical facts, it can be certainly related to the major emperor of the Ashkanid dynasty: Mehrdad, the Second (123-87 BC). It was rehabilitated during the Sassanid dynasty, particularly in the period of great Persian king Khosrow, the First, Anushirvan (531-579 AD). The Great Wall of Gorgan is the longest wall in the world after the Great Wall of China and is considered as the longest brick wall in the world. .

Figure 4: Extent of Gorgan Wall in north-east Iran (Source: Google Earth, 2012/18/09)

The Iranian Cultural Heritage Organization has decided to conduct necessary operations and research work in order to study and protect the Great Wall of Gorgan and to prepare the file for the nomination of this important monument in the World Heritage List of UNESCO. Essential documentation and implementation of the buffer area of the monument are of importance for this purpose. This research is a major step toward this international program.

3rd EARSeL Workshop on Remote Sensing for Archaeology and Cultural Heritage Management Ghent, Belgium, 19st – 22nd September, 2012

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In the current research, buffer area of the Great Wall of Gorgan is precisely detected based on the analysis of aerial and satellite images and fusion of these data with other spatial information such as old photos, historic maps and attributes gathered form disciplines like archaeological researches, architectural studies, etc. and then implemented on a base map. Then, the change process of that buffer with respect to time is modeled. Different processes such as radiometric, principal component transformation and classification are used, compared and analyzed in this research. The management of the cultural heritage will be able to make the best decision for the conservation of this monument based on the spatial information provided by this research.

Figure 5: Corona reconnaissance image showing the Great Wall and its associating structures (Source : Rekavandi, 2008)

PREVIOUS WORKS There is little information about the architecture and archaeology of the sites in this region. No documentation of the whole monument is available for research or protection purpose.

3rd EARSeL Workshop on Remote Sensing for Archaeology and Cultural Heritage Management Ghent, Belgium, 19st – 22nd September, 2012

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Figure 6: USA military map of the USSR-Iran border compiled in 1951 illustrating the route of the Great Wall of Gorgan (Source: N.G.O.)

In the early 20th century, when the area was first mapped, much of the region has been described as the camp grounds of Turkmen nomads.

Figure 7: Photomosaic of the region of the Great Wall of Gorgan (Source: N.G.O.)

3rd EARSeL Workshop on Remote Sensing for Archaeology and Cultural Heritage Management Ghent, Belgium, 19st – 22nd September, 2012

Figure 8: High oblique aerial photo of the Great Wall of Gorgan (Source: George Gerster)

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3rd EARSeL Workshop on Remote Sensing for Archaeology and Cultural Heritage Management Ghent, Belgium, 19st – 22nd September, 2012

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Erich F. Schmidt made the first aerial survey of the monument in 1945. The most extensive previous fieldwork project on the Gorgan Wall, including the compilation of detailed maps, was carried out in the 1970s by M.Y. Kiani.

Figure 9: Archaeological excavation for investigating the Great Wall of Gorgan (Source: Arman Ershadi)

Nokande et. al. (2006) conducted a joint fieldwork project, between the Iranian Cultural Heritage Organization of Golestan Province and the University of Edinburgh in 2005 to test to what extent modern archaeological techniques, notably geophysical survey, landscape survey, radiocarbon and optically stimulated luminescence dating, had the potential to shed light on the architecture, function and date of the important, yet enigmatic, Gorgan Wall. In that project, the goal was revealing the interior layout and architecture of the monument, clarifying hydraulic features associated with the Great Wall of Gorgan and investigating other characteristics related to it. Other works concerning historical, archaeological and architectural aspects of the Great Wall of Gorgan which are beyond the scope of this paper can be found in the related literature.

3rd EARSeL Workshop on Remote Sensing for Archaeology and Cultural Heritage Management Ghent, Belgium, 19st – 22nd September, 2012

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Figure 10: Plan of one of the trenches of the Great Wall of Gorgan; GPS measurement was made to locate the corners of the trenches Figure 11: Magnetometer surveying for detection and analyzing of the Great Wall forts (Source: Nokande, 2006)

RESEARCH METHODOLOGY To conduct the change detection process for determination type and amount of violations to the Great Wall of Gorgan and its neighboring zones that have occurred in recent decades, two temporal epochs were selected. The first epoch is about 1960 (OLD data set) and the second one is about 2010 (NEW data set) providing the sufficient temporal interval about half a century for the required processing.

DATA SOURCES The main source of data for this research was the IRS satellite images. The Indian Remote Sensing Satellite (IRS-P5) or CARTOSAT-1 built by ISRO (Indian Space Research Organization) has an improved sensor system that provides 2.5 m resolution. It is a stereoscopic Earth observation satellite in a sun-synchronous orbit. Its mission caters to the needs of cartographers and terrain modeling applications. The satellite will provide cadastral level information up to 1:5000 scale and will be useful for making 2-5 m contour maps. These images can be received and processed by Sepehr satellite receiver belonging to the National Geographical Organization (NGO) of the Armed Forces of Iran.

3rd EARSeL Workshop on Remote Sensing for Archaeology and Cultural Heritage Management Ghent, Belgium, 19st – 22nd September, 2012

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Figure 12: CartoSat-1 satellite (IRS-P5) Figure 13: Sepehr satellite data receiver of N.G.O. (Iran)

Figure 14: A scene of panchromatic satellite image captured by CartoSat-1 showing the extent of the Great Wall of Gorgan and its surrounding area

3rd EARSeL Workshop on Remote Sensing for Archaeology and Cultural Heritage Management Ghent, Belgium, 19st – 22nd September, 2012

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Table 1: CartoSat-1 (IRS-P5) Satellite imagery specifications (Source: ISRO) Sensor Mode

Reference Datum

Platform Weight

Platform Height

Launch Date

Capture Date

Revisit Cycle

Spatial Resolution

Orbits per Day

Image Swath

PAN

WGS84

1560 kg

618 km

2005

2008

5 days

2.5 m

15

30 km

Besides the above-mentioned satellite images, old and new aerial photos and topographic maps of the region were also collected so that change detection operation could be applied.

Figure 15: Different topographic maps of the monument region corresponding to the desired epochs

Figure 16: Sample corresponding magnified map zones

Figure 17: Parts of aerial and satellite images of the region corresponding to the desired epochs

3rd EARSeL Workshop on Remote Sensing for Archaeology and Cultural Heritage Management Ghent, Belgium, 19st – 22nd September, 2012

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CHANGE DETECTION Change detection is one the main applications of remote sensing. There exist different methods for Data Fusion and change detection among which Principal Component Analysis (PCA) and Hybrid Classification are very useful and easy to implement. The mathematical detail of these techniques can be found in remote sensing and image processing texts.

Figure 18: Result of co-registration and fusion of the NEW epoch data

3rd EARSeL Workshop on Remote Sensing for Archaeology and Cultural Heritage Management Ghent, Belgium, 19st – 22nd September, 2012

Figure 19: Result of co-registration and fusion of the OLD epoch data

Table 2: Flowchart of the work

Step 1

•Site Seletion & Data Collection

Step 2

•Identification & Interpretation

Step 3

•Co-Registration & Data Fusion

Step 4

•Classification & Detection

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3rd EARSeL Workshop on Remote Sensing for Archaeology and Cultural Heritage Management Ghent, Belgium, 19st – 22nd September, 2012

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Figure 20: Resulting change detection map of the Great Wall of Gorgan

CONCLUSION It becomes evident from the results of this research that the protection conditions of this valuable monument is disastrous and its buffer zone including conservation, functional and landscape zones has been violated. The produced Change Detection Map depicts that the Great Wall of Gorgan has been badly damaged in recent decades due to human interventions, illegal excavations, industrial activities, engineering projects, plowing farmlands and construction works in its buffer zone and has undergone irreparable destructions in many aspects of it. Due to rapid modernization and sub-urban development and its dangerous consequences, an immediate action to stop violations and for recovery and protection of this ancient monument is of great necessity and importance. Local, national and international institutes must pay attention to prevent further damage of the Great Wall of Gorgan. To do so, fundamental study of the monument should be followed for which a precise geometric recording of its current status and neighboring zones is a prerequisite. Concerning this subject, the first author has the experience of cooperating within Recording, Documentation and Information Management (RecorDIM) initiative. The premise behind the RecorDIM project—organized by the Getty Conservation Institute—was to improve conservation practice by improving the ability of professionals to gather, create, manage, and interpret documentation. Drawings, images, surveys, and historic research of a

3rd EARSeL Workshop on Remote Sensing for Archaeology and Cultural Heritage Management Ghent, Belgium, 19st – 22nd September, 2012

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structure or archaeological site are essential for good conservation planning and are known in the field as methods of documentation. Important conservation decisions could then be made with better and more accessible information.

Table 3: Framework of RecorDIM initiative (Source: Getty Conservation Institute)

FUTURE WORK AND SUGGESTIONS The first step towards an in-depth analysis of an ancient monument or site is a thorough and detailed documentation so as to perform correct identification, interpretation and understanding of the monument. It is quite necessary that the Great Wall of Gorgan and its surrounding area be completely documented by means of geomatic techniques such as close range photogrammetry and surveying, remote sensing, global positioning system, hydrography and so on. Moreover, multispectral analysis for environmental research and detection pollutions of the area is needed. The resulting documents should be integrated into a geospatial information system (GIS) for further study and investigation as well as for management and protection purpose. With the support and collaboration of the Iranian Cultural Heritage Organization, the first author is trying to carry out such documentation project according to the guidelines of the International Committee for Heritage Documentation (CIPA) to which he has been the national delegate of Iran.

3rd EARSeL Workshop on Remote Sensing for Archaeology and Cultural Heritage Management Ghent, Belgium, 19st – 22nd September, 2012

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ACKNOWLEDGEMENT The authors are thankful to Mr. Hamid Omrani Rekavandi, head of the Cultural Heritage Base of the Great Wall of Gorgan for his support and providing some related data. General Dr. Mohammad Hassan Nami, head of the National Geographical Organization (NGO) of the Armed Forces of Iran, is greatly acknowledged for providing the authors with IRS satellite images and old aerial photos and topographic maps of the region of study. REFERENCES

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E. Sauer, Rome's Neighbors: The Reality, Art History and Power, 2007. Kiani, M.Y., Parthian Sites in Hyrcania, The Gurgan Plain, Archaologische Mitteilungen aus Iran Erganzungsband 9, Berlin, 1982. Barshan, S. H., The Use of Mud-Brick in the Defensive Wall of Gorgan, Earthen Architecture in Iran and Central Asia, London, 2005. Nokandeh, J., et al., Linear Barriers of Northern Iran: The Great Wall of Gorgan and the Wall of Tammishe, Journal of Persian Studies, London, 2006. Rekavandi, H. O., et al., Secret of the Red Snake, Current Archaeology, No. 27, 2008. Malian, A. (Project Manager), Integrated Documentation, Three-Dimensional Reconstruction and Digital Modeling of Ghabus Tower in Gonbad Kavus using Close-Range Photogrammetry and Surveying for World Heritage Registry, Technical Report, Cultural Heritage Base of the Great Wall of Gorgan, Gorgan, 2008. Malian, A. and Zolfaghari, M., Non-Metric Cameras in Architectural Photogrammetry, Vol. B5, XIX International Congress of Photogrammetry and Remote Sensing (ISPRS), Amsterdam, The Netherlands, 2000. Malian, A. and Zolfaghari, M., Documentation of the Ancient Village of Kharanagh for Rehabilitation Purpose: A Preliminary Report, XX Symposium of the International Committee for Heritage Documentation (CIPA): International Cooperation to Save the World's Cultural Heritage, Torino, Italy, 2005. Zolfaghari, M and Malian, A., Documentation of the Documentations of the King of the Kings, International Congress of Photogrammetry and Remote Sensing (ISPRS), Istanbul, Turkey, 2004. Rekavandi, H. O., et al., Sasanian Frontier Wall in Northern Iran, 6th International Conference on the Archaeology of the Ancient Near East, Rome, 2008. J.S. Deng, et. al., PCA-Based Land-Use Change Detection and Analysis using Multi-Temporal and Multi-Sensor Satellite Data, International Journal of Remote Sensing, Vol. 29, 2008. D. Lu, et. al., Change Detection Techniques, International Journal of Remote Sensing, Vol. 25, 2004. G. Simone, et. al., Image Fusion Techniques for Remote Sensing Applications, Technical Report, University of Trento, 2002. D. E. Bar, et al., Target Detection and Verification via Airborne Hyperspectral and High Resolution Imagery Processing and Fusion, IEEE Sensors Journal, Vol. 10, 2010. T. Lillesand, et al., Remote Sensing and Image Interpretation, 2007.