Detection of the Great Wall using SIR-C data in North-Western China

A segment of ancient Chinese Great Wall was imaged by Shuttle Imaging Radar-C. The wall is situated in the desert region and even partly buried in a thin sand layer. SIR-C image reveals the whole segment of the wall. There are three walls imaged by SIR-C. Two were built in Ming Dynasty (1474 A.D. and 1531 A.D.) and one was built in Sui Dynasty (585 A.D.). The Great Wall in Ningxia and Shanxi Province was made of loess soil taken from the local wind-blow sedimentary deposits. The wall is seriously damaged by erosion. This paper presents a study of the radar imaging mechanism of the Great Wall, radar backscatter from the wall in relation to the frequency and polarization. The study shows that the long wavelength L-band radar image is better for detection the wall, especially in sand covered areas. Multi-frequency, multi-polarization SAR image is an effective tool for detecting the special historic remains, such as the Silk road, ancient graves etc