Radar Imaging and Its Application to Archaeology

L Kemp

This presentation will examine the utility of remote sensing to the distribution of archaeological sites within a region. It will do this by evaluating the following:

• A review of testing and evaluation of Airborne Synthetic Aperture Radar to image geologic features and structures in arid and semi-arid environments

• The potential of AirSAR to test for archaeological features within arid and semi-arid regions

NASA shuttle Imaging Radar mission (SIR-A, SIR-B, and SIR-C) demonstrates the capability of radar to image subsurface geologic formations up to 2 m in arid and semi-arid environments.

SIR-C image of the Nile River, Sudan.

SIR-C Color Composite (Jensen)

The Airborne Synthetic Aperture Radar (AIRSAR) was designed, built, and is managed by the Jet Propulsion Laboratory (JPL). AIRSAR is a side-looking radar instrument and can collect fully polarimetric data (POLSAR) at three radar wavelengths: C-band (0.057 m), L-band (0.25 m), and P-band (0.68 m). AIRSAR serves as a NASA’s research vehicle for demonstrating new radar technology and data acquisition for the development of radar processing  techniques and applications. As part of NASA’s Earth Science Enterprise, AIRSAR first flew in 1988 and continues to conduct at least one flight campaign each year, either in the United States or on an international mission. (http://airsar.jpl.nasa.gov.)

• “The Importance of SAR Wavelength in Penetrating Blow Sand in Northern Arizona” in Remote Sensing of the Environment 69(1999) Gerald G. Schaber and Carol S. Breed

• “SAR studies in the Yuma Desert, Arizona: Sand Penetration, Geology, and the Detection of Military Ordnance Debris” in Remote Sensing of the Environment 67(1999) Gerald Schaber

These articles focus on

• The use of C-, L-, and P-bands to discriminate geologic features

• Data collection in the four transmit-receive polarization modes (HH, VV, HV, VH)

Topographic map of Ward Terrace study area with AirSAR and ERS footprints

• The “sand streak” is 7 km long, and .5 km wide with a max. depth of 2.5 m.; it extends northeast across the terrace where it supplies sand to a dune at the base of the Moenkopi Plateau. Based upon laboratory analysis the sand streak consists of well sorted and unimodal quartz sand with an overall soil moisture of 2.2%.

ERS-1 image of Ward Terrace taken 22 June 1992, Band-C, VV

U-2 photograph of Ward Terrace at 20,000 meters altitude

Band-C, HH Band-C, HV

Band-L, HH Band-L, HV

Band-P, HH Band-P,HV

Geologic Feature Recognition Level (best to worst; left to right)

Sand Streak CHH, CHV, LHH(VV), LHV, penetrated at P-band

Dendritic channels on CHH, CHV, LHH(VV), PHH NE side of terrace (VV), LHV, PHV

Dendritic channels of PHV, LHV, LHH(VV), both side of sand streak PHH(VV), CHV, CHH(VV)

Flat, lag covered PHV, PHH(VV), LHV,

terrace surface LHH(VV), CHV, CHH(VV)

Area of study- Yuma, Arizona

Band C (HH) Band C (HV)

Band L (HH) Band P (HH)

Image of ordnance in target circle.

Band L (HV)

Band P (HV)

Geologic Feature, Target Recognition Level (best to and Cultural Features worst; left to right)

Sand-mantled alluvium PHH, CHH, LHH, LHV, PHV

Scald surfaces PHH, LHH, CHH, CHV, LHV, PHV

Coarse river gravels CHH, CHV, PHH, LHH, LHV, PHV

Target areas PHV, LHV, PHH, LHH, CHV, CHH

Access roads CHH, CHV, PHH, PHV, LHV, LHH

Fence lines PHV, PHH

• The history of archaeological method is of a discipline which has used sophisticated technologies in the search for and understanding of archaeological sites.

• The detection of archaeological sites using AirSAR– The past use of AirSAR in archaeology– Comer and Bloom Proposal to use AirSAR to

identify archaeological sites and features– Fort Bliss as a potential AirSAR study area for

archaeological testing

Application of AirSAR Technology to Archaeology

Converging ancient trade routes represented by purple lines to the city of Ubar, Saudia Arabia. (Holcomb)

Backscatter image on the right allowed identification of subterranean chamber in the city of Petra, Jordan. (Comer)

Image is of AirSAR flight over San Clemente Island. Band L – 6 km swath

One of the GIS themes for San Clemente Island

Fort Bliss as a potential AirSAR study site for archaeological testing

Advantages of Fort Bliss as a AirSAR Study Area

• Fort Bliss is located in an arid to semi-arid environment

• Since the mid 1970’s, Fort Bliss has been engaged in archaeological management of its cultural resources; it has identified approx 10,000 archaeological sites of a potential 100,000 sites.

Conclusions

• The articles demonstrate the utility of AirSAR as a tool for geologic testing and mapping in sand-blanketed desert environments

• The Yuma Desert study demonstrates the it can be used a tool for detection of military ordnance within this same environment

• The application of AirSAR has potential as a tool for archaeologist to detect and locate features associated with human activities within arid and semi-arid areas