Performance of GPR attribute analysis to detect and characterise buried archaeological targets near Ukhaidir palace, Iraq

Ukhaidir palace is an outstanding example of Mesopotamian architecture and of great interest to many researchers and archaeologists. However, the builder of this palace and the time of construction remain controversial. During recent decades, several archaeological sites and cultural heritage around it have vanished as a result of neglect, degradation, and man-made interventions. A ground penetrating radar (GPR) survey was conducted at two sites (A and B) near the palace: site A is located in front of the palace a few metres away, while site B is located about 155 m NE of the palace. 2D and 3D GPR attribute analysis were used, including the instantaneous phase, root-mean-square (RMS) amplitude, as well as sweetness attributes to improve the interpretation and achieve the best results. The results led to identifying a number of anomalies: seven of them were interpreted to be ancient walls, while the others were associated with a karez (water canal) and an external wall. RMS amplitude and sweetness attributes successfully determined the boundaries and the horizontal continuity of the ancient walls, but the RMS amplitude was more accurate. The instantaneous phase detected the highly contrasting features of the buried structures but failed to specify the targets having an angle equal or close to the soil phase angle.