Thermal Analysis of Evapotranspiration in Cultivated Fields for the Detection of Archaeological Anomalies

Abstract

Archaeological aerial thermography has traditionally focused on bare ground terrain; however, recent developments in drone technology have prompted a reconsideration of thermal analysis on cultivated fields. This study investigates three different sites using drones equipped with thermal, RGB and multispectral sensors to identify archaeological anomalies. This research challenges the traditional focus of thermal cameras on vegetation-free terrains by investigating cultivated land, where the perceived temperature is influenced by evapotranspiration—a combination of soil evaporation and vegetation transpiration. While agricultural studies have emphasized the ability of thermal sensors to detect varying temperatures in irrigated vegetation, archaeology has mainly used multispectral sensors for vegetated land. The study shows that in wheat-covered fields, thermal analysis outperforms multispectral and RGB sensors in detecting anomalies associated with archaeological features. Unexpectedly, optimal anomaly detection occurs during mid-morning and mid-afternoon flights, challenging traditional ideas about the timing of thermal analysis. The research highlights the need for renewed interest in the use of thermal cameras for archaeological anomaly detection in cultivated fields. However, further comparative studies between thermal and multispectral analyses on different sites are essential to establish the wider effectiveness of thermal sensors. This study challenges established notions of archaeological aerial thermography and argues for a re-evaluation of sensor selection and flight timing to improve the detection of archaeological features in cultivated fields.