Thermal infrared remote sensing and soil gas radon for detecting blind geothermal area

Abstract

Geothermal resources in the Wugongshan area are abundant and most closely associated with faults. Due to the dense vegetation covering the research area, locating the geothermal resources using conventional ground technologies is costly and challenging. This paper proposes and implements a novel method in the area under examination. More specifically, remote sensing information (Landsat 8) and known geological information are used to delineate the geothermal target area. On January 19, 2021, the land surface temperature in the study area ranged between 7.7 and 21.2 °C. Combining the geothermal geological features of the regional area, two areas, namely Tangjiashan and Sanjiang, are delineated as geothermal target areas. The probable location of faults is determined by measuring the soil gas radon concentration. The relative coefficient KQ of radon activity attained in profiles varies between 1.7 and 13.2. The average values of KQ between different areas are ranked as Wenjia > Tangjiashan > Hongjiang > Sanjiang. Generally, areas with higher KQ of radon activity have higher land surface temperature (LST). Thus, the KQ and LST can be used to evaluate the shallow geothermal potential. Finally, by integrating the interpretation of remote sensing and soil radon measurements, the fault location is identified, and the result is successfully used to guide the drilling of geothermal wells in the Tangjiashan area.