UAV Thermal Mapping as a New Tool to Detect Subsurface Moisture and Document Baseline Environmental Conditions

The California High-Speed Rail is currently planning a rail corridor through the San Gabriel Mountains. The alignment will require tunnels up to approximately 600 m deep and crossing through the San Gabriel Mountains in the SR 14 area. This study utilized repeated optical and infrared unmanned aerial vehicle (UAV) aerial imagery to document the baseline environmental conditions overlying one of the future high-speed rail tunnels. Images provide vegetation and soil moisture patterns along the surface route of the corridor for future comparison when the tunneling segments are bored. Analysis of reflectance data revealed subsurface water flow in the Bear Creek-Sand Canyon Creek Study Area. Using UAVs is considered an effective new tool to detect large-scale and discrete environmental conditions, perhaps undocumented or unobservable, via standard mapping tools. Setting detailed baseline conditions is important to identify changes that may occur because of future tunneling.