Calibrated Thermal Remote Sensing for Coastal Groundwater Detection: A UAV-Based Methodology for Rapa Nui

Authors: Weston Coleman, Ezra Coburn

Field of Study: Science, Technology, Engineering, and/or Math

Faculty Mentors: Carl Lipo

Easel: 5

Timeslot: Morning

Abstract: Freshwater availability on Rapa Nui (Easter Island, Chile) has fundamentally influenced settlement patterns and the island's remarkable archaeological landscape. As climate change threatens water security in this isolated territory, understanding groundwater systems has become essential for sustainability planning. This study employs small UAVs with infrared imaging to identify coastal groundwater seeps through their distinct thermal signatures—groundwater is cooler than the warmer surrounding ocean. These freshwater discharges create surface thermal gradients serving as proxies for discharge volumes. To address challenges in thermal remote sensing over dynamic coastal interfaces, this research developed a Python-based calibration framework correcting for confounding variables: sensor drift, solar reflectance, terrestrial heat transfer, oceanographic conditions, and temporal inconsistencies. This approach enables consistent integration of thermal data from overlapping images acquired during coastal flight transects, facilitating the construction of groundwater discharge maps with unprecedented spatial resolution.