EXAMINING GROUNDWATER AND SURFACE WATER INTERACTIONS TO DETERMINE THE EFFECTS OF ANTHROPOGENIC NUTRIENT LOADING ON STREAM AND COASTAL WATER QUALITY

Over the past decade, thermal infrared (TIR) imaging has become increasingly relevant as a reconnaissance tool for locating groundwater discharges (submarine groundwater discharge, stream baseflow) in regions where there is a thermal contrast between groundwater and surface waters. Satellite data acquisition, aircraft surveys, and ground-based imaging have served as means for TIR data collection, but all of these methods have significant drawbacks (e.g. low resolution satellite data, expensive aircraft surveys, and time-intensive ground-based imaging). With recent technological advances in unmanned aerial vehicles (UAVs, “drones”), the availability of UAV-TIR technology has added new capacity and flexibility for high-resolution imaging of groundwater discharges. We report our findings in the Kaneohe region of Hawai’i, where groundwater is suspected to be a significant source of nutrient loading into the otherwise naturally-oligotrophic waters of Kaneohe Bay, which have experienced increased nutrient loading from anthropogenic sources (e.g. cesspools, agriculture) over the past few decades. Our study evaluates groundwater contributions to surface water contamination by pairing UAV-TIR with numerical modeling and field measurements to locate, quantify, and characterize groundwater discharges.