Looking to the Skies: Realising the Combined Potential of Drones and Thermal Infrared Imagery to Advance Hydrological Process Understanding in Headwaters

Abstract

In river systems, headwater networks contain the vast majority of the stream length. Thus, climate and land-use change in headwaters have disproportionate impacts on downstream ecosystems and societies that rely on them. Despite decades of hydrological research, difficulties in observing hydrological properties across scales means that scientific knowledge of processes driving streamflow in headwaters remains limited. However, the recent emergence of two complementary technologies, drones and thermal infrared (TIR) remote sensing, has potential to collect data at scales and resolutions needed to advance hydrological process understanding in headwaters. In this commentary, we explain how drone-based TIR can offer unique high-resolution observations of surface connectivity and headwater network dynamics across multiple spatio-temporal scales. We explore the current state-of-the-art of drones and TIR imaging in the hydrological sciences, highlighting the potential benefits but also steps that will need to be taken to release these technologies' full potential. We finish by contending that drone-based TIR is particularly well-placed to bridge the current gap between field (point) observations and model simulations to provide the improved hydrological understanding needed for a changing world.