Drone remote sensing to define heat exchange between urban surfaces and stormwater runoff

ABSTRACT Urban water bodies are often subject to high runoff temperatures from heat exchange between rainfall and urban surfaces; however, this process can be difficult to define due to the complexity of spatially heterogeneous urban areas. This research seeks to improve our understanding of heat exchange in urban stormwater runoff by integrating in situ measurements of runoff temperature with land surface temperature data captured in high spatial resolutions by a drone. To do so, this study monitored four urban catchments in Milwaukee, WI that are dominated by different land surfaces (concrete parking lot, asphalt road, black bitumen roof, and grass). Results indicate that land surface temperature was variable among common land surface types (1.34–2.24 °C), with higher variations in surfaces subject to foot and vehicular traffic. In addition, the temperature of runoff from impervious surfaces responded differently between buildings and those with a ground subsurface, with higher event mean temperatures from concrete (21.4 °C) and asphalt (21.9 °C) ground surfaces as compared with the bitumen roof (19.8 °C), despite similar initial surface temperatures. Ultimately, these outcomes demonstrate how drone remote sensing of land surface temperature and in situ monitoring can be integrated to understand heat exchange processes in urban stormwater runoff.