Effect of land use change on summertime surface temperature, albedo, and evapotranspiration in Las Vegas Valley

Abstract

Urban surfaces affect the surface energy budget, which plays a defining role in outdoor water requirements changing an area's evapotranspiration. They also affect thermal comfort levels for humans, animals, and vegetation by causing the surface temperature to vary. This study analyzes the effects of land use change on the surface albedo, land surface temperature (LST), and evapotranspiration (ET) of the arid Las Vegas Valley (LVV). The changes in land use considered include transitions from barren and rural surfaces into urban surfaces covered with residential, commercial buildings, roadways, and turf grass. The impacts of these changes were determined by analyzing trends over the summer periods from 1990 to 2017. Remote sensing data acquired by Thematic Mapper (TM) and Operational Land Imager (OLI) aboard Landsat satellite were used to retrieve various geophysical characteristics, including albedo and LST. The ET was estimated using the Mapping of Evapotranspiration using Internal Calibration (METRIC) model with remote sensing input data. The geophysical characteristic trends, in response to urban land use change, were quantified using Mann Kendall's trend analysis.The results showed that commercial buildings and roadways are the main contributors to increased LST. Land use change from rural to commercial buildings decreased surface albedo by 0.4 ± 0.01 with a Sen's slope (S) of 0.001–0.003 units/summer/year, and increased temperature by 7 ± 0.2 K with S = 0.2 and 0.4 K/summer/year. Turf grass removal increased temperatures by 20 ± 0.3 K, while urbanization, in general, increased LST by 5 ± 0.3 K. Roadway surfaces, primarily covered with asphalt, were the main contributors to temperature increase of LST 17 ± 0.1 K and S = 0.2–0.8 K/summer/year, while decreasing albedo by 1 ± 0.01 with S = 0.001–0.003 units/summer/year. Turf grass development maintained LST in the valley throughout the study period, showing significant ET increase (S = 0.04–0.06 mm/summer/year), with an average increase of 1 ± 0.07 mm/day. This study can help water managers and urban planners to understand the role of land use change in irrigation water demand and urban thermal comfort.