Simulating Near-surface Soil Temperature and Water on Sagebrush Rangelands: A Comparison of Models

The objective of this study was to determine if uncalibrated soil water and temperature models, varying in complexity and data requirements, could simulate spatial and temporal variations in near-surface soil microclimatic conditions. The SWRRB, Opus, and SHAW models were compared on their ability to address small scale spatial and temporal variations in near-surface (0-5 cm) soil microclimatic conditions on rangelands. The models were used to simulate soil temperature and water at various depths at two locations: One under a sagebrush plant and the other in the interspace between plants within a sagebrush-grass plant community. Uncalibrated simulations were run for one year where the models all performed well at simulating annual sinusoidal patterns in soil temperature at the 1-cm depth under sagebrush and interspace locations. The models performed best during the fall and spring and poorest during the winter. SHAW simulated both the spatial variability between and the day-to-day temporal variations within each location more accurately than did the other two models. All three models had difficulties simulating soil water at the 1-cm depth throughout the year. SHAW and Opus performed quite well at simulating soil water at the 30-cm depth under sagebrush, but SHAW performed better in the interspace at the same depth.