Comparing Small Water Bodies’ Impact on Subtropical Campus Outdoor Temperature: Measured vs. Simulated Data

Abstract

This study investigates the impact of small water bodies on outdoor temperatures in their vicinity, using a campus located in the subtropical region of Taichung City, Taiwan, as the research subject. By employing on-site measurements and Computational Fluid Dynamics (CFD) simulations, we examined their temporal and spatial influence, as well as comparisons between actual measurements and software predictions. Key findings include the following: (1) Small water bodies exhibit discernible temperature-regulating effects on their surrounding areas. While the influence diminishes with distance, this attenuation is not stark, and is potentially constrained by the water body’s patch size. (2) Regulatory effects vary between day and night. In summer, temperature reductions of up to 3.5 °C (simulated) and 3.2 °C (measured) were observed. Conversely, in winter, daytime temperatures around water bodies may rise by up to 3.9 °C. (3) Discrepancies between CFD simulations and actual measurements, influenced by fluctuations in Global Horizontal Irradiation (GHI), range from +2.5 °C to −1.8 °C. During high GHI periods, measured values surpass simulations, whereas during low or zero GHI conditions, simulations exceed measurements. Moreover, high regression analysis R2 values validate the feasibility of CFD simulations for predicting water body-induced temperature changes. Insights from this study offer valuable guidance for urban planners and policymakers seeking sustainable urban climate management strategies.