Coupling performance of pavement albedo and soil moisture in linear street canyons: Thermodynamic mechanisms and engineering thresholds for heat mitigation

This study investigates summer thermal mitigation mechanisms for linear urban infrastructure in cold regions, addressing the critical engineering challenge of extreme heat stress in linear street canyons. Using Westward Avenue at Xi’an Jiaotong University Innovation Port as a representative megastructure canyon, this research integrates field measurements, validated ENVI-met microclimate simulations (MAPE < 10%), and a dual-factor controlled experiment to quantify surface energy balance (SEB) modifications under continuous enclosure. The results indicate that: (1) The existing infrastructure acts as a high-intensity thermal corridor during midday (UTCI > 45°C); (2) The conventional engineering approach of solely increasing pavement albedo fails in ventilation-restricted spaces, frequently exacerbating heat stress due to the radiation trapping effect; (3) From a sustainable engineering perspective, a scenario-specific transition point around 25% soil volumetric water content is identified. Beyond this level, latent heat flux dominates energy dissipation, enabling high-albedo materials to transition from "heat traps" to "thermal barriers". This coupled strategy reduces WBGT by 3–4°C. Ultimately, this study proposes a physics-based "humidity-first, albedo-coordinated" framework, providing actionable quantitative guidelines for pavement material selection, blue-green infrastructure integration, and irrigation management in high-density urban infrastructure.