Urban Blue Spaces and Urban Heat Island Mitigation: A Bibliometric and Systematic Review of Spatiotemporal Dynamics, Morphology, and Planning Integration

Urban blue spaces, including rivers, lakes, and ponds, are increasingly recognized as nature-based solutions for mitigating the Urban Heat Island (UHI) effect. However, fragmented evidence and inconsistent evaluation frameworks have limited their effective integration into climate-adaptive urban planning. This study conducts a comprehensive bibliometric analysis and systematic review to synthesize current knowledge on the cooling effects of urban blue spaces. A total of 110 peer-reviewed publications published between 2015 and 2025 were retrieved from the Web of Science Core Collection and analyzed using the Bibliometric-Systematic Literature Review (B-SLR) framework. The results reveal a rapidly growing research field characterized by increasing interdisciplinary integration. Evidence consistently indicates that the cooling effects of blue spaces exhibit pronounced diurnal and seasonal variability, highlighting a “diurnal paradox” of daytime cooling versus nighttime warming risks, with stronger impacts in summer than in winter. Cooling performance is governed by non-linear morphological thresholds regarding size, shape, spatial configuration, and upwind location, where aerodynamic ventilation is critical for extending the cooling range. Moreover, the interaction between blue spaces, building morphology (gray infrastructure), and green infrastructure plays a decisive role: specific density thresholds in built environments can constrain cooling diffusion, whereas synergistic blue–green integration significantly enhances thermal regulation through coupled evaporative, shading, and ventilation processes. Overall, this review demonstrates a clear shift from isolated temperature-based assessments toward systemic, planning-oriented approaches emphasizing multi-scale integration and context-sensitive design. The findings provide operational parameters and demand-based strategies for optimizing blue infrastructure in climate-resilient urban planning.