Objective Urban lake wetlands possess significant regulatory functions and environmental benefits for regional environments. A synergistic layout of water and green spaces can enhance their temperature and humidity effects. Focusing on maximizing the regional environmental effects of urban lake wetlands, it is of great practical significance for the planning and protection of the built environment of urban lake wetlands to strengthen and optimize the construction of green spaces in the surrounding built environment, and to explore the coupling relationship between the morphological composition and layout structure of green spaces in the built environment and the temperature and humidity effects of urban lake wetlands.

Methods Taking Lingjiao Lake and its surrounding 300 m built environment green space in the main urban area of Wuhan as the research area, this area is characterized by dense buildings and a complex composition of the built environment, including green spaces, plazas, commercial areas, and residential zones. In this study, the diurnal air temperature and relative humidity in July 2024 were measured as indicators. Using a combination of transect-based quantitative measurements and land use regression (LUR) models, a comprehensive assessment and data statistical analysis were conducted to systematically investigate the spatiotemporal characteristics of air temperature and relative humidity effect field of urban lake wetlands.

Results This research comprehensively analyzed the factors influencing air temperature and relative humidity in the built environment surrounding urban lake wetlands, based on a combination of LUR models. The results indicate that: 1) The LUR model based on the key influencing variables consists of water area, surrounding green space and built environment factors within 300 m buffer and meteorological factors and indicators of air temperature and relative humidity were successfully established, with the adjusted R ² of 0.607 and 0.779 for air temperature and relative humidity, respectively, and the adjusted LOOCV R ² of 0.763 and 0.957, respectively. Based on the correlation analysis of LUR model variables, the prediction variables for air temperature are ρ_T100, ρ_T25, D_R, H_B25, and I_LA, while ρ_T50, ρ_B25, P_W25, I_LA, D_B, and T for relative humidity. 2) The coupling of urban lakes and wetlands with surrounding green spaces has a significant effect on improving temperature and humidity. For air temperature, the combined blue-green effect of the 300 m buffer zone (T_{300 m} −T_Lake) is 0.58 ℃, with a gradient of 0.19 ℃/100 m; for relative humidity, the combined blue-green effect of the 300 m buffer zone (φ_RHLake −φ_{RH300 m}) is 2.11%, with a gradient of 0.70%/100 m. 3) The key influencing factors of air temperature and relative humidity in different buffer zones and surrounding green spaces vary significantly. Within a 50 m buffer zone, ρ_T is the only positively correlated variable with T; Regarding RH, the influencing variables are ρ_T, P_W, and P_G. Within a 100 m buffer zone, ρ_B has a significant impact on T, while ρ_T is the most significant variable affecting T and RH; Regarding RH, the significant influencing variables include P_W, D_R, and ρ_T. Within the buffer zones of 200 m and 300 m, ρ_B, ρ_T, and F_SV (sky view factor) have significant effects on T and RH. In summary, the lower the traffic density, the higher the green space canopy density, and the larger the leaf area index, the more significant the synergistic cooling effect of blue-green space.

Conclusion This research, from the perspective of blue-green collaboration, examines how urban built environment and land use factors affect temperature and humidity in terms of mechanism, intensity, and scope. According to the LUR models consists of blue-green factors, built environment factors, and meteorological factors, it summarizes the spatio-temporal characteristics of the temperature and humidity effect field of urban lake wetlands, and reveals the associated effects of blue and green spaces and their physical-level spatial interactions, providing support for enhancing the environmental effects of urban lake wetland. Based on the findings, the following strategies for improving the temperature and humidity regulation of urban blue-green space systems are proposed: 1) Control the proportion of transportation infrastructure around urban water bodies; keep main roads at least 60 m away from water spaces to maximize the regulatory function of blue-green spaces. 2) Protect urban blue lines, green lines, and blue-green space effect lines; limit building density to an approximately 0.35 within 300 m buffer. 3) Select plant communities with high leaf area index (I_LA>2.0), canopy density (ρ_C>0.77), and large crown width for green spaces around lakes, optimizing green space structures and increasing the proportion of multi-layered vegetation.