Impact of Urban Water Networks on Microclimate and PM2.5 Distribution in Downtown Areas: A Case Study of Wuhan

Rapid urbanization in China has resulted in highly dense urban forms and marked reductions in ecological resources, which in turn have caused severe urban heat islands and PM2.5 pollution. In typical cities with a water network, such as Wuhan, the use of water resources to improve the urban climate environment has become an urgent issue. In this study, we explored the impact of water networks on the microclimate and PM2.5 distribution in Wuhan by using multi-source remote sensing data and the weather research and forecasting model. Our results indicated that the water network has a blocking effect on PM2.5. Taking pollutant sources into consideration, the coverage of the water surface is positively correlated with a PM2.5 concentration of 0.606-0.703; the concentration of PM2.5 over suburban lakes with an area larger than 60 km2 is approximately 6%-13% higher than that of the surrounding land surface. We also found that the water network reduced the average temperature of the downtown and the urban hinterland at noon by 1 K and 0.5 K, respectively, and increased the height of boundary layer at night by more than 60 m-an approximately one-third increase-which helped decrease the level of PM2.5. In addition, the impact of water bodies located in different ring loops on the downtown microclimate varied significantly. Water bodies located downtown significantly increased the night wind speed in downtown areas to as much as 2 m/s, while those in nearby and outer suburbs increased the wind speed downtown by more than 1 m/s at noon.

Automated summary

Rapid urbanization in China has led to dense urban forms and decreased ecological resources, resulting in urban heat islands and PM2.5 pollution. The study found that water networks have a blocking effect on PM2.5, reduce surface temperature, increase nighttime boundary layer height, and can help decrease PM2.5 levels.