Numerical study on the coupling effect of river attributes and riverside building forms on the urban microclimate: a case study in Nanjing, China

Urban rivers play an important role in mitigating urban heat islands. However, a coupling analysis of river attributes and waterfront architectural forms is lacking. Most existing studies have used a single urban scale and research method and lack comprehensive application. Satellite remote sensing data were used in this study to examine the cooling law of rivers at the macroscale. At the microscale, a microclimate simulation was used to study the influences of river attributes, climatic conditions, and architectural spatial morphological characteristics on the cooling effect of rivers. The river cooling effect is positively correlated with river width, where a temperature drop caused by a 100m river width can reach 0.75°C. The cooling effect of rivers is easily influenced by the surrounding built-up areas; this effect is more significant for rivers greater than 40m wide. In the study of the index of architectural space form, their influence on the thermal environment of the riverside is ranked from high to low: building density, building riverside enclosure degree, building height. The findings provide guidance for the planning and design of riverside buildings from the perspective of thermal environment optimization to construct sustainable cities.