The green guards: Mitigating urban heat island by small scale green interventions in high-density urban areas

RESEARCH QUESTION How do small green space interventions alleviate UHI effect in high-density urban areas with limited spaces in Lanzhou, China? ABSTRACT The development of urbanisation brings not only many benefits but also many problems. The urban heat island (UHI) effect has become a concern in many cities in China. Many studies have indicated what may cause and exacerbate the UHI effect, such as an increasing anthropogenic release, changes in surface cover, urban expansion and others. In recent years, many cities in China have begun to pay attention to and take measures to deal with the climate problems by returning farmland to forest, strengthening green space protection and increasing urban landscape green spaces to tackle the negative impact of UHI effect. However, some cities in the western regions have occupied many land resources due to rapid urban expansion, resulting in high-density cities and populations. For these small and medium-sized cities, limited land resources hinder the development of urban green spaces. This study focused on using small-scale green interventions such as pocket parks as a possible mitigation of the UHI effect in Lanzhou, China. Firstly, relevant literature was reviewed to understand the importance of green areas in cities and their influence on the environment and temperature. Case studies, particularly those on small green spaces, were identified as a potential method of mitigating UHI effect in a microclimate; other green interventions, such as green rooftops and roadside greening, were also included to improve the cooling effect. Secondly, the central area of Chengguan District, Lanzhou, was selected as the main design site. Through site analysis, three available lands and two existing public spaces were utilised for park design and renovation; roadside greening was slightly modified for wider coverage. Finally, an overall layout was developed to show how small vacant lands, building tops and other existing spots were integrated into the project, so as to demonstrate an ideal “green network”. The findings of this study implied that small green spaces could be used to alleviate the UHI effect in high-density cities, suggesting the establishment of a green network based on the fundamental urban structure. Also, a model was provided for other small and medium-sized cities confronting the same issue. DESIGN SITE: Chengguan District, Lanzhou. Chin