How green are residential areas? An analysis of community greening emerging multi-source geo-data

Urban residential greening provides opportunities for social integration and physical exercise. These activities are beneficial to promoting citizens mental health, relieving stress and reducing obesity and violent crimes. However, how to measure the distribution and spatial difference of green resources in urban residential areas have been controversial. This study takes the greening of urban residential units in Shenzhen City as its research object, measures the various greening index values of each residential unit, and analyses the spatial distribution characteristics of residential greening, regional differences and influencing factors. Large sample of street view pictures, urban land use and high-resolution remote sensing image data are employed to establish an urban residential greening database containing 14,196 residential units. This study proposes three greening indicators, namely, green coverage index, green view index, and accessible public green land index, for measuring the green coverage of residential units, the visible greening of surrounding street space and the public green land around, respectively. Results show that (1) the greening level of residential units in Shenzhen City is generally high, with the three indicators averaging 32.7%, 30.5% and 15.1%, respectively; (2) the types of residential greening differ per area; and (3) the level of residential greening is affected by development intensity, location, elevation and residential type. Such findings can serve as a reference for improving the greening level of residential units. This study proposes an accessible public green land index as a measure for the spatial relationship between residential units and surrounding green spaces. It suggest that future green space planning should pay more attention to the spatial distribution of public green land, and introduce quantitative indicators to ensure sufficient public green lands around the walking range of residential areas.