An integrative social-ecological approach for urban boundary mapping

Clear definition and accurate delineation of urban boundaries are the prerequisite for urban-rural studies. However, urban boundaries have been typically mapped based either on biophysical or socio-economical properties, resulting in barriers in conducting integrative social-ecological studies. Here, we developed a new approach that integrates the biophysical and socio-economical perspectives for urban boundaries mapping, and tested the approach in mainland of China. First, we divided the study area into 1 × 1 km grids, some of which were classified into urban and rural based on Points of Interest (POIs) and official urban-rural classification. The classified grids were then served as training samples to determine thresholds of impervious surface percentage (ISP) for further urban-rural separation. Combined threshold of ISP (biophysical properties) with connectivity to administrative urban centers (socio-economical properties), the unclassified grids were assigned as either urban or rural. Finally, all urban grids were merged to create China's urban boundary (CUB). The integrative approach improved the accuracy of town mapping and village mapping by 15 % and 17 % respectively, compared with existing urban boundary products. Our approach is thus capable to improve mapping accuracy and provide urban boundary for social-ecological studies in urban-rural areas.