A 30-year (1984-2013) record of annual urban dynamics of Beijing City derived from Landsat data

Although mapping activities of urban land change have been widely carried out, detailed information on urban development in time over rapid urbanization areas would have been lost in most studies with multi-year intervals. Here we provide a two-stage framework of long-term mapping of urban areas at an annual frequency in Beijing, China, over the period from 1984 to 2013. Classification for each year was carried out initially based on a number of Landsat scenes within that year using spectral information from a base image plus NDVI time series derived from all scenes. A temporal consistency check involving both temporal filtering and heuristic reasoning was then applied to the sequence of classified urban maps for further improvement. We assessed this time-series of urban maps based on two schemes. One is change detection in rapidly developing areas over the past three decades, and the other is accuracy assessment over the whole region in four selected years (i.e., 1984, 1990, 2000 and 2013). Based on validation using independent samples, the OAs (overall accuracies) of these four years are 96%, 93%, 92% and 95%, respectively. Meanwhile, the average accuracy of change detection for all years is 83%. In addition, the proposed temporal consistency check was found to be able to make considerable improvements (about 6%) to the overall accuracies and results of change detection. The resultant urban land sequence revealed that the average growth rates were 47.51 ± 4.17 km2/year, 34.65 ± 2.90 km2/year and 99.48 ± 1.3 km2/year for 1984-1990, 1990-2000 and 2000-2013, respectively.