Evaluating the suitability of different terrains for sustaining human settlements according to the local elevation range in China using the ASTER GDEM

The topographical suitability assessment of human settlements (SAHS) creates a solid foundation for regional population distribution and socio-economic development. Local elevation range (LER) is an important factor that can be used to assess the suitability of different terrains for sustaining human settlements. However, current digital elevation model (DEM)-based LER products suffer from some challenges typically because of their subjectively selected neighborhood scales and coarser spatial resolution. In this study, we initially determined the optimal statistical window and then calculated the appropriate LER with the finer resolution data of the Advanced Spaceborne Thermal Emission and Reflection Radiometer Global DEM (ASTER GDEM) products for China. Then, the appropriate LER was used to evaluate the topographical SAHS and its correlations with the national gridded population distribution (1 km × 1 km) in 2010. The results show that the optimal statistical window for calculating a 1 arc-second (about 30 m) resolution GDEM LER for China can be determined using a 51 × 51 grid unit (width × height) within a rectangular neighborhood, corresponding to an area of about 2.34 km². Secondly, the LER values in the southern and western China were greater than those of the north and east, showing a trend which consistently reflects the general spatial features of landforms. Finally, the relationship between GDEM LER and population density was highly correlated with the R² value of 0.81. It showed that 85.22% of the Chinese population was located in areas where the LER is lower than 500 m. The topographically suitable area within China decreased from the southeastern coastal zone towards the northwestern inland areas due to transition from plains and basins to plateaus and mountains. The total area of moderate to high suitable level was 423.84 × 10⁴ km², or 44.15% of the total land area, with 88.17% of the national population. Our study demonstrates the usefulness of appropriate LER in evaluating the topographical SAHS as well as its significant impact on population distribution.