Tan DEM‐X Preserves the Relationship Between Hilltop Curvature and Erosion Rate in the Qilian Shan

Abstract

Hilltop curvature (C_HT) can record erosional responses to tectonic forces and/or climate change. Although C_HT has a linear relationship with the erosion rate, which is a significant advantage over traditional indicators, it is not widely used, mainly because it requires high‐resolution terrain data. Previous studies show that terrain steepness is strongly correlated with catchment‐wide erosion rates in the Qilian Shan. This relationship enables us to test the potential of C_HT based on medium‐resolution terrain data (e.g., Tan DEM‐X with a resolution of ∼12 m) as an indicator of the erosion rate. We selected three typical sites in the Qilian Shan with evenly spaced ridge valleys and a continuous soil cover. At each site, we produced a high‐resolution digital surface model (DSM) using uncrewed aerial vehicles (UAVs), and then compared C_HT from the UAV DSM with that from Tan DEM‐X, via LSDTopoTools. The results show that both Tan DEM‐X and the UAV DSM record similar spatial patterns of C_HT, although the magnitudes vary between the three selected areas. We then examined the relationship between C_HT based on Tan DEM‐X and the catchment‐wide erosion rate in the Qilian Shan. C_HT has a linear relationship with the erosion rate in an area of clastic rocks, where the erosion rate is below 400 mm/Kyr. C_HT extracted by Tan DEM‐X is superior to the mean basin slope in predicting the erosion rate in this clastic rock landscape. Overall, our results demonstrate the utility of Tan DEM‐X in calculating C_HT to indicate the erosion rate.