Do reconstructed landforms have multifractal characteristics? A case study at an opencast coalmine dump in the loess area of China

Abstract

Opencast coal mining causes large changes in landform. The geomorphological features of the reconstructed landform have not been fully understood in the loess area. To quantify the characteristics of the reconstructed landform, multifractal analysis and Principal Component Analysis (PCA) were applied to classify three soil dumps, located at the Antaibao opencast coalmine in China. Most parts of the reconstructed soil dumps had multifractal characteristics. Multifractal parameters reflected heterogeneity of the reconstructed landform from surface relief, regularity and variance in elevation, and the results of PCA further provided a good explanation of the differences and similarities among the three soil dumps. Sub-areas of the South Dump (S1, S2, S3, and S4) were clustered together and this grouping was explained by relatively high D(0), ɑmax and D(q)min, whereas sub-areas of the remaining dumps were sparsely distributed. Long-term restoration and soil erosion may cause the homogenization of the reconstructed landform. Moreover, multifractal parameters, D(q)min, D(0), D(1), D(2), ɑmin, and f(ɑmin) were significantly correlated with Normalized Difference Vegetation Index (NDVI), suggesting susceptibility of the restored vegetation to landform development. Therefore, to improve revegetation practice, micro-topographic measures and silviculture technology are both needed in post-mining areas. The micro-geomorphological patterns could not only improve the efficiency of water use, but also provide a basis for the evolution of geomorphological research in the loess area of China.