DEM-based analysis of tectonic geomorphologic characteristics and tectonic activity intensity of the Dabanghe River Basin in South China Karst

Abstract The Dabanghe River Basin, in the west of Guizhou Plateau, consists of numerous prominent geological structural features, such as the Shuicheng–Wangmo, Yadu–Ziyun, and Yongningzhen Faults, the Huangguoshu Waterfall, and the Guanjiao Knickpoint. The topographic conditions and structural systems are highly complex, making this a suitable area to study neotectonics. However, research on the geomorphology of the region is lacking. Combined with geomorphic parameters, quantitative exploration of tectonic geomorphic and tectonic activity in the Dabanghe River Basin is of great significance to reveal the formation of the Huangguoshu Waterfall, the development of landforms in western Guizhou, and the regularity of uplift of Guizhou Plateau. Therefore, based on a Digital Elevation Model, GIS software extracted and calculated six geomorphic parameters of the basin: Hypsometric Integral, Asymmetry Factor, Basin Shape Ratio, Stream-Gradient, and Valley Floor Width–Valley Height Ratio (VF) indexes. The tectonic geomorphic characteristics of the Dabanghe River Basin were analyzed, combined with the tectonic activity level classification method, and the Index of Relative Active Tectonics (IAT) of each sub-catchment was calculated. The geomorphic parameters of the basin were found to indicate its geomorphic characteristics well. The tectonic activity in the study area midstream is the most active, and the geomorphic evolution of some upstream and downstream reaches is affected by lithology, topography, and structure. The tectonic geomorphology of the basin is significantly affected by the fault system. Under the control of the Yadu–Ziyun Fault, the tectonic activity in the basin gradually weakens from west to east, and the differential tectonic activity (strong in the mid-reach and eastwards decrease) is consistent with observed seismic intensity. It is confirmed that our research results are consistent with the regional geological background and geomorphic characteristics through field geological survey. Therefore, this study confirms that the use of tectonic geomorphic parameters to classify active tectonics can be an important method to evaluate the stability of the crust in the region and further extends the application of geomorphic parameters in tectonics.