Transitional relationships among typical loess geomorphologic types: Loess Plateau of China

Taking the distribution area of typical loess geomorphologic types in the Loess Plateau of China as the study area, this research aims to explore the transitional relationships among typical loess geomorphologic types based on their constructed digital index systems using the data sources of digital geomorphologic database, Landsat TM/ETM+ images and SRTM1 DEM data. Based on Landsat TM/ETM+ images, the digital geomorphologic database was firstly checked and improved using visual interpretation combined with expert knowledge methods, so as to acquire the precise spatial distribution of the typical loess geomorphologic types. Then, the digital index systems for the typical loess geomorphologic types were constructed, which included topographic indexes, quantitative indexes from topographic profile method and remote sensing indexes. Finally, the transitional relationships among the typical loess geomorphologic types were explored based on the constructed digital index systems and the spatial distribution pattern on the remote sensing images. The research results show: loess tableland may transform to loess ridge or loess knoll, and loess ridge may transform to loess knoll. As to morphologic types, loess tableland may transform to loess residual tableland, and then to loess beam tableland; loess wide acclivitous ridge may transform to loess narrow acclivitous ridge, and then to loess knoll ridge. For the valley shape types of the loess ridge and loess knoll, the shallow and high valley may transform to deep and high valley, and then to shallow and low valley. This research is meaningful in the fields such as digital mapping of loess geomorphology, water and soil loss, soil erosion and digital topographic analysis.