Loess tableland geomorphic classification criteria and evolutionary pattern using multiple geomorphic parameters

Abstract

The geomorphic evolution of loess tablelands (LTs), loess ridges (LRs) and loess hills (LHs) affects the availability of local farmland. The present study distinguished the evolutionary stages of different loess geomorphic units using mathematical morphology and analyzed the evolutionary process from LT to LR to LH from geomorphic characteristics and the physical meaning of the geomorphic parameters. Remote sensing images were used to interpret the LT-LR-LH landforms in the Heshui County watershed. The interpreted results indicated a gradual decrease in LT and increase in LR and LH in the Heshui County watershed from southwest to northeast. Geomorphic parameters were used to assess the evolutionary stage and establish the classification criteria. The results showed that geomorphic parameters were useful to distinguish the evolutionary stages of different loess geomorphic units, and circularity (C) played a key role in the setting of classification criteria. An evolutionary pattern of LT-LR-LH landforms was quantified and visualized. Generally, the evolution of loess tablelands followed a trend from LT to LR to LH with the further subdivision of LT-LR-LH into 9 stages of loess geomorphic units. This study provides new insight into the evolution of LT-LR-LH loess landforms and revealed the location where LTs disappeared. These classification criteria and evolutionary patterns may be extended to other loess areas to assess the extent of landform evolution.