Simulation Of Geomorphic Evolution Of Loess Watershed Based On Archaeological Remains Information

China's Loess Plateau is regarded as one of the most unique and valuable geographic regions for geoscience research. This area,as a complete geomorphic unit,has attracted much attention due to its severe soil erosion. Gully erosion is a common type of loess erosion. It is the main component of soil loss on the Loess Plateau and it plays an important role in shaping the topography of the Loess Plateau. The study of historical geomorphic evolution and gully erosion processes in Loess Plateau is of great significance for exploring the evolutionary mechanism of loess geomorphology and supporting the conservation of water and soil on the Loess Plateau.In this research, selected the archaeological site of Wucheng Remains as the research area where was discovered during a fieldwork in Loess Plateau. Spatio-temporal simulation of historical geomorphic evolution of this area was conducted.Topographic surfaces of Wucheng watershed in different historical times were reconstructed. Furthermore, a sequence of DEMs that depicts topographic changing in history was obtained. The main contents of this research are as follows:1.Geomorphic information extraction of Wucheng Remains based on historical geographyVisited Wucheng Remains and the surrounding area. Investigated the distribution patterns and topographical structures of Wucheng by means of GPS sampling, UAV aerial photography and some other techniques. Extracted the hidden ancient geomorphological information of Wucheng Remains. At the same time, collected the historical and cultural documents of geographical information.2. Modeling of loess geomorphic evolution based on LS and CAAccording to the theories of loess stratigraphy and soil erosion, discussed the erosive characteristics and evolutionary tendencies of the past Loess Plateau. Then,based on analysis of loess erosion, selected slope Length and Steepness factor (LS factor) as the main driving force for simulating loess erosion in the model. After that,based on methodologies of Cellular Automata (C A) and Digital Terrain Analysis (DTA),adopted CA as the framework of this model. Regarding the complexity and uncertainty of loess erosion processes,introduced the stochastic factor in order to improve model's robustness. Besides, invented the concept of soil particle as the basic unit for simulation.Finally, obtained a sequence of DEMs of research area as results through model running and each DEM in this sequence correspond to a historical time.3. Temporal calibration of evolution model based on foundation surface of ancient city remainsThe geomorphic evolution is a "lost annual ring" that it is difficult to acquire time nodes of loess landform in historical periods. While the discovery of Wucheng Remains offers an important clue about the ancient loess geomorphology. Therefore,the research selected Wucheng as the study area, reconstructed the foundation surface of Wucheng Remains and dated its historical time. Through the correlation analysis between the foundation surface of the ancient city and the simulated DEM sequence, achieved the temporal calibration of the simulation results.