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Loess caves are a special but widespread geological hazard in the Loess Plateau region. Due to its complex spatial characteristics, hidden development location, and various influencing factors, the early identification of loess caves currently faces many challenges. This paper briefly introduces the types, development characteristics and formation mechanism of loess caves by using the method of literature review. Then, it summaries the existing methods for early identification of loess caves from traditional manual field survey, rapid identification of caves in small watersheds and geophysical exploration of underground caves, and reviews the advantages, disadvantages and application effects of various methods, pointing out that the early identification of loess caves currently faces great difficulty in identification. It is noted that the early identification of loess caves is currently facing many challenges, such as the difficulty of identification, the low accuracy of identification and the fragmentation of identification methods. The study concludes that the 3D measurement and modeling endoscopy has a broad prospect in identifying the internal structure and spatial morphology of caves. Strengthening the basic research on the physical properties of loess and developing efficient interpretation software and algorithms are the key links to improve the existing geophysical detection accuracy and realize accurate modeling of loess caves.The establishment of an integrated“Sky-Air-Surface-Subsurface” system for early identification of loess caves is the best choice for rapid and refined identification of loess caves in watersheds in the future. The research results provide a reference for the early identification of loess caves and the monitoring and early warning of geological hazards caused by subduction of loess caves in the future. [ABSTRACT FROM AUTHOR]

Loess is a kind of Quaternary loose deposits. There are many primary and secondary pores and cracks in the loess, which provide preferential channels for water to enter the soil and form preferential infiltration phenomenon. This water movement mode is called preferential flow. The existence of preferential infiltration and preferential flow is one of the main causes of landslide and other loess geological disasters, so it is necessary to study the phenomenon of preferential infiltration. Based on the discussion of the classification of loess dominant structural planes by previous scholars, this paper puts forward the classification method of loess preferential channels, then discusses the preferential flow classification of domestic and foreign scholars and the main research methods, and analyzes their advantages and disadvantages. This paper summarizes the main infiltration models of the current preferential flow and the characteristics of the governing equations representing the models, analyzes and discusses the deficiency of present research and the development direction in the future at the end. [ABSTRACT FROM AUTHOR]