风蚀坑形态-动力学研究进展

A Review on Morphodynamic Processes of Blowouts

风蚀坑是沙质海岸、湖岸及干旱、半干旱区沙质草原地区受风蚀作用形成的洼地。受风蚀坑地形的影响,坑内气流的风速、风向发生了变化,通过输沙过程的局部差异改变了风蚀坑的蚀积格局,并对风蚀坑形态进行改造。而形态的变化又反作用于近地表气流,由此产生风蚀坑形态-动力学的响应与反馈。总结并扼要评述国内外近年来风蚀坑形态-动力学及其发育演化方面的研究进展,分析现有研究的不足,以期对今后此类研究提供借鉴。

Blowouts are depressions produced by wind erosion, which occur on sandy coasts or lake shores and sandy grasslands in arid and semi-arid rergions. Topographic steering changes the velocity and direction of airflow within the blowout. Then a local difference in sediment transport exists, which changes the pattern of erosion and accumulation and reforms the morphology of the blowout. Topographic changing reacts on the near-surface airflow and forms the feedback and response mechanism between morphology and dynamics.This article briefly reviews the processes of morphodynamic and evolvement of blowouts, and analyzes its study trends, hoping to provide some reference for similar researches in the future. Although lots of progresses have been made in study of dynamic and evolvement of blowout, there are still many aspects need to be improved. First of all, airflow patterns in blowout are complicated, because of the limited field data, we often get an unreal construction and a poor understanding of airflow patterns. In order to aquire more sufficient field data and precise analysis, more intense observation sites and continuous observations are needed. Secondly, temporal and spatial scales of previous researches in blowout are relatively small. Most of the research just focused on the dynamics and evolvement of individual blowout, but ignored the others＇ in the same region; and limited observations to the current developmental situation, but ignored the processes or morphology in the past and future. In order to summarize a relatively complete evolutionary pattern of blowouts tentatively, the large-scale and long-term monitorings to the blowouts, which in variety of developmental phases are requisite.At last, compared with foreign researches which made certain achievements in coastal blowouts, domestic researches in evolutionary processes of inland blowouts which developed in different conditions and different genesises are deficient. Many blowouts which in various developmental phases occurred in arid and semi-arid regions in north China, evolutional laws could be summarized according to their conditions and morphological characteristics. Then make comparisons with relevant research results of coastal blowouts, and validate their applicability in terrestrial environments.