巴丹吉林沙漠高大沙山系统的形成

Megadunes, which are at the largest end of scale hierarchies of aeolian bedforms, are extensively developed in major sand seas over the world. However, they remain most poorly studied so that their formation is speculated on unsound scientific evidences. China’s Badain Jaran Sand Sea features the largest megadunes among the world sand seas. What’s more, the unique megadune-lake landscape has attracted interests of researchers from various fields for the last decade. In the philosophy that megadunes and lakes constitute a closely interrelated body, this study, integrating the research from both megadune geomorphology and lake hydrology, intends to, 1) expound the formation mechanism and control factors of meagadunes based on their morphology, development dynamics, sedimentology and macro-patterns; 2) study the atmospheric precipitation-infiltration-storage process in the megadunes, to clarify the supply relationship of the meagadunes to lakes based on meteorological observation at key localities, monitoring and of hydrological analyisis of the water regime in megadunes; 3) reveal the relationship between megadunes and lakes through solving two key problems, the hydrological link between megadunes and lakes, the role of locally driven air circulation by lakes in formation of the megadunes; 4) illuminate formation of the lakes and their supply sources based on the relationship between megadunes and lakes, mutually verify the results of megadune and lake study, thoroughly understand formation mechanism of megadune system in the Badain Jaran Sand Sea.

沙山是尺度最大的沙丘地貌类型，在世界主要沙漠均有发育，但目前几乎没有关于沙山的研究，对其形成的推测一直缺乏科学依据。巴丹吉林沙漠发育世界最高大的沙山，而且具有沙山-湖泊相伴而生的独特景观。近10多年来学者们从不同角度分别关注高大沙山和湖泊问题。本研究将沙山与湖泊视为密切联系的整体，即高大沙山系统，集成沙山地貌学和湖泊水文学两方面的研究，1）通过系统的形态学、演变动态、沉积学以及宏观格局等特征分析，阐明沙山与湖盆的形态-动力学联系。2）通过气象观测、沙山水分监测与水文分析，研究大气降水-沙山入渗-储存过程，结合已有的湖泊水文学研究成果，阐明沙山与湖泊的水文学联系。3）探讨沙山-湖泊系统可能驱动的局地环流在沙山形成中的作用，以及丰富的沉积物来源。实现沙山与湖泊研究互为印证，全面地理解高大沙山系统的形成。

巴丹吉林沙漠发育全世界最高大的沙山，因其具有沙山与湖泊相伴而生的独特地貌景观，长期以来受到学界的高度关注。本研究将沙山与湖泊视为密切联系的整体，通过形态学、沉积学等特征分析，结合气象观测等技术手段，系统地阐述沙山与湖盆的形态-动力学联系，探讨沙山-湖泊系统中可能驱动的局地环流在沙山形成中的作用以及沉积物来源。研究得出：（1）巴丹吉林沙漠作为世界最高大沙山系统的形成机理是以风力作用为主导，即“风成说”，认为高大沙山的维持与沙漠湖泊之间不存在必然的因果关系。基于Lettau和Lettau输沙率公式的双参数Weibull概率分布函数的改进扩展形式可对风环境与风沙活动进行成功评估；（2）基于指纹法的潜在物源区研究显示：高大沙山区的风成沙物源由额济纳戈壁(63.17±21.43%)、黑河(23.15±18.66%)、北大山-雅布赖山山前戈壁(13.68±11.49%)组成；（3）指出巴丹吉林沙漠高大沙山地貌的美学价值研究可将美学原理与风沙地貌学理论结合，潜在价值值得深挖。研究结果有助于进一步全面认识巴丹吉林沙漠高大沙山-湖泊系统的形成，对沙漠旅游等资源的开发利用甚至是行星风沙科学研究亦有一定的借鉴意义。