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青海省共和盆地沙漠化驱动机制
李晓英1,2, 姚正毅1, 董治宝1
1.中国科学院 西北生态环境资源研究院, 甘肃 兰州 730000;2.中国科学院大学, 北京 100049
摘要:
[目的] 研究青海省共和盆地沙漠化的形成和发展过程,探讨沙漠化形成机制,为共和盆地生态环境治理提供科学依据。[方法] 利用Google Earth和ArcGIS分析不同区域的沙漠化分布特征;通过6期遥感卫星影像解译比对,对沙丘移动速度和古沙丘活化速度进行监测;并利用SPSS对共和盆地气温、降水、风速和牲畜数量进行分析;结合野外调查、实验室粒度分析、地层分析,研究沙漠化的形成过程。[结果] 共和盆地流动沙片分布广泛,发育有大量雅丹地貌,沙漠化土地呈斑块状、条带状交错分布。地层分析显示,固定沙丘的表层覆盖有厚度不一的粉沙土,其下为松散古风成沙。土地沙漠化的主要形式是固定沙丘活化、河湖相细沙外露、固定沙带及古沙丘活化。[结论] 有胶结作用的粉沙土是古风成沙的保护层,而食草动物的践踏是破坏保护层的主要原因。在动物破坏、风沙流及重力侵蚀作用下,粉沙土层崩塌破坏,更多古风成沙暴露,此过程循环往复,造成沙丘活化,形成风蚀坑,是共和县沙漠化形成和发展的主要过程。
关键词:  共和盆地  沙漠化  驱动机制  固定沙丘活化
DOI:10.13961/j.cnki.stbctb.2018.06.051
分类号:
基金项目:国家重大科学研究计划项目“青藏高原沙漠化对全球变化的响应”(2013CB956000)
Driving Mechanism of Aeolian Desertification in Gonghe Basin of Qinghai Province
LI Xiaoying1,2, YAO Zhengyi1, DONG Zhibao1
1.Northwest Institute of Eco-environment and Resources, Chinese Academy of Sciences, Lanzhou, Gansu 730000, China;2.University of Chinese Academy of Sciences, Beijing 100049, China
Abstract:
[Objective] The objective of this paper was to analyze the causes and processes of aeolian desertification in Gonghe basin of Qinghai Province, and to provide scientific basis for controlling the ecological environment.[Methods] Google Earth and ArcGIS were used to analyze the distribution characteristics of aeolian desertification in different regions. The movement velocity of sand dunes and the velocity reactivation of fossil dunes were monitored by comparing the interpreted remote-sensing images in six periods. The temperature, precipitation, wind speed, and livestock number were analyzed by the SPSS. In addition, the formation process of aeolian desertification was studied according to the field investigation, grain-size test, and analysis of stratigraphy.[Results] The mobile dunes and sand sheets are widely distributed in Gonghe basin of Qinghai Province. There have a large number of aeolian Yardang landforms, and the sandy lands are interlaced with patch and strip. Stratigraphic analysis showed that the surface of fixed dunes is covered by sandy silt with different thickness, and the layer under there is relatively loose sand. The main forms of aeolian desertification are the reactivation of fixed sand dunes, the exposure of fine sands from rivers and lakes, and the reactivation of fixed sand belts and fossil dunes.[Conclusion] Cemented silts layer is a protective shell of the loose sand, and trampling of grazing animals is main reason for the damage of this protective layer. Under trampling of grazing animals damage, sand flow, and gravity erosion, the collapse and destruction of the silts layer lead more loose sand exposed. The circulation of this process made the reactivation of fixed sand dunes and formed the blowouts, which is the main process of aeolian desertification formation and development in the Gonghe Basin of Qinghai Province.
Key words:  Gonghe basin of Qinghai Province  aeolian desertification  driving mechanism  reactivation of fixed sand dunes