三江源河湖沉积物的风沙侵蚀及生态修复研究

A huge amount of river and lake deposits have been stored in Sanjiangyuan region during geomorphic processes. The deposit was covered with herbaceous vegetation after the plateau uplift. Due to global climate change and human activities the vegetation has been scarred with sand dunes recently. Desertification has become a serious threat to ecological environment. Therefore, research on desertification control and ecological restoration has important scientific and practical significance for ecological environment restoration in Sanjiangyuan region. Alpine environment in Sanjiangyuan region is unique, the main shortage of previous studies are threefold: 1)study area was limited; 2)quantitative research was less and innovative research methods were lack; 3)mechanism research was less. We plan to carry out a systematic field survey in typical river-lake deposits and eolian sand deposits in Sanjiangyuan region. The inner mechanism and relevant measures in desertification control and ecological restoration are planned to be further studied. Based on the new theory of vegetation-erosion dynamics, a predicting model is planned to be established to evaluate the ecological status and evolution tendency of desertification area. The contents of this study are threefold: 1) mechanism and features of eolian sand erosion process of river-lake deposits; 2) key factors and effective measures of desertification control and ecological restoration; 3) evaluation model of ecological status and evolution tendency of desertification area. The results can provide quantitative scientific basis for desertification management and ecological restoration in Sanjiangyuan region. Moreover, research ideas and methods of this project can provide technical supports for desertification control and ecological management of other desertification areas.

三江源区沉积了巨量河湖沉积物，随高原抬升后地表发育了脆弱的植被系统，在全球气候变化和人类活动影响下，这一区域正面临严重的风沙侵蚀和土地沙漠化威胁，区域生态环境趋于退化。开展沙漠化控制及生态修复关键问题研究对三江源区生态环境恢复具有重要的科学和现实意义。三江源区高寒环境特殊，相关研究工作存在不足：1）研究区域局限；2）定量研究少，缺乏创新性研究手段；3）微观机理研究较少。本项目拟以三江源区河流沉积物和风沙沉积物为研究对象，深入定量研究河流沉积物沙漠化控制和生态修复的内在机理及相关措施，引入植被-侵蚀动力学学科的创新理论建立沙漠化区生态评估模型。主要内容包括：1）河湖沉积物的风沙侵蚀机理和过程研究；2）三江源沙漠化控制和生态修复的内在因素及措施；3）沙漠化区生态现状及趋势的评估模型。项目研究成果可为三江源区沙漠化治理和生态恢复提供科学依据，其研究方法可为沙漠化治理和生态管理研究提供技术支持。

三江源区沙漠化控制及生态修复问题研究对流域生态环境修复具有重要的科学意义。三江源区属于高寒气候条件，生态环境脆弱，沙漠化生态修复工作特殊。针对高寒地区沙漠化治理和生态修复工作，本项目深入开展了多方面定量研究。研究了风沙侵蚀过程引起的颗粒级配和矿物颗粒组成的变化特征，结果表明，经过风沙侵蚀的分选作用，颗粒均匀，矿物成分以石英为主，可作为风沙沉积物的鉴定特征。研究了不同沙漠化程度区沙颗粒含量与沙漠化程度的定量关系，提出了适用于三江源地区的沙漠化风险指数。以活动沙丘迎风坡（≈15º）为实验对象，开展了高原野外风洞试验，分析了沙丘迎风坡风沙输移特征，研究了植被措施对风沙侵蚀的控制方法。对典型高寒沙漠化生态治理区的活动沙丘、半固定沙丘和固定风沙土开展了采样分析工作，研究了活动沙丘固定过程中泥沙颗粒组成、矿物成分以及养分变化规律变化特征，讨论了生物结皮层在沙丘固定与生态修复中的重要作用，分析了高寒条件下人工植被措施对沙漠化控制与生态修复的效果。以植被覆盖度与风沙侵蚀量为表征量，并将影响植被和风沙活动的人为应力作为独立方程项，建立了植被风沙侵蚀动力学模型。并成功应用于黄河源木格滩沙漠化区，分析了植被风沙侵蚀动力学特征，模拟和预测植被与风沙侵蚀的演变规律，对该区域的治理和生态修复提供了建议。

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