黄河源区多年冻土活动层厚度空间分异特征研究

cold regions ecology,hydrological cycles and permafrost environments in the Sources Areas of the Yellow River (SAYR) had changed dramatically under the warming climate conditions during the past decades.Influenced noticeably by the spatial distribution of permafrost,hydrothermal processes and depth variations of the active layer,the eco-environmental changes present regional differences. To research the regional characteristics,mechanisms and trends of eco-environmental changes, the study of spatiotemporal differentiations of active layer thickness should be carried out attentively.This project takes warm permafrost in the SAYR as an object to study, single sites at Maduo Town, a site at north bank of the Gyaring Lake,Tangchama at south of the Ng?ring Lake,and Chalaping for monitoring soil temperature and moisture content will be taken as regional sites.Furthermore,fifteen regular grids in three different scales for long-term monitoring of dynamics of active layer thickness will be set up in shady and sunny slopes of Chalaping, where the active layer thickness generally less than 1.5 m. The active layer thickness will be determined as maximum seasonal penetration of the 0 ℃ isotherm for single regional sites. As for those regular grid sites, geophysical exploration, steel probings and pit probings in the middle autumn will be used to determine the active layer thickness.Then the differentiation and autocorrelation of active layer thickness will be studied based on geostatistical methods in different spatial scales, namely "regional" (>100,000 m), "meso" (1,000 ~ 100,000 m), local (100 ~ 1000 m) and micro (0.10 ~ 100 m) scales.What's more,microreliefs,vegetations,soil thermal properties,textures and moisture content will be investigated simultaneously among the monitoring sites.Then the spatial correlations of the active layer thickness with microreliefs, vegetations,soil thermal properties, soil moisture content and textures will be studied by means of multivariate statistical methods. Based on above studies, taking air temperature,soil temperature and moisture,and soil thermal properties as driving forces,the active layer thickness will be modelled by Stefan equation,the Geophysical Institute Permafrost Lab (GIPL) model, and heat transfer model.Hence the influence mechanisms of spatial differentiation of active layer thickness will be studied. The results will provide key parameters for accurate regional mapping of permafrost and active layer thickness,and the theoretical basics to the study of responses of eco-environmental degradations to climate warming in the SAYR.

气候变暖条件下，寒区生态、水文循环、多年冻土环境等发生了显著改变，要深入探讨寒区环境变化机制及其趋势就需开展活动层厚度空间分异特征的研究。为此，本项目以黄河源高温冻土区为研究区，主要开展以下3个方面的研究工作：（1）在麻多乡、扎陵湖南、鄂陵湖北岸及查拉坪一带布设单点式、规则格网单元式长期定位监测场地，结合温度和水分插值、物探、钎探和坑探，基于空间统计方法研究区域、中、局地和微尺度上活动层厚度的空间分异特征；（2）在监测场地开展植被、微地貌和土壤热物理性质的调查，基于空间相关方法和多元统计方法研究活动层厚度空间分异的影响因素；（3）在上述工作基础上，以气温、土壤热物理性质等作为驱动，利用Stefan经验公式、GIPL模型和热传输模型深入研究活动层厚度的空间分异机理。研究结果可为大范围多年冻土和活动层厚度的精准制图提供参数支持，并为揭示黄河源区生态环境对气候变化的响应机制提供理论依据。

气候变暖条件下，寒区生态、水文循环、多年冻土环境等发生了显著改变，要深入探讨寒区环境变化机制及趋势就需开展活动层厚度空间分异特征的研究。为此，本项目以黄河源高温冻土区为研究区，主要开展以下5个方面的研究工作：1）、在黄河源区查拉坪、汤岔玛、哈日穷谷地等开展活动层厚度的钎探、冻土物探及地面温度监测工作，建设半定位式活动层厚度监测场地；2）、结合环北极活动层厚度监测计划（CALM）200多个监测点的活动层厚度、海拔、经纬度及相关环境要素的描述，较为全面地分析了北半球活动层厚度的时空变化特征及其影响因素；3）、结合国家基准台站气温、地面温度数据，分析了冷极端温度指数，冻融指数及其与活动层厚度的相关关系；4）基于Kudryatsev方法，模拟了黄河源区近30年来活动层厚度和温度、多年冻土面积时空变化特征；5）、基于黄河源区查拉坪、汤岔玛双岔沟及鄂陵湖、麻多乡等场地温度和水分数据，分析了黄河源区多年冻土活动层和季节冻土冻融时空特征。相关研究将为黄河源区寒区生态和水文变化提供重要科学依据。