青藏高原坡面冻土土壤水分空间变异特性  

Spatial variability of permafrost soil-moisture on the slope of the Qinghai-Tibet Plateau

作　　者：曹伟[1,2] 盛煜[1] 吴吉春[1] 李静[1] 王生廷 

机构地区：[1]中国科学院西北生态环境资源研究院冻土工程国家重点实验室,甘肃兰州730000 [2]重庆市国土资源和房屋勘测规划院,重庆400020

出　　处：《水科学进展》2017年第1期32-40,共9页Advances in Water Science

基　　金：中国科学院重点部署项目(KZZD-EW-13);中国博士后科学基金资助项目(2016T90962)~~

摘　　要：为深入揭示坡面冻土水分运移规律及其主要影响因子,以青藏高原巴颜喀拉山北坡为例,结合冻融变化过程,研究不同地形条件冻土土壤水分空间变异特征,利用分类回归树模型(CART)和典范对应分析(CCA)识别影响坡面冻土土壤水分空间异质性的主控因子及其相互作用关系。研究结果表明:1受坡面地形与冻融过程影响,冻结期坡面冻土土壤水分侧向流动减弱,以垂直迁移为主,上坡位含量高于下坡位,反之,融化期上坡位含量则低于下坡位。2影响坡面冻土土壤水分的主要环境因子为高程、土壤质地、土壤温度和植被覆盖度,但在不同冻融阶段下其影响因子存在差异,在冻结状态下主要因子为高程、土壤质地和土壤温度,其相对贡献率分别达到19.97%、19.45%和9.56%;在融化阶段下主要因子为高程、植被覆盖度和土壤质地,其相对贡献率分别为37.4%、14.9%和10.7%。3 0~20 cm浅层深度上影响坡面冻土土壤水分的主要因素为坡度、高程和植被覆盖度,其相关系数分别高达0.941 2、0.903 9和0.563 1;中下层深度上其主要影响因素较为复杂。Permafrost degradation and its freezing-thawing process affect the physical, chemical and biological processes of ecological and hydrological systems in cold regions. In particular, the movement of water in frozen soil is the most important carrier or the main form of migration-transformation of matter and energy in each surface layer in cold regions. Thus, the movement of water in frozen soil is one of the primary forces driving water-resources deterioration and ecological-function degradation. One of the key problems is to reveal the spatial and temporal variability of soil moisture movement and its main controlling factors in permafrost regions. In the Qinghai-Tibet Plateau, the occurrence of permafrost is complex due to different terrain features. Therefore, the spatial variability of the permafrost soil-mois- ture is more significant. Thus, we explore the spatial variability and its main controlling factors of permafrost soil-mois- ture on the northern-slope of the Bayan Har Mountains in the Qinghai-Tibet Plateau. The method of classification and regression tree （CART） is adopted to identify the main controlling factors influencing the soil moisture movement. Ad- ditionally, the relationships between soil moisture and environmental factors are revealed by the use of canonical correspondence analysis （CCA）. The results show the following： ① This greatly enhances the horizontal flow in the freezing period due to the terrain slope and the freezing-thawing process. Vertical migration is the main form of soil moisture movement, and it causes the soil-moisture content in the up-slope to be higher than that in the down-slope. In con- trast, the soil-moisture content in the up-slope is lower than that in the down-slope during the melting period. ② The main environmental factors that affect the slope-permafrost soil-moisture are elevation, soil texture, soil temperature and vegetation coverage. However, there are differences in the impact factors of the soil moisture in different freezingthawing stages.

关 键 词：青藏高原 坡面尺度 多年冻土 土壤水分 空间变异特征 

分 类 号：P642.14[天文地球—工程地质学]