多年冻土活动层土壤水分相变过程观测及模拟研究

In the process of freezing-thawing cycle in permafrost active layer, the phase change of soil moisture is the core research of the law of water and heat movenment.For cold regions hydrology,the plateau's ecological environment, the regional climate evolution and construction projects,this research are of great significance. The research of the hydrothermal parameters of phase change of soil moisture in the permafrost active layer is still stuck in the theoretical analysis and empirical knowledge. There is considerable controversy at some theory and parameterization schemes, and thus it was not sufficient to establish permafrost water-heat coupling mode based on the physical mechanisml. With the breakthrough of the key monitoring technology in recent years,the study of the phase change process of soil moisture in permafrost active layer can be further explorated. This project is based on the State Key Laboratoryof Frozen Soil Engineering and the Tanggula Dongkemadi Glacier-permafrost observation stations. Breakthrough of observation technology (differential heat pulse scanning and pF-meter) can be used for laboratory tests and field observations in typical permafrost zone. Through the experiment, we can obtain the unfrozen water content, ice content and soil water potential. By analyzing the law of the phase change and hydrothermal migration, we can study the relations and influence mechanism of the water-thermal parameters of soil moisture in active layer, and then improve water and heat transport parameterization scheme in soil freezing-thawing process. Finally, based on the field observation data in Tanggula Dongkemadi station, the improvement of the frozen soil parameterization scheme will be verified. These studies can lay the foundation for the study of the response between permafrost active layer and climate change.

多年冻土活动层冻融循环中水热运移规律核心内容水分相变规律研究对于寒区水文、高原生态环境、区域气候演变及工程建设均具有重要意义。活动层土壤水分相变等关键水热参数的研究还停留在理论分析和经验认识上，甚至有些理论和参数化方案存在巨大争议，因而对于支持冻土中水热耦合模型的构建还不够充分。随着近几年关键观测技术的突破，活动层土壤水分相变过程的观测研究可以开展进一步的探索研究。本项目依托冻土工程国家重点实验室和唐古拉冬克玛底冰川冻土观测站，在室内针对不同类型土壤、在野外典型冻土区，利用突破发展的观测技术（差热式脉冲扫描和pF-meter）获取未冻水含量、含冰量及土壤水势，分析水分相变及水热运移规律。研究活动层土壤水热参数的相互关系和影响机制，进而探讨改进细化土壤冻融过程的水热运移参数化方案。最终，基于唐古拉冬克玛底的野外观测数据，验证改进的冻土参数化方案，为研究多年冻土活动层对气候变化的响应奠定基础。