基于SHAW模型的黑河上游多年冻土与季节冻土水热过程模拟  

Simulation of water and heat processes of permafrost and seasonally frozen soil in the upper reaches of the Heihe River based on the SHAW model

作　　者：石志峰 李新 孙自永[1] 马瑞[1] 曹斌 SHI Zhifeng;LI Xin;SUN Ziyong;MA Rui;CAO Bin(School of Environmental Studies,China University of Geosciences(Wuhan),Wuhan 430074,China;State Key Laboratory of Tibetan Plateau Earth System,Environment and Resources(TPESER)/National Tibetan Plateau Data Center(TPDC),Institute of Tibetan Plateau Research,Chinese Academy of Sciences,Beijing 100101,China)

机构地区：[1]中国地质大学(武汉)环境学院,湖北武汉430074 [2]中国科学院青藏高原研究所、青藏高原地球系统与资源环境重点实验室/国家青藏高原科学数据中心,北京100101

出　　处：《冰川冻土》2024年第5期1678-1691,共14页Journal of Glaciology and Geocryology

基　　金：国家自然科学基金项目(42102301,41988101)资助。

摘　　要：全球气候变暖导致多年冻土快速升温,并逐渐退化为季节冻土,而多年冻土和季节冻土在土壤稳定性、水分传输及地气交换等方面存在显著差异。因此,探究多年冻土与季节冻土的冻融特征差异具有重要意义。本文基于水热耦合模型(SHAW),以黑河上游祁连山区的大沙龙站(多年冻土)和阿柔站(季节冻土)为研究对象,对土壤温度、湿度和土壤冻融过程进行模拟分析。结果表明:SHAW模型在模拟两种类型冻土站点水热过程时均显示出了良好的精度,在多年冻土站点的总体表现更好。具体而言,多年冻土/季节冻土站点的土壤温度和土壤湿度的平均纳什效率系数(NSE)分别为0.95/0.91和0.74/0.37。同时,两个站点的水热过程差异显著,多年冻土站点模拟期平均冻结速率(6.75 cm·d^(-1))显著大于季节冻土站点(1.33 cm·d^(-1)),而平均融化速率(2.11 cm·d^(-1))略小于季节冻土站点(3.15 cm·d^(-1))。由于多年冻土站点的下伏多年冻土层起着“地下冷源”的作用,深层(80 cm以下)土壤温度的季节波动幅度小于季节冻土站点。本文结论可为研究黑河上游多年冻土与季节冻土的冻融差异提供参考。Global climate warming causes permafrost to rapidly heat up and gradually degrade into seasonally frozen soil.There are significant differences between permafrost and seasonally frozen soil in terms of soil stabil⁃ity,water transport,and land-atmosphere interaction.Distinguishing between permafrost and seasonally frozen soil is essential due to their distinct hydrothermal dynamics,freeze-thaw behaviors,and sensitivities to climatic variables.This study is based on the coupled hydrothermal model(Simultaneous Heat and Water model,SHAW),taking Dashalong Station(permafrost)and Arou Station(seasonally frozen soil)in the Qilian Moun⁃tains in the upper reaches of the Heihe River as the research objects,to simulate soil temperature,moisture and soil freezing and thawing processes.The results show that the SHAW model exhibits great accuracy in simulat⁃ing hydrothermal processes at both types of frozen soil sites,but its overall performance is better at permafrost sites.Specifically,the average Nash efficiency coefficients of soil temperature and soil moisture at permafrost/seasonally frozen soil sites are 0.95/0.91 and 0.74/0.37.These findings underscore the SHAW model’s height⁃ened efficacy in simulating permafrost environments,particularly evident in its more accurate representation of soil temperature dynamics.The mean biases in the simulation of soil temperature and soil moisture at permafrost and seasonally frozen soil stations were determined to be 0.56/-1.40℃,and-0.001/0.03 m³·m⁻³,respective⁃ly.Further examination of simulations pertaining to active layer thickness and the duration of ground surface freezing revealed relatively higher errors at permafrost station.Conversely,errors were comparatively minimal at permafrost station,evidenced by an average depth error of the active layer thickness of merely 10.6 cm and an average error rate of 3%,affirming the SHAW model’s high precision in permafrost station simulations.Con⁃versely,seasonally frozen soil station demonstrated superior performance

关 键 词：多年冻土 季节冻土 SHAW 土壤温度 土壤湿度 冻融循环 

分 类 号：P642.14[天文地球—工程地质学]