怒江源区季节冻土短历时冻融事件评价  

Evaluation for short-duration freeze-thaw events of seasonally frozen soil in the headstreams of Nujiang River

作　　者：周炜 翁白莎[2,3] 严登华[2,3] 栾清华[4] ZHOU Wei;WENG Baisha;YAN Denghua;LUAN Qinghua(Hebei Key Laboratory of Intelligent Water Conservancy,Hebei University of Engineering,Handan 056038,China;State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin,China Institute of Water Resources and Hydropower Research(IWHR),Beijing 100038,China;Yinshanbeilu National Field Research Station of Steppe Eco-hydrological System,China Institute of Water Resources and Hydropower Research,Hohhot 010020,China;College of Agricultural Science and Engineering,Hohai University,Nanjing 210098,China)

机构地区：[1]河北工程大学河北省智慧水利重点实验室,河北邯郸056038 [2]中国水利水电科学研究院流域水循环模拟与调控国家重点实验室,北京100038 [3]中国水利水电科学研究院内蒙古阴山北麓草原生态水文国家野外科学观测研究站,呼和浩特010020 [4]河海大学农业科学与工程学院,南京210098

出　　处：《南水北调与水利科技（中英文）》2022年第5期1027-1040,共14页South-to-North Water Transfers and Water Science & Technology

基　　金：国家自然科学基金项目(52022110;51879276);第二次青藏高原综合科学考察研究(2019QZKK0207);中国水科院基本科研业务费项目(MK0145B022021)。

摘　　要：为探究怒江源区季节冻土的冻融特性,选取源区4个典型试验场5 cm表层土壤中发生的短历时冻融事件作为研究对象,明确事件内涵、提出事件具体判别方法并对事件发生的特性进行评价。评价内容由起止时间、总历时、总次数、循环频率、强度共5项组成。其中在强度评价,采用Copula函数法联合温差、湿差、历时3个单一指数构建更全面高效的综合指数,并针对冻结和冻融两个不同的过程分别进行评价。研究表明:怒江源区不同地理位置的短历时冻融事件特性具有差异,中海拔区(4500~5000 m.a.s.l.)的事件比低海拔区(<4500 m.a.s.l.)和高海拔区(>5000 m.a.s.l.)的事件呈现出总历时更长、总次数更多、循环频率更高、累加强度更大的特征规律;高频或高强的事件能够极大影响甚至破环土壤环境,对此更应注重怒江源区北部区域的冻融监测和防护;冻结和冻融是两个强度效应不同的过程,分别评价可避免强度被削弱的问题。研究成果有利于明晰高原寒区季节冻土冻结及融化的特性,进而体现短历时冻融事件的影响,为源区水土保持、冻胀与融塌危害防控提供支撑。Seasonally frozen soil is widely distributed in Qinghai-Tibet Plateau and soil freeze-thaw events occur frequently in the headstream of Nujiang River.Due to the large altitude difference and the asynchrony of meteorological changes between different regions in the headstream region,the occurrence of freeze-thaw events has different characteristics and certain regularities in time and space.To explore the characteristics of freeze-thaw in seasonally frozen soil,the short-duration freeze-thaw events that occurred in the 5 cm surface soil of 4 typical experimental fields of the headstream region were selected.The connotation of the short-duration freeze-thaw events was clarified and a specific identification method for these events was proposed.The characteristics of events were evaluated and the evaluation was formed by five aspects:The start and end time,the total duration,the total number of times,the cycle frequency,and the intensity.In the intensity evaluation,the Copula function method was used to combine three single indexes of temperature difference,humidity difference,and duration to construct a more comprehensive and efficient comprehensive index,and the two different processes of freeze and freeze-thaw are evaluated separately.The evaluation results showed that from September 1,2019,to August 31,2020,the short-duration freeze-thaw events in the 4 typical experimental fields had a maximum difference of 45 days in the start time and 64 days in the end time.The maximum difference in the total duration,the total number of times and the cycle frequency can reach112 days,79 times,and 0.058 times/day,respectively.The maximum difference in the cumulative intensity and the maximum intensity can reach 50.991 and 0.034 for the freezing process,50.991 and 0.034 for the freeze-thaw process.The characteristics of short-duration freeze-thaw events in different geographical locations in the headstream of Nujiang River are different.The events in the middle-altitude area(4500-5000 m.a.s.l.)showed regularity with a longer

关 键 词：季节冻土 冻融事件 COPULA函数 怒江源区 

分 类 号：TV213[水利工程—水文学及水资源] S152[农业科学—土壤学]