IMHE OpenIR  > 山地表生过程与生态调控重点实验室
贡嘎山季节性冻土与积雪的水文效应及其模拟研究
Alternative TitleModeling Research on the Hydrological Effects of Seasonal Soil-frozen and Snow-cover in Gongga Mountain
Language中文
李卫朋
Thesis Advisor程根伟
2015
Degree Grantor中国科学院研究生院
Place of Conferral北京
Degree Name博士
Degree Discipline自然地理学
Keyword贡嘎山 积雪冻土 冻融过程 水文效应 数学模拟
Abstract贡嘎山高山环境在青藏高原东缘和西南地区具有典型性和代表性,其山地冰川和森林对水文过程的影响机理十分复杂,这方面已经有大量的研究工作。高寒山区也是冰雪冻土分布的主要区域,“气候变化背景下,季节性冻土和积雪变化趋势有什么特点,对气候变化的响应是否比其它要素更为敏感?季节性冻土和积雪变化对该区域山地水循环要素的影响程度如何?”这些科学问题亟需解答,然而该地区环境空间异质性强且缺少观测资料,这是上述科学问题探究的难点。 为研究季节性冻土、积雪对山地水文过程的影响,揭示季节性冻土-积雪影响降雨径流形成机制,本文基于贡嘎山东坡3000气象站及黄崩溜沟典型小流域的气象水文观测资料,采用回归分析、趋势分析等统计方法,结合分布式水文模型技术,研究了季节性积雪、冻土冻融转换过程中水热变化特点及其对流域水文过程的影响,分析了降水、气温、地温、径流量、地下水位、积雪厚度、冻土深度等气象水文要素之间的统计关系及其变化趋势;重点探讨了土壤冻结的平均起止时间,无冻结日数及其对气温变化的响应;以降水、气温作为主要输入数据,通过分布式山地水文模型模拟了该流域径流及其融雪、融冰产流以及地下水位等重要输出变量。主要研究结果如下。 1.近20年来贡嘎山海螺沟地区气温整体呈显著上升趋势。平均气温为5~10℃上下,最高气温在20~25℃之间,最低气温在-20~-10℃之间,平均气温与最低气温均呈增加态势,显示气候变化对该地区低温影响明显。平均地温为8℃上下,也呈上升趋势。而地温最高温在40 ℃上下波动,且有下降趋势;最低低温在-20℃~0℃之间,总体上地温比气温变幅显著,地温增幅大于气温,地-气温差呈轻微上升趋势。平均气温与平均地温呈现显著的线性相关关系,为通过气温推算地温提供了前提。 2.近20年来贡嘎山海螺沟地区降水无显著变化,但在1998年前后出现了显著的峰值,高达2175mm,其中积雪在1997年年累计厚度达到最大(271cm)。20年内积雪整体上略有下降趋势。黄崩溜沟最大日径流在1998年前后达到峰值。日最小流量比较平稳,显示了该地区有稳定的地下水基流。日平均径流与日最大径流量变化态势的差异反映了降水年内分配的不均匀性。最大雪深与最大降水量变化趋势基本接近。季节性冻土最大冻结深度下限受降水和最低气温影响在1996年前后出现了显著的峰值(1997年以后没有观测记录)。海螺沟3000m地下水位与降水、径流的峰值基本上呈现较好地对应关系,即降水量丰沛的夏季,洪峰出现的时候地下水位埋深(从地面向下的距离)变浅,冬季少雨季,径流深降至全年谷值时,地下水埋深也达到全年最深值,但有一定时滞。 3.月均气温和地温进行统计分析,发现均存在良好的线性关系。平均截距为3.15,即低温比气温高3.15℃,这为用气温推算土壤冻结的温度阈值提供了一定参考。对气温、降水、雪深进行分析,发现强降雪的次年基本上伴随着强降水。本文提出一种冻融指示参数,其分布形态与冻土深度变化具有较好的对应关系,同时可以反映冻土观测是否有有明显数据缺失或异常数据;研究发现季节性积雪量和冻土量变化与气温变化相比都存在一定时滞,且有缓冻速融的特征。积雪与积温模比系数变化趋势基本一致,冻土深度在达到峰值之前,有一个较为稳定的持续积累期,冻土深度与积温模比系数在冻土深度峰值之后一致性显著增强。这为基于温度等指标进行积极性积雪、冻土的冻结与融冰、融雪产流模拟提供了依据。 4.1988-2004年间开始冻结日期在9月中下旬至11月初,分布相对分散,终止融化日期在4月中下旬至5月中旬,分布较为集中。总体而言,下半年开始冻结(始冻)日总体推后,上半年融化结束(终融)日整体提前,无冻日数整体上与气温升高相一致,呈上升趋势。1990-2004年间,冻融日数平均值为196天,开始冻结日期平均每年推后3.1天,终止冻结日期平均每年提前2.8天,无冻日平均每年增加5.9天。1998年气温为观测时段内最高,年均温达5.4 ℃,冻融指示参数FS表明1998年春季融化终止日比1997年和1998年分别提前了15天、18天,而其秋季开始冻结日期分别比1997年和1998年滞后了39天、23天,无冻期分别比1997、1999年长了52天、39天。 5.分析冻融周期的土壤温度随时间和深度变化的等值线图,发现0℃等温线与实测冻土深度趋势大致一致,但冻土下限变化比土壤温度变化更为平缓,且其对土壤温度的响应具有一定的时滞。15日滑动平均值与等0℃等温线有很好的对应关系,并由此确定土壤冻结下限变化滞后于0℃等温线变化约15天。 6. 限于有限的输入数据(通常只能得到降水、气温等常规气象资料),对积雪、冻土水文效应模拟主要采用一种准三维(垂向上分三层)的概念性流域水文模型来实现。该模型在水平面上将流域划分成矩形单元栅格,纵向上划分出植被、土壤与地下水库层,其中上层包气带土壤分为上、中、下层。对于每个网格单元,分别进行植物截留、蒸散发、土壤水分计算。对于下层饱和带——浅层地下水和和深层渗漏补给,按统一的地下水库计算蓄泄水量及潜水位变化。最后,输出各网格单元和流域总体的径流量、蒸散发、地面积雪厚度、冻土深度以及地下水位。通过该模型反映森林植被、积雪、冻土对水水文过程(入渗、产流和蒸散发)的影响,对积雪与冻土调蓄作用下林地径流特征进行动态模拟。其中积雪、冻土模拟主要采用度日因子法。 7.采用上述流域水文模型对黄崩溜沟1995-2000年的日径流进行模拟,结果表明模型对于径流过程和冻土积雪变化都能给出较好的结果,其中洪峰出现时间模拟整体较好,春季径流模拟略微有所偏高。模型初步模拟的ENS=0.97,均方差MSE=2.14,相关系数r=0.80, 确定性系数R2=0.87,结果比较理想。对其他目标变量进行检验,发现,模拟水位与观测水位间的确定性系数为0.75,而积雪、冻土模拟变化趋势基本相同,模拟结果比较满意。 8.贡嘎山3000米站所在区域全年大致可划分5~10月的无季节性冻土、积雪期,11~次年4月季节性冻土、积雪覆盖期,其中季节性冻土集中出现在12月~次年3月。10月正积温为144.7℃,负积温仅为0.9℃,尚不足以使得土壤冻结,但短时低温期有极少量的积雪,其水当量仅为径流深(125mm)的1%;11月,负积温增加至22.5℃,正积温降至43.3℃;1月正积温为0℃,负积温与积温均为-100.9 ℃,表明1月份处于持续冻结积累期;2月份负积温增至全年最大值102.9℃,冻土水当量比重增至25%,积雪比重也增至49%;2月~3月份,气温开始回升,正负积温此消彼长,逐渐出现日冻融循环,但先是冻大于融,而后逐渐反转过来,至4月中上旬,季节性积雪、冻土基本完成消融。多年平均状态下,季节性积雪和冻土对该区域河川径流的平均组分贡献率分别为16%、17%。这一比例还将会随着气温的升高发生改变,并显著地影响当地的水文过程特征。 上述研究结果可以为深入理解、评估该区域季节性冻土-积雪的冻融过程及其对河川径流的影响提供科学依据。
Other AbstractGongga Mountain is one of the typical mountain in the region of the eastern Tibet Plateau and the Hengduan mountain area of Southwestern China, the hydrologic processes of which are complex for the glaciers, forests, seasonal frozen soil, seasonal snow cover, etc. For glaciers and forests, there have been a wide variety of classic work done by many prominent scientists at home and abroad. While, for seasonal frozen soil, seasonal snow cover, even sometimes maybe mentioned as a certain aspect or section, it is rarely to see any systematic study within the area, especially, on the hydrologic effects of the seasonal frozen soil and snow cover. Then,“What will happen to the seasonal frozen soil and snow cover under rapid changing environment, how sensitive and in what way will the two response to the climate change? what are their hydrologic effects on the hydrologic elements and processes, such as precipitation style, forests-shrubs-meadows interception, evapotranspiration and infiltration from the crown canopy-meadows or snow cover/frozen soil, and runoff? to what extent?” The fractured, heterogeneous and patch structure cold alpine environment make it challengeable besides the freezing-thaw machenism itself. In order to identify the hydrologic effects of seasonal frozen soil and seasonal snow cover, to reveal the underlying mechanism, lots of work in the dissertation based on series routine observations and gauged data at the 3000 m weather station, Alpine Ecosystem Observation and Experiment Station of Gongga Mountain was done with statistical and distributed simulation method; to yield some major insights into the water and heat rises, declines, trade-off of seasonal frozen soil-snow cover with seasonal shifts, the associated effects on hydrologic cycles, and the trend and relationships among the hydro-meteorological elements were also revealed. At the same time, the start date, end date and the duration of seasonal soil freezing were detected to show its response to climate change. At last, the melt water from the seasonal snow and frozen soil was simulated and compared with the total runoff to show their contribution among the runoff fractions. The mainly results are shown as follows. 1. In the late two decades (1988~2010), the temperature increased in the whole. The maximum air temperature decreased slightly between 20~25℃; the average air temperature increased between 5~10℃. The minimum air temperature(-20℃~0℃) increased more under the warming climate. The maximum ground temperature fluctuated around 40 ℃; while the minimum ground temperature(-20℃~0℃) increased more obviously under the warming climate;the ground temperature showed an overall more obvious change than that of air temperature. The good linear relationship between the air temperature and the ground temperature make it possible to estimate the ground temperature. 2.The precipitation in the region varied without obviously tendency in the late two decades (1988~2010). The precipitation got a peak of 2175mm around 1998, while the snow showed a slight decrease with a peak of 271 cm in 1997. The maximum daily runoff climbed to its peak around 1998 too.While, the minimum daily runoff was steady for the base flow; the seasonal frozen soil got a peak around 1996(It has been lack of frozen soil observation since 1998). The ground water level has a well response to precipitation and runoff well in the whole but with little lags. 3. The monthly averaged air temperature shown a well linear relation with that of ground temperature in the whole with an averaged intercept of 3.15℃, which offered references to estimate the freezing point. Based the ground temperature 0℃, a freezing-thaw detected index FS was proposed, the distribution pattern of which has a fine correspondence to the frozen depth. Both of the seasonal snow and frozen soil has a time lag to response to the temperature variation. The module ratio of snow and minus accumulated temperature shown similar tend
Document Type学位论文
Identifierhttp://ir.imde.ac.cn/handle/131551/15064
Collection山地表生过程与生态调控重点实验室
Affiliation中国科学院成都山地灾害与环境研究所
Recommended Citation
GB/T 7714
李卫朋. 贡嘎山季节性冻土与积雪的水文效应及其模拟研究[D]. 北京. 中国科学院研究生院,2015.
Files in This Item:
File Name/Size DocType Version Access License
贡嘎山季节性冻土与积雪的水文效应及其模拟(9103KB)学位论文 开放获取CC BY-NC-SAView Application Full Text
Related Services
Recommend this item
Bookmark
Usage statistics
Export to Endnote
Google Scholar
Similar articles in Google Scholar
[李卫朋]'s Articles
Baidu academic
Similar articles in Baidu academic
[李卫朋]'s Articles
Bing Scholar
Similar articles in Bing Scholar
[李卫朋]'s Articles
Terms of Use
No data!
Social Bookmark/Share
File name: 贡嘎山季节性冻土与积雪的水文效应及其模拟研究.pdf
Format: Adobe PDF
All comments (0)
No comment.
 

Items in the repository are protected by copyright, with all rights reserved, unless otherwise indicated.