IMHE OpenIR  > 山地表生过程与生态调控重点实验室
冻融作用对长江源区土壤水文过程的影响与模拟
Alternative TitleEffects of freezing and thawing on soil hydrological process in the source area of Yangtze river and simulation
朱美壮
Subtype硕士
Thesis Advisor王根绪
2018
Degree Grantor中国科学院大学
Place of Conferral北京
Degree Discipline自然地理学
Keyword青藏高原 多年冻土区 土壤入渗 冻融过程 水热过程
Abstract全球气候变暖的事实毋庸置疑。近年来,长江源区降水呈显著增加趋势同时长江源区气温的升高也导致了下垫面性质发生重大变化,冰冻圈变化将会对山区水资源变化带来巨大影响,对我国水安全有着重要的影响,同时也对江河源区生态环境恢复和陆面过程等影响深远。因此,急需定量评估冰冻圈对未来气候变化的响应,从而为制定水资源可持续利用对策提供理论基础。因此,本论文依托于长江源区风火山小流域,研究了气候变化背景下,冻土和植被覆盖变化对土壤水文过程的影响,基于实测参数将研究区扩展至整个长江源区,并采用VIC(Variable infiltration capacity)模型对整个长江源区蒸散发和土壤水热过程进行了模拟。主要得到的结果有:1. 不同植被盖度下土壤入渗特征差异明显,在活动层融化阶段,多年冻土区土壤水分入渗与非冻土区入渗特征一致,入渗性能均随植被盖度的降低而减小;而在开始冻结和开始融化阶段,由于受到多年冻土区复杂的水热过程影响而出现分异。不同坡位土壤水分入渗特征具有显著的坡位差异并于冻融过程相关联,但总体特征变化基本一致,高坡位相比低坡位具有更好的入渗性能。通过三种典型的入渗模型拟合分析,得出模型的适用性受土壤空间位置、植被覆盖和冻融过程综合影响,不同情境下适用性优劣不同。2. 对影响土壤入渗的环境因子进行分析,得出多年冻土区相比非冻土区具有其独特性,主要体现在活动层融化阶段,主导入渗性能的环境因子与非冻土区相似,皆为土壤理化性质、土壤性状以及植被覆盖等因素。而在开始融化与开始冻结阶段,土壤理化性质及结构对入渗性能的影响微弱,主导因子为土壤温度和土壤水分。3. 整个坡面上,浅层土壤温度与气温具有显著的正相关关系;随着坡位的增高,土壤温度对气温的响应越加强烈,当土壤深度>50 cm之后,二者相关性逐渐减弱。水热耦合模型 在不同坡位土壤温度与水分具有较好的模拟效果。4. 多年冻土区蒸散发过程受冻融过程显著影响。年尺度上最大蒸散阶段出现在融化阶段,雨热同季;冻结阶段,降水减少,受热量过程影响,土壤冻结,水分发生相变,该阶段蒸散发量锐减;蒸散发与气温、光合有效辐射、地表热通量、表层5 cm和根系层20 cm土壤温度显著正相关。对年际尺度和不同冻融阶段蒸散发与环境因子进行逐步回归,得出不同阶段环境因子与蒸散发量的回归方程。5.基于VIC模型对长江源区表层土壤水热过程和蒸散发进行模拟。结果表明VIC模型对长江源区表层土壤水热过程与蒸散发均具有较大的纳什效率系数,1999-2016年空间尺度上,表层土壤水分和土壤温度均呈现出自东南向西北递减的规律;蒸散发总体趋势自东南向西北递减,最低值出现在长江源腹地。这主要是在全球气候变化背景下,增温、降水增加及潜在蒸散综合作用的影响。
Other AbstractThere is no doubt that the global warming is a fact. In recent years, precipitation in the source region of the Yangtze River has increased significantly. At the same time, the increasing of temperature in the source region of the Yangtze River has also led to significant changes in the feature of the underlying surface. Changes in the cryosphere will have a huge impact on the water resources changes in the mountains, and will contribute to China’s water security. It also has a profound impact on the ecological environment restoration and land surface processes in the source regions of the rivers. Therefore, it is urgently needed to quantitatively evaluate the response of the cryosphere to future climate change, so as to provide a theoretical basis for formulating countermeasures for the sustainable utilization of water resources.Therefore, this paper choose the Fenghuo Mountain watershed in the source region of the Yangtze River to study the impact of frozen soil and vegetation cover changes on the soil hydrological process under climate change. The study area is extended to the entire source area of the Yangtze River based on measured parameters and the VIC is used. . The model has simulated the evapotranspiration and soil hydrothermal processes in the source region of the Yangtze River. The main results are as follows:1. The characteristics of soil infiltration under different vegetation coverages are significantly different. In the thawing stage of active layer, soil water infiltration in permafrost regions is consistent with infiltration characteristics in non-frozen areas, and infiltration performance decreases as the coverage of vegetation decreases. And in the beginning of the freeze and the beginning of the thawing phase, due to the complex hydrothermal processes in the permafrost region, the differentiation occurs. Soil water infiltration characteristics at different slope positions have significant differences in slope position and are associated with freeze-thaw processes, but the overall characteristic changes are basically the same, and the high slope position has better infiltration performance than the low slope position.Through the infiltration analysis of three typical infiltration models, the applicability of the model is affected by the spatial location of the soil, the vegetation cover and the freeze-thaw process. The applicability is different in different situations.2. By analyzing the environmental factors that affect soil infiltration, it is concluded that the permafrost region is unique compared to the non-frozen regions. This is mainly reflected in the fact that the environmental factors affecting the infiltration performance in the thawing stage of the active layer are similar to those in the non-frozen regions, and all of these factors are the physical and chemical properties of the soil, soil properties, and vegetation coverage. While at the beginning of melting and the beginning of the freezing stage, the soil physical and chemical properties and structure have little effect on infiltration performance, and the dominant factors are soil temperature and soil moisture.3. On the whole slope, there is a significant positive correlation between the temperature of the shallow soil and the air temperature; with the elevating of the slope position, the response of the soil temperature to the air temperature becomes more and more intense. When the soil depth is more than 50 cm, the correlation between the two decreases gradually. . The hydrothermal coupling model has good simulation effect on soil temperature and moisture at different slope positions.4. The process of evapotranspiration in permafrost regions is significantly affected by freezing and thawing processes. On the annual scale, the maximum evapotranspiration stage occurs in the thawing phase, and the rain and heat are in the same season; in the refreezing stage, the precipitation is reduced, and the soil is frozen due to the heat process, and the water changes phase, and the evapotranspiration decreases sharply during this stage; evapotranspiration and temperature, photosynthesis There was a significant positive correlation between evapotranspiration and temperature, photosynthetically active radiation, surface heat flux, temperature of surface layer 5 cm and soil temperature of root layer 20 cm. The evapotranspiration and environmental factors in the interannual scale and different freeze-thaw stages were gradually regressed, and the regression equations of environmental factors and evapotranspiration were obtained at different stages.5. Based on the VIC model, the surface soil moisture and evapotranspiration in the source region of the Yangtze River were simulated. The results show that the VIC model has a large Nash efficiency coefficient for surface soil moisture and evapotranspiration in the source region of the Yangtze River. From 1999 to 2016, the surface soil moisture and soil temperature showed a decreasing law from southeast to northwest; evapotranspiration, the general trend of hair growth decreased from southeast to northwest, and the lowest value appeared in the hinterland of the Yangtze River. This is mainly due to the effects of warming, increased precipitation, and potential evapotranspiration in the context of global climate change. 
Pages106
Language中文
Document Type学位论文
Identifierhttp://ir.imde.ac.cn/handle/131551/24759
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
First Author Affilication中国科学院水利部成都山地灾害与环境研究所
Recommended Citation
GB/T 7714
朱美壮. 冻融作用对长江源区土壤水文过程的影响与模拟[D]. 北京. 中国科学院大学,2018.
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