| 题名 | 长江源多年冻土区流域能量与水量平衡过程研究 |
| 作者 | 刘光生 |
| 学位类别 | 博士 |
| 答辩日期 | 2012-05-22 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 王根绪 |
| 关键词 | 长江源 多年冻土 水循环 水热过程 GEOtop模型 |
| 其他题名 | The Water and Energy Balance of Permafrost Watershed in the Headwater Region of Yangtze River |
| 学位专业 | 自然地理学 |
| 中文摘要 | 由于长江源区对气候变化敏感性，使其成为气候变化的水文水资源响应的热点研究区域之一。植被变化和冻土退化对流域水文过程将产生何种影响，其中气候-植被-冻土-水循环的相互关系是其核心科学问题。本论文得到的研究成果如下： 1. 三江源区气温普遍显著升高，而降水的增加并不显著，年径流尤其是夏秋季节径流呈现明显减小的趋势。三江源区径流过程对气温变化较降水变化更为敏感。随着多年冻土的退化，长江源区径流减少的趋势将进一步加剧。 2. 河水氢氧同位素的季节变化和空间差异是与壤中流、地下水补给河流的季节差异和植被覆盖的空间差异有关。随着地温升高和土壤冻融锋面的迁移，河水补给来源和同位素特征发生改变，表明土壤冻融变化对多年冻土流域径流过程起到重要作用。植被盖度及其驱动的冻融过程的差异，改变了径流组成。 3. 随着植被盖度降低，高寒草甸不同深度土壤开始融化和冻结时间均不断提前，地温变化速率增大，对气温的响应程度增高。高盖度植被有利于土壤维持水分，及维持活动层土壤水热状况的稳定性，起到保护多年冻土的作用。 4. GEOtop模型能准确模拟高寒生态系统多年冻土活动层的水热传输过程，对多年冻土区小流域的径流过程也进行较好的刻画。 |
| 英文摘要 | Due to the great sensitivity to climate change sensitivity in source area, make it a hot climate change research area. Furthermore, the influence of vegetation changes and the frozen soil degradation on hydrological processes is almost unknown, and the relationships between climate, vegetation, permafrost and water cycle are the key scientific problems. The results are as follows: 1. The TRHR has experienced a persistent and pronounced warming and a statistically non-significant increase in precipitation. However, a decrease in runoff and runoff coefficient was found. Permafrost plays a significant buffering role in runoff reduction caused by climate warming. The descending trend of the runoff coefficient suggests that basin storage and the mechanism of runoff generation may have changed appreciably. 2. The temporal-spatial distribution of stable isotopes for river water was influenced by the seasonality variation of river recharge from soil water and underground water and spatial difference of vegetation coverage. Along with the migration of freeze-thaw front of active soil layer, the source of river water and the variation characteristics of stable isotopes for river water changed. This suggests that the freeze-thaw of active soil layer plays an important role in rainfall-runoff process in permafrost watershed. 3. As vegetation cover in the alpine swamp decreased, the soil water thaw-rise time and the soil water freeze-fall time occurred slower. Low vegetation covers are also linked to higher thermal diffusivity and thermal conductivity in the soils. AThe maintenance of a high vegetation cover on alpine meadow and swamp meadow reduces the impact of heat cycling on the permafrost, may minimize the impact of climate change and helps preserve the microenvironment of the soil. 4. The GEOtop model shows promising performance in simulating hydrological processes in cold regions. The simulated hydrograph is in good agreement with in situ observations. This model can be applied to improve our understanding of the hydrological processes in cold regions and to assess the impacts of global warming on hydrological cycles and water resources. |
| 语种 | 中文 |
| 公开日期 | 2013-01-15 |
| 内容类型 | 学位论文 |
| 源URL | [http://192.168.143.20:8080/handle/131551/4811]  |
| 专题 | 成都山地灾害与环境研究所_山地表生过程与生态调控重点实验室 |
| 推荐引用方式 GB/T 7714 | 刘光生. 长江源多年冻土区流域能量与水量平衡过程研究[D]. 北京. 中国科学院研究生院. 2012. |
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