KMS XINJIANG INSTITUTE OF ECOLOGY AND GEOGRAPHY，CAS
| 荒漠河岸林区地下水、植被及蒸散的组合关系 | |
| Alternative Title | Combined Relationships between Groundwater, Vegetation and Evapotranspiration in Desert riparian forest areas |
| 孙海涛 | |
| Subtype | 硕士 |
| Thesis Advisor | 陈亚鹏 |
| 2019-06-30 | |
| Degree Grantor | 中国科学院大学 |
| Place of Conferral | 北京 |
| Degree Discipline | 理学硕士 |
| Keyword | 荒漠河岸林植被 地下水波动 生态系统 蒸散发 塔里木河下游流域 Desert riparian forest vegetations Ecosystems Evapotranspiration Lower reaches of the Tarim River |
| Abstract | 在干旱地区，地下水蒸散发（ETg）是区域水分和能量平衡的重要组成部分，影响着干旱区的地表生态过程和地下水文过程。地下水不仅是许多水生生态系统，而且也是干旱和半干旱地区陆生植物的重要水源，尤其是在依赖于地下水的生态系统，植被所需的水分部分或全部来源于地下水。 在干旱荒漠区， 地下水蒸散发过程十分复杂， 它是由地下水—植被—蒸散发综合作用的结果， 受植被的物候期、河流的侧向补给作用、地下水位埋深、和气象因素（太阳辐射、 气温等） 等多种因素的影响， 并在时间和空间上对地下水蒸散过程产生十分重要的影响。 因此，在塔里木河下游开展地下水、植被及蒸散发相互关系的研究， 对区域地下水资源的管理、可持续利用以及荒漠河岸植被的恢复和保护都具有重要意义。本研究通过对塔里木河下游典型荒漠河岸林胡杨群落、柽柳群落和胡杨＋柽柳群落等 4 处观测点地下水位的监测，植物样地的调查，以及植被相关指数（盖度、 Simpson 多样性指数、 Pielou 均匀度等） 和地下水蒸散发 ETg的计算， 分析了地下水位和地下水蒸散发的时空变化特征及其影响因素，探讨了地下水位， 植被与地下水蒸散发间的相互关系。 得出以下主要结论：（1）塔里木河下游地下水位的变化在 7-10 月份分为两个明显不同的阶段。在 8月 12日生态输水之前，由于荒漠植物对地下水的利用导致水位呈下降趋势；而随着 8 月份的生态输水，在河水的侧向补给作用下，地下水位逐渐抬升。并且在 4 个观测点都存在明显的地下水位昼夜波动现象。随着地下水位埋深的增加，各植被指数呈现出先增后减的变化趋势，且在 3 米左右植被盖度和多样性指数明显减少。（2）利用 Loheide 方法估算出 4 个观测点的地下水蒸散发 ETg，发现 4 个观测点地下水蒸散发在日尺度上表现为单峰状态，即 ETg在早晨 8点开始快速增加，并在 12:00~16:00 之间维持在一个较高水平上，在 18:00 以后快速下降。从生长盛期到落叶期，地下水蒸散发呈逐渐减小的趋势，表明 ETg 的季节变化与植被的物候有关。（3）在整个观测期内，四个观测点的地下水蒸散发分别为 2.51、 3.12、 3.19和 1.89 mm/d。空间上，地下水蒸散发 ETg 植被类型、盖度的不同而存在显著差异，同时又受地下水位埋深的影响。太阳辐射是影响塔里木河下游 ETg 的主要因素，且同时受气温和饱和水气压差的控制，降水对 ETg 有一定的影响，风速对其无显著影响。（4）对比不同观测点地下水、和植被盖度与地下水蒸散发的关系发现， ETg随着水位的下降而减小，并且随着水位下降植被盖度也在减小，表明在空间上水位下降对 ETg 的影响其实是由于水位下降引起植被减少而造成的。通过对同一观测点 ETg 与地下水位关系变化发现，在 C6、 D2 和 G5 处， ETg 与地下水位呈正相关关系，即 ETg 随着水位的下降而增加，这可能是由于当水位下降时，胡杨和柽柳可能会吸收更多的地下水以应对干旱环境而导致的。 |
| Other Abstract | In arid regions, groundwater evapotranspiration (ETg) is an important componentof regional water and energy balance, affecting the surface ecological processes andgroundwater processes. Groundwater is not only an important aquatic ecosystem, butalso an important source of terrestrial plants in arid and semi-arid areas, especially inecosystems that rely on groundwater. Some or all of the water needed for vegetationcomes from groundwater. In the arid desert regions, the process of groundwaterevapotranspiration is very complex. It is the result of the combined action ofgroundwater-vegetation-evapotranspiration, the phenological period of vegetation, thelateral recharge of rivers, the depth of groundwater level, and meteorological factors(solar radiation). The influence of various factors, such as temperature, etc., has asignificant impact on the groundwater evapotranspiration process in time and space.Therefore, the explore of the relationship between groundwater, vegetation andevapotranspiration in the lower reaches of the Tarim River is of great significance forthe management and sustainable use of regional groundwater resources and therestoration and protection of desert riparian vegetation.This study adopted the monitoring of groundwater level at four observation sitesof Populus euphratica community, Tamarix chinensis community and Populuseuphratica + Tamarix community in the typical desert riparian forest in the lowerreaches of the Tarim River, survey of plant plots, and vegetation related index(coverage, Simpson diversity index, Pielou uniformity ), and other calculations of ETgin groundwater evapotranspiration, analysis of the spatial and temporal variationcharacteristics of groundwater level and groundwater evapotranspiration and itsinfluencing factors, and the relationships between groundwater level, vegetation andgroundwater evapotranspiration. The following main conclusions are drawn:(1) The change in groundwater level in the lower reaches of the Tarim River isdivided into two distinct phases from July to October. Before the ecological watertransport on August 12, the water level showed a downward trend due to the use ofgroundwater by desert plants. With the ecological water transport in August, thegroundwater level gradually rose under the lateral recharge of river water, and thereare obvious diurnal water table fluctuations in the four observation sites. With theincrease of the buried depth of the groundwater level, the vegetation index showed atrend of increasing first and then decreasing, and the vegetation coverage and diversity index decreased significantly at about 3 meters.(2) Loheide method was used to estimate the ETg of groundwaterevapotranspiration at four observation sites, and it was found that the ETg ofgroundwater evapotranspiration at four observation sites presented a single-peak stateon the daily scale, that is, ETg began to increase rapidly at 8:00in the morning, andmaintained at a high level between 12:00 and 16:00, and decreased rapidly after 18:00.From the growth peak to the deciduous stage, the evapotranspiration of groundwatershows a gradually decreasing trend, indicating that the seasonal change of ETg isrelated to the phenology of vegetation.(3) During the whole observation period, the groundwater evapotranspiration atthe four observation sites was 2.51, 3.12, 3.19 and 1.89mm /d, respectively. Spatially,there are significant differences in ETg vegetation types and coverage of groundwaterevapotranspiration, which are also affected by the depth of groundwater table. Solarradiation is the main factor affecting ETg in the lower reaches of Tarim River.Meanwhile, under the control of air temperature and saturated water pressuredifference, precipitation has a certain influence on ETg, while wind speed has nosignificant influence on it.(4) By comparing the relationships between groundwater, vegetation coverageand groundwater evapotranspiration at different observation sites, it is found that ETgdecreases with the decreasing of water level, and vegetation coverage decreases withthe decreasing of water level too, indicating that the effect of water level drop on ETgis actually caused by the decrease of vegetation caused by water level drop. Throughthe change of the relationship between ETg and groundwater level at the sameobservation site, it is found that ETg is positively correlated with groundwater level atC6, D2 and G5, that is, ETg increases with the decrease of water level, which may befollowed by the fact that Populus euphrates and Tamarix chinensis may absorb moregroundwater to cope with the drought environment when the water level drops. |
| Subject Area | 自然地理学 |
| Language | 中文 |
| Document Type | 学位论文 |
| Identifier | http://ir.xjlas.org/handle/365004/15331 |
| Collection | 中国科学院新疆生态与地理研究所 研究系统 |
| Affiliation | 中国科学院新疆生态与地理研究所 |
| First Author Affilication | 中国科学院新疆生态与地理研究所 |
| Recommended Citation GB/T 7714 | 孙海涛. 荒漠河岸林区地下水、植被及蒸散的组合关系[D]. 北京. 中国科学院大学,2019. |
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