IMHE OpenIR
川西高山区地表蒸散发遥感估算研究
Alternative TitleEstimation of Surface Evapotranspiration by Remote Sensing Method in Mountain Area of Western Sichuan
黄盼
Subtype硕士
Thesis Advisor李爱农 ; 赵伟
2017
Degree Grantor中国科学院大学
Place of Conferral北京
Degree Discipline地图学与地理信息系统
Keyword地表蒸散发 遥感 SEBS模型 地形影响 山区
Abstract作为陆地生态系统水文循环过程中最重要的水分输出机制,地表蒸散发与地表水热平衡息息相关。然而,在山地特殊的气候和地形条件下,山地地表蒸散过程表现出极大的复杂性及地形相关性。本研究选取川西山区为研究区域,以Landsat 8影像为遥感数据源,并且结合DEM数据考虑了山区的地形影响,反演得到蒸散估算所需的地表特征参数(如植被结构参数、地表温度、地表反照率和山区地表入射太阳辐射等),之后基于SEBS模型框架估算出研究区的地表水热通量,并瞬时蒸散通过积分关系法拓展到日尺度。最后分析了研究区不同下垫面的蒸散特征,并对日蒸散和地表参数、地形因子的关系进行了探讨,得到如下结论:(1)基于站点观测数据的验证,太阳辐射估算结果平均绝对误差为48.5 W·m-2,平均相对误差为6%,精度较高,可以满足下一步估算水热通量的要求;至于日蒸散发的验证,本研究利用站点常规气象数据,基于 Penman-Monteith 公式计算得到参考蒸散量并根据站点周围下垫面类型乘以相应的作物系数,然后与估算ET相比,在亚高山观测站和磨西基地的相对误差分别为9.5%和9.1%。(2)地表蒸散空间分布存在明显差异,且在不同下垫面的分布特征也有所不同。从总体上看,在植被覆盖低的地方其值越低,在中部和西南部高原地区由于缺乏水分,甚至可达零值,随着植被覆盖的提高,蒸散变大,其中在植被覆盖区又表现出阴阳坡差异,阳坡的蒸散大于阴坡,这与阳坡接收到更多的太阳辐射有关。研究区主要土地覆被类型的平均日蒸散发量从大到小依次是林地>冰川雪地>水体>人工表面>耕地>灌丛>草地。(3)本研究对日蒸散与NDVI和地表温度的关系进行了拟合,通过分析发现,蒸散量与NDVI和地表温度分别呈二次函数和反S型曲线关系,拟合系数分别为0.91和0.99,可见日蒸散的大小与NDVI和地表温度息息相关。因此,当缺乏气象观测数据时或者对估算结果的精度要求不高,可以利用NDVI或地表温度与蒸散的经验关系来求取日蒸散。 (4)在山区,受地形因子的影响,山地自然环境随海拔升高而出现垂直分带的现象,因此导致山地地表蒸散表现出一定的地形相关性。在1000m-1600m之间,随海拔的升高日蒸散迅速的减少,因为该区段处于东南丘陵进入高山峡谷区的过渡带,地形遮蔽现象开始出现,太阳辐射逐渐减小,进而导致日蒸散在该区域呈减小趋势;在1600m-2600m之间,植被覆盖度高而且水分充足,蒸散主要由热力条件决定,而在该区段内太阳辐射随海拔上升逐渐增加,因此蒸散量也随海拔上升而增大;在2600m-5000m之间,日蒸散随海拔的上升先减小再增大,这种变化趋势主要与山地垂直分带现象有关,因为随着海拔上升,土地覆被类型由森林向灌丛、草地、冰川雪地过渡,而研究区内林地、灌丛、草地和冰川雪地的日蒸散平均值分别为3.89、3.03、2.66、3.80,所以该区段内的日蒸散随海拔上升先减小后增大。
Other Abstracts the most important water output mechanisms in the hydrological cycle of terrestrial ecosystems, surface evapotranspiration is closely related to the surface water heat balance. However, under the special climate and terrain conditions, the process of mountain surface evapotranspiration shows great complexity and terrain correlation. In this study, the mountain area of Western Sichuan was selected as the research area, and the Landsat image was used as the remote sensing data source. With the aid of DEM, the land surface parameters (vegetation structure parameters, land surface temperature, albedo and mountain surface solar radiation, etc.) were retrieved. Then these parameters were input into the SEBS model to estimate the surface water heat flux and daily evaporation. Finally, the spatial distribution characteristics of daily evaporation in the study area were analyzed, and the relationship between daily evaporation and surface parameters was discussed. The conclusions were as follows: (1) Based on the validation of the site observation data, the average absolute error of solar radiation estimation was 48.5 W·m-2 and the average relative error is 6%, the accuracy was high. As for the validation of daily evapotranspiration, the reference evapotranspiration was calculated by using the conventional meteorological data from the site, according to the Penman-Monteith formula. Compared with the estimated ET, the relative errors of the sub Alpine stations and Moxi bases were 9.5% and 9.1%, respectively.(2) There were significant differences in the spatial distribution of surface evapotranspiration, and the evapotranspiration was different under different land cover. In the middle and southwest plateau area with low vegetation coverage, Evapotranspiration can reach zero value because of lacking of water. With the increase of vegetation coverage, evapotranspiration became larger. In addition, the evapotranspiration value also showed the slope difference that the value of sunny slope was greater than the shady slope. The average daily evapotranspiration of different land cover in the study area was from large to small: Woodland, bare surface, water, artificial surface, cultivated land, shrub, grassland (3) In this study, the relationship between daily evapotranspiration and NDVI\ surface temperature was fitted, and the fitting coefficients were 0.91 and 0.99, respectively. It can be seen that the daily evapotranspiration is closely related to NDVI and surface temperature. Therefore, NDVI and surface temperature can be used as an important indicator of daily evapotranspiration. When the demand of precision is not high, the daily evapotranspiration can be estimated by the empirical relation between them. (4)Due to the phenomenon of vertical zonation, the surface evapotranspiration of mountain area showed terrain correlation. In 1000m-1600m, the daily evapotranspiration decreased rapidly with the increase of altitude. Because the phenomenon of the terrain shading was serious in the range, the solar radiation decreased gradually, which resulted in a decreasing trend of daily evapotranspiration in this range. In 1600m-2600m, the vegetation coverage was high and the water was abundant. The evapotranspiration was mainly determined by the thermal condition, and the solar radiation increases with the height increasing, so the evapotranspiration increases with the height increasing. In 2600m-5000m, the daily evapotranspiration firstly decreased and then increased with the increase of altitude, which was mainly related to the vertical zonation. The types of land cover changed from forest to shrub, grassland, glacier and snow which the daily evapotranspiration of forest, shrub, grassland and glacier snow was 3.89, 3.03, 2.66 and 3.80, respectively, so the evapotranspiration firstly decreasd and then increased with the increase of altitude. 
Pages85
Language中文
Document Type学位论文
Identifierhttp://ir.imde.ac.cn/handle/131551/24569
Collection中国科学院水利部成都山地灾害与环境研究所
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
黄盼. 川西高山区地表蒸散发遥感估算研究[D]. 北京. 中国科学院大学,2017.
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