Beijing Key Laboratory of Urban Hydrological Cycle and Sponge City Technology, College of Water Sciences, Beijing Normal University, Beijing, 100875, China.
Beijing Key Laboratory of Urban Hydrological Cycle and Sponge City Technology, College of Water Sciences, Beijing Normal University, Beijing, 100875, China.
Environ Res. 2022 Sep;212(Pt B):113275. doi: 10.1016/j.envres.2022.113275. Epub 2022 Apr 15.
Evapotranspiration (ET) is a critical variable in the world's water cycle, and plays a significant role in estimating the impact of environmental change on the regional hydrothermal cycle. Moreover, as an essential of eco-hydrological processes, changes in ET may exceptionally impact the local climate and provide indicative information on the eco-system's functioning. The Hailar River Basin (HRB), located in northern China, is one of the most sensitive areas to climate warming. Under the influence of climate change in recent years, the vegetation dynamics of the basin have been significant and have had profound effects on the regional water cycle conditions and hydrological processes. The HRB is located in a semiarid region and ET is the main mode of water consumption. The ET response to climate change and vegetation dynamics is the focus of research on ecohydrological processes in this basin. In this study, a distributed hydrological model, the BTOPMC model, is used to evaluate the actual ET in the HRB from 1981 to 2020, based on in situ meteorological data as well as LAI data obtained by satellite remote sensing. The seasonal, interannual and spatial dynamics of ET were characterized. The contribution of meteorological factors to ET was calculated by sensitivity analysis and multiple linear regression analysis, and the predominant elements influencing the difference in ET in the HRB were also discussed. The results show that: (1) estimated ET values can clarify over 85% of the seasonal variation in the observed values (R= 0.79, P < 0.001; R= 0.84, P < 0.001), which demonstrates that the model has a high precision. (2) Over the past 40 years, the annual ET has shown a clear increasing trend and a large spatial heterogeneity in its spatial distribution, which is consistent with the trend of vegetation. It mainly shows that the eastern forest area is larger than the central forest-grass transition area and the western meadow steppe area. (3) Sensitivity and influential factor contribution analyses show that the main factor driving interannual variability in ET is climate warming, followed by precipitation. At the same time, vegetation dynamics also play a crucial role in ET, especially in areas with different vegetation types and high coverage, while climatic factors also have a strong influence on ET indirectly through vegetation. Due to its special geographic location, the HRB is more sensitive to global climate change and is a typical ecologically fragile area. Therefore, this study has important scientific value and social significance for maintaining ecological security and the sustainable use of water resources.
蒸散量（ET）是全球水循环中的一个关键变量，在估计环境变化对区域热水平衡的影响方面起着重要作用。此外，作为生态水文过程的重要组成部分，蒸散量的变化可能会对当地气候产生特殊影响，并提供有关生态系统功能的指示信息。海拉尔河流域（HRB）位于中国北部，是对气候变暖最敏感的地区之一。在近年来气候变化的影响下，流域植被动态变化显著，对区域水循环条件和水文过程产生了深远影响。HRB 位于半干旱地区，蒸散量是主要的耗水方式。蒸散量对气候变化和植被动态的响应是研究该流域生态水文过程的重点。本研究采用分布式水文模型 BTOPMC 模型，利用实测气象数据和卫星遥感获取的叶面积指数（LAI）数据，对 1981 年至 2020 年 HRB 的实际蒸散量进行评估。分析了蒸散量的季节性、年际和空间动态。通过敏感性分析和多元线性回归分析计算了气象因素对蒸散量的贡献，并讨论了影响 HRB 蒸散量差异的主要因素。结果表明：（1）估算的蒸散量值可以很好地解释观测值的 85%以上的季节性变化（R=0.79，P<0.001；R=0.84，P<0.001），表明模型具有较高的精度。（2）过去 40 年来，年蒸散量呈明显增加趋势，其空间分布具有较大的空间异质性，与植被变化趋势一致。主要表现为东部林区大于中部林草交错区和西部草甸草原区。（3）敏感性和影响因素贡献分析表明，驱动蒸散量年际变化的主要因素是气候变暖，其次是降水。同时，植被动态对蒸散量也起着至关重要的作用，特别是在植被类型和覆盖度不同的地区，而气候因素通过植被对蒸散量也有很强的间接影响。由于其特殊的地理位置，HRB 对全球气候变化更为敏感，是典型的生态脆弱区。因此，本研究对于维护生态安全和水资源的可持续利用具有重要的科学价值和社会意义。
