Water Science and Environmental Engineering Research Center, College of Chemical and Environmental Engineering, Shenzhen University, Shenzhen 518060, China.
Space Intelligence and Informatics Research Center, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518060, China.
Sci Total Environ. 2020 Jun 1;719:137507. doi: 10.1016/j.scitotenv.2020.137507. Epub 2020 Feb 22.
Reference evapotranspiration (ETo) is the basic component of the hydrological cycle. This study systematically analyzed the spatiotemporal variations of ETo in the Three-River Headwaters Region (TRHR) by utilizing the FAO Penman-Monteith equation during the period of 1961-2016, and studied the impact of climatic variables on ETo fluctuation based on sensitivity analysis and contribution analysis. Over the past 56 years, ETo increased in most months and annually in most regions of the TRHR, and the spatial distribution for annual ETo varied apparently. Sensitivity analysis revealed that ETo responded more to changes in maximum temperature and sunshine duration than relative humidity, wind speed, and minimum temperature. The relative importance of climatic variables to ETo was influenced by the ETo sensitivity and the fluctuation of climatic variables. Contribution analysis indicated that the significant temperature increase was mainly responsible for the observed increase in ETo. Besides, spatially distributed analysis showed that the annual TRHR ETo tended to increase from east to west, north to south, and high to low elevation. The analysis also indicated a dominant altitudinal spatial gradient in the sensitivity of ETo to changes in different climatic variables. The physical mechanisms for ETo variations discussed in this study might provide a reference for water resources management and conservation of high-elevation areas.
参考蒸散量（ETo）是水文循环的基本组成部分。本研究利用 1961-2016 年期间的 FAO Penman-Monteith 方程，系统地分析了三江源地区（TRHR）的 ETo 时空变化，并基于敏感性分析和贡献分析研究了气候变量对 ETo 波动的影响。在过去的 56 年中，TRHR 大部分地区的 ETo 在大多数月份和全年都呈增加趋势，年 ETo 的空间分布明显不同。敏感性分析表明，ETo 对最高温度和日照时间的变化比相对湿度、风速和最低温度更敏感。气候变量对 ETo 的相对重要性受到 ETo 敏感性和气候变量波动的影响。贡献分析表明，显著的温度升高是导致 ETo 观测增加的主要原因。此外，空间分布分析表明，TRHR 的年 ETo 倾向于从东向西、从北向南、从高海拔向低海拔增加。该分析还表明，ETo 对不同气候变量变化的敏感性存在主导的海拔空间梯度。本研究讨论的 ETo 变化的物理机制可能为水资源管理和高海拔地区的保护提供参考。
