变化环境下元江-红河流域径流演变分异及其驱动机制研究

Yuan-Red River, flows through China and Vietnam, is one of the most important international rivers in Southwest China. Under the context of future climate change, the water distribution pattern and water issues faced in Red River will change, which may pose a major threat to water resources supply, ecology security and geopolitical stakes. However, due to little attention paid to Yuan-Red River Basin and absence of an effective theoretical method to treating strongly correlated effect of climate change and hydrological factors, the mechanism of how the runoff varies with climate change and human activities is not yet known. To explore the mechanism of climate change and human activities on runoff.,based on a long series of hydrological and meteorological data, this research select Yuan-Red River Basin as study area and explore the physical mechanism of the runoff to climate factors (precipitation and evaporation) from history to the future with a water simulation method built by a lot hydrological process modeling equations, is focused mainly on the following aspects: (1) the non-parametric Mann–Kendall-Sneyers and Sen’s test is used to identify the trends and change points of the annual runoff with the aim of analysing the changing characteristics of the hydrological cycle. (2) using the combine of Two-parameter climate elasticity index and the analytical derivation of a method which combines six Budyko hypothesis-based water–energy balance equations to separate the effects of climate change and human activities. The Two-parameter climate elasticity index is revisited and enhanced by using the selected function from hydrological process equations in phase (1), then the improved method will be applied to study the elasticity change with temperature and precipitation in the Yuan-Red River basin, whereas to explore the mechanism of the nonlinear response of water resource to climate change. (3) Furthermore, the runoff change and the elasticity of the study area from 2020 to 2050 under representative concentration pathways (RCPs) and water resources use plan will be predicted, also the characters of runoff change under RCPs and water resources use plan will be reveled in this research. The results of the basin studies can establish the relationship between the theoretic study and practical application.

元江-红河是流经我国和越南的国际河流，流域处于纵向岭谷与气候脆弱区，变化情景下水文过程将产生变化，在此背景下研究径流演变的驱动机制是重要的基础课题，是保障地缘利益及跨境水生态安全的内在需求。本项目围绕元江-红河流域径流对气候变化和人类活动的响应分异的驱动机制，以纵向岭谷区不同水热条件及“通道-阻隔”作用下的研究分区为对象，基于近60年来水文、气象资料，利用Mann-Kendall-Sneyers及Sen's等方法，探讨流域径流演变特征及分异规律；构建耦合水热平衡方程与双参数弹性系数法的径流模拟与响应模型，定量评估气候变化驱动径流演变的贡献，进一步分离气候变化和人类活动对径流演变的影响，揭示径流演变及其分异的驱动机制；基于IPCC AR5及未来人类活动组合情景，通过模拟及非线性响应图谱预估径流演变。本项目成果可为全面掌握元江-红河流域径流演变及其分异的原因，防范跨境水安全风险提供科学依据。

变化情景下水文过程将产生变化，使得已揭示的径流演变机理区别于原有规律，并引起水安全问题。元江-红河流域处于西南季风和东南季风交汇地带，受到“通道-阻隔”作用和不同气候条件影响，使得流域径流演变呈现非线性特征，进行径流演变特征识别及其驱动机制的研究具有重要价值。作为我国西南跨境河流，开展元江-红河的径流演变的研究也是防范跨境水冲突的需要。. 本项目通过选取元江-红河流域上下游及干支流代表站进行研究。基于1961-2010年的径流数据，利用Mann–Kendall–Sneyers及滑动t检验法方法探讨径流演变趋势。从径流演变的事实、驱动规律及其时空分异三个层面探讨了元江-红河流域径流对历史和变化情景下的响应分异及其驱动机制。主要进展如下：1.识别元江-红河流域径流、温度、降水等要素的演变趋势及特征，并综合检测了径流演变的线性与非线性特征，辨识历史气候条件下径流演变的关键阶段；2.研究了不同水热条件下径流演变时空分异，探讨了“通道-阻隔”作用下径流演变分异；3.探索了径流过程模拟，构建径流对气候变化响应度量的弹性系数，揭示径流对变化环境下径流非线性响应分异的驱动机制；4.基于非线性响应图谱及IPCC AR5情景数据，预估了未来不同RCPs排放情景下径流演变。本项目的研究提供了径流演变及其分异的机制，可为元江-红河流域水资源保障、跨境生态安全研究提供支撑。本项目的相关成果共计发表论文7篇，培养硕士生4名，完成了预期成果。