气候变化非稳态下黄土高原植被恢复对水文干旱的影响机制

The Loess Plateau is a very important region for the Belt and Road Initiative and the Western Development Strategy of China. Drought is considered to be one of the most harmful nature disasters in this area and has greatly affected socio-economic sustainable development. Under the impact of global warming and enhanced human activity, the assumption of the stationarity of the streamflow series is no longer hold and the results of streamflow drought by traditional frequency analysis would become doubtful, this also makes the relationship between drought and the changes in the vegetation more complicated. Therefore, the research on the assessment of drought considering the nonstationarity and estimate its response to changing environment becomes an important scientific problem to guarantee the water, food and ecosystem security in the Loess Plateau. In this study, the Loess Plateau is selected as a study area to analyze the relationship between the vegetation restoration and the changes in hydrological drought. Firstly, the spatial and temporal changes of the vegetation restoration as well as the hydrological and climatic variables in the Loess Plateau are investigated. Secondly, a time-variant hydrological drought index considering the nonstationarity of the changing environment is developed to analyze the variability of drought in the study area. Then, distributed hydrological model is constructed with the consideration of vegetation restoration to reveal the impact of climate and vegetation condition on the changes of hydrological drought. Finally, the drought risk is estimated under different climate and vegetation scenarios. The results of this project can provide scientific and technological basis for the scientific assessment and decision-making management of drought disaster in the Loess Plateau and also other areas in China.

黄土高原是国家“一带一路”和“西部大开发”的前沿阵地，干旱是影响该地区社会经济可持续发展最严重的自然灾害之一。近年来，黄土高原植被恢复显著，改变了流域水文过程，破坏了水文干旱分析的稳态性假设前提，加剧了植被恢复对干旱影响的复杂性和不确定性。开展气候变化非稳态下黄土高原植被恢复对干旱影响机理研究已成为保障该地区水资源安全和生态安全迫切需要解决的重要科学问题。本项目以黄土高原为研究对象，系统分析近三十年来黄土高原植被恢复格局和变化特征，发展气候变化非稳态条件下的水文干旱评估方法，通过野外监测、构建分布式水文模型和不同植被恢复情景下的水文干旱分析，阐明水文干旱对气候变化和植被恢复的敏感程度，揭示黄土高原植被恢复对水文干旱的影响机理，综合预估不同气候变化和植被恢复情景下水文干旱发生风险。项目成果可为流域水资源管理、防灾减灾和社会经济可持续发展等提供技术支撑，同时为黄土高原地区生态环境建设提供参考。

黄土高原是国家“一带一路”和“西部大开发”的前沿阵地，干旱是影响该地区社会经济可持续发展最严重的自然灾害之一。近年来，黄土高原植被恢复显著，改变了流域水文过程，加剧了植被恢复对干旱影响的复杂性和不确定性。开展气候变化非平稳下黄土高原植被恢复对干旱影响机理研究已成为保障该地区水资源安全和生态安全迫切需要解决的重要科学问题。.针对上述问题，项目组经过4年的协同研究，取得的主要成果有： .（1）系统分析了近三十年来黄土高原植被恢复格局和变化特征。1982-2015年间，黄土高原干湿状况变化不显著，植被状况整体趋于改善。黄土高原绝大部分区域SPEI、SPI与NDVI的正相关性均较为显著。.（2）发展了气候变化非平稳条件下的水文干旱评估方法。基于GAMLSS框架，选择与径流密切相关的气候指数刻画气候变化影响，构建了非平稳标准化径流指数（NSRI），该指数能较好地刻画黄土高原地区水文干旱变化，与实际旱情较为吻合。20世纪90年代的黄土高原水文干旱情况均较为严重。.（3）定量评估了气候变化和植被恢复对水文干旱的贡献。基于VIC模型和不同气候变化及植被恢复情景，发现气候变化是导致水文干旱平均干旱强度发生变化的主要原因（植被恢复贡献占比为4.97%），人类活动是导致水文干旱平均历时发生变化的主要原因（植被恢复贡献占比为21.25%）。.（4）综合预估了不同气候变化和植被恢复情景下水文干旱变化。2023-2100年黄土高原地区径流整体呈现上升趋势，退耕还草和退耕还林情景下的水文干旱发生频次在大多数流域均呈现减少的趋势，但是平均干旱历时和强度均有不同程度的增加。.本项目有助于理解变化环境下黄土高原植被恢复水文效应，揭示植被生态系统与水文过程的相互作用机制，对区域的水资源管理、抗旱减灾规划和社会经济可持续发展等提供支撑。.项目组共在国内外学术期刊发表学术论文13篇，其中SCI收录8篇，中文核心论文5篇，授权发明专利1项，培养研究生5名，获齐鲁水利科技一等奖1项。