黄土高原流域水沙变化研究进展

人类活动和气候变化是影响流域水文过程的两大驱动因素,径流输沙是流域水文过程的总体反映,变化环境下径流输沙的变化规律与成因分析是水文学和全球变化研究的热点问题。黄土高原是我国水土流失最严重的地区。20世纪50年代以来,黄土高原地区开展了大规模的生态环境建设和水土流失综合治理,显著改变了流域土地利用和植被覆盖。下垫面条件改变与气候变化综合作用,使得流域水沙情势发生剧变。围绕黄土高原流域水沙变化的时空尺度特征与驱动机制,总结了径流输沙和水沙关系变化特征的研究结果,归纳了径流输沙变化的归因分析方法与人类活动和气候变化影响的贡献分割结果,探讨了气候变化、植被恢复、水土保持工程措施以及流域景观格局对水沙变化的影响机制。未来应加强流域水沙演变的时空尺度特征特别是水沙关系非线性特征的定量研究,阐明极端事件对水沙动态的影响与贡献;开展水沙变化影响机制的多要素综合解析,发展耦合地表覆被动态特征和气候变化的降雨-径流-输沙模型,揭示生态恢复与水沙演变过程互馈机制;开展未来气候变化、社会经济发展和生态建设工程情景下水沙动态的趋势预测,为黄土高原生态综合治理和水资源管理与黄河水沙调控提供策略建议。

Changes in streamflow and sediment load in the catchments of the Loess Plateau, China: a review

Human activities and climate change are two critical driving forces of catchment hydrological processes, for which, streamflow and sediment load are the two main indicators. Changing trends and attribution analysis of streamflow and sediment load under changing environments are now the focus of hydrological and global change studies. The Loess Plateau (LP) of China is well known for its severe soil erosion and the heavy sediment load of the Yellow River that flows through it. To control soil erosion in the LP, large ecological restoration construction projects and several soil and water conservation measures have been implemented since the 1950s, which have resulted in extensive land use and vegetation cover changes. These extensive changes in land surface conditions in combination with climate change have dramatically altered the hydrological regime, including streamflow, sediment load, and flow-sediment relationships in the LP. The spatio-temporal variability of streamflow and sediment load, and the dominant mechanisms behind these changes are important issues in the development of strategies for sustainable land and water management in the LP. We reviewed previous studies that documented changes in streamflow, sediment load, and flow-sediment relationships to improve our understanding of these processes. The methods used to separate the impacts of human activities and climate change on streamflow and sediment load and the results obtained in these studies are summarized here. The influence of climate change, vegetation restoration, soil and water conservation measures, as well as catchment landscape patterns on driving changes in streamflow and sediment load are also discussed. Finally, the following further studies are proposed:1) Studying the spatio-temporal patterns in streamflow and sediment load evolution and quantifying the non-linear characteristics of flow-sediment relationships, 2) Demonstrating the effects and contributions of extreme events on streamflow and sediment load dynamics, 3) Conducting comprehensive analyses on the influence of multiple factors on streamflow and sediment load, 4) Developing a coupled rainfall-streamflow-sediment yield model that includes the dynamic characteristics of surface cover and climate change, with the aim of revealing feedback mechanisms between ecological restoration and the evolution of streamflow and sediment load, and 5) Predicting streamflow and sediment load dynamics under future scenarios of climate change, with the added effects of socio-economic development and ecological construction engineering; which is likely to provide suggestions for ecological treatment and water resource management in the LP, and regulation of water and sediment in the Yellow River.