黄河上中游草地退化和退耕还林的区域气候水分效应

黄河上中游地跨半干旱和半湿润气候带，是流域最主要的产水、输沙和耗水区，也是对气候变化最敏感的区域之一。近年来，黄河源区草地退化和上中游的退耕还林显著地改变了流域的植被覆盖，是导致黄河流域径流减少、土壤变干的重要因素，但由于未能准确描述植被变化的时空分布，至今对该地区植被变化对区域气候水分的影响和反馈机理仍缺乏深刻的认识。本研究拟以高分辨率土地利用/覆盖变化和退耕还林资料为基础，分析黄河上中游近20年的植被覆盖变化特征；其次，利用先进的区域耦合模式WRF-Hydro，改进陆面水文参数化方案，针对黄河上中游地区植被变化进行高分辨率的耦合模拟，定量计算黄河源区草地退化及上中游地区退耕还林对流域水分平衡的各自贡献与综合效应，在流域尺度上探讨植被覆盖变化对区域降水的反馈及机理，评估植被变化特别是退耕还林对黄河上中游水资源的影响，为气候变化和人类活动背景下流域水资源管理和可持续发展提供科学依据。

Flowing across the semi-arid and semi-humid areas in China, the Yellow River Basin is important for runoff generation, sediment transportation and water consumption, all of which are vulnerable to land use/cover change (LUCC). In recent years, grassland degradation in the source region and afforestation in the Upper and Middle Yellow River Basin (UM-YRB) have become the most obvious characteristics of vegetation cover change, which leads to runoff reduction and soil desiccation. Due to the lack of accurate information on vegetation cover change in the UM-YRB, there is a limited understanding of underlying mechanisms that control the influences of vegetation cover change on the regional hydrological cycle and climate. In this study, we will analyze the characteristics of vegetation cover change in the UM-YRB during the last 20 years based on high-resolution LUCC products. Secondly, the advanced model WRF-Hydro with optimized hydrological parameterizations will be employed to conduct long-term simulations in the UM-YRB in order to compare the respective contributions of grassland degradation and afforestation and quantify the vegetation–precipitation feedbacks. Furthermore, these investigations allow for evaluation of the consequences of afforestation in the UM-YRB for water resources and provide a scientific basis for water resource management under climate change and LUCC.