海河流域山区过去六十年在气候变化与以大规模植被恢复为主的人类活动的综合影响下，水循环系统及生态系统的平衡发生显著变化。流域山区作为京津冀的水源涵养区和我国三北防护林工程的重要组成部分，不仅是拱卫京津冀和海河流域生态安全的重要屏障，同时也对平原区社会经济发展起到关键支撑作用。然而，在变化环境下有关海河流域山区水循环演变特征、“水-碳”权衡关系、植被对干旱响应规律等方面的认识尚不清晰，有待进一步研究。本论文基于历史水文气象观测数据，应用分布式水文模型GBHM等方法分析了气候变化和人类活动影响下海河流域山区水文循环演变特征，阐明了产流能力下降的重要影响因素；分析了植被恢复对流域山区生态水文过程影响，从“水-碳”权衡关系的角度评估了植被恢复的影响；分析了变化环境下流域山区干旱时空演变及其对植被的影响，综合评估了流域变化环境下水分对植被生长限制的变化特征，系统探究了不同子流域植被胁迫事件的受损、恢复时间的特征及影响因素。论文的主要结果如下：过去六十年间，海河流域山区降雨模式逐渐趋于平稳，平均气温显著增加，多年平均径流深显著的下降，产流特征发生明显改变。其中，人类活动对径流减少的贡献在50.3%~80.6%之间，是导致流域年径流显著下降的最主要因素。而植被恢复与年径流减少存在负相关关系，且越干旱的地区，年径流对于植被变化越敏感。在植被恢复为主的人类活动影响下，海河流域山区的植被覆盖度显著增加，年径流深显著下降。尤其在近10年间，人类活动引起的LAI增加量也已经占到实际LAI的20%以上,而R的减少量则占到实际R的20%。植被恢复使得流域山区的“水-碳”关系存在互相权衡。在气候变化与人类活动的综合影响下海河流域山区干旱频率、强度和影响面积不断增加。植被对干旱响应规律变化显著，最近20年内的植被抵抗力仅占到天然情景的80%左右。其中，植被受损主要受到植被恢复量、平均土壤含水率、干旱平均强度、平均气温等因素的影响，而植被恢复时间主要受到平均气温、植被最大受损、VPD、最低土壤含水率等因素的影响。
In the past sixty years, under the combined influence of climate change and human activities, mainly large-scale vegetation restoration, the balance of the water cycle system and ecosystem in the mountainous areas of the Haihe River Basin has changed significantly. As the water conservation area in the Beijing-Tianjin-Hebei region and an important part of my country‘s Three-North Shelterbelt Project, the mountainous areas in the basin are not only an important barrier to protect the ecological security of the Beijing-Tianjin-Hebei and Haihe River basins, but also play a key supporting role in the socio-economic development of the plain areas. However, under a changing environment, the understanding of the evolution characteristics of the water cycle, the "water-carbon" trade-off relationship, and the response of vegetation to drought in the mountainous areas of the Haihe River Basin is still unclear and needs further research.Based on historical hydrometeorological observation data, this paper uses distributed hydrological model GBHM and other methods to analyze the evolution characteristics of the hydrological cycle in the mountainous areas of the Haihe River Basin under the influence of climate change and human activities, and clarifies the important influencing factors of the decline in runoff production capacity; analyzes the impact of vegetation restoration on The influence of ecological and hydrological processes in mountainous areas of the watershed was evaluated from the perspective of the "water-carbon" trade-off relationship; the spatiotemporal evolution of drought in mountainous areas of the watershed and its impact on vegetation was analyzed under a changing environment, and the impact of water on vegetation was comprehensively assessed under a changing environment. The changing characteristics of vegetation growth limitation were systematically explored in different sub-watersheds, the characteristics of damage and recovery time and influencing factors of vegetation stress events. The main results of the paper are as follows:Over the past sixty years, the rainfall pattern in the mountainous areas of the Haihe River Basin has gradually stabilized, the average temperature has increased significantly, the average multi-year runoff depth has significantly decreased, and the runoff generation characteristics have changed significantly. Among them, the contribution of human activities to runoff reduction ranges from 50.3% to 80.6%, which is the most important factor leading to the significant decline in annual runoff in the basin. There is a negative correlation between vegetation recovery and annual runoff reduction, and in drier areas, annual runoff is more sensitive to vegetation changes.Under the influence of human activities dominated by vegetation restoration, the vegetation coverage in the mountainous areas of the Haihe River Basin has increased significantly, and the annual runoff depth has decreased significantly. Especially in the past 10 years, the increase in LAI caused by human activities has accounted for more than 20% of the actual LAI, while the decrease in R has accounted for 20% of the actual R. Vegetation restoration creates a trade-off in the "water-carbon" relationship in mountainous areas of the watershed.Under the combined influence of climate change and human activities, the frequency, intensity, and affected area of droughts in the mountainous areas of the Hai River Basin continue to increase. The response pattern of vegetation to drought changes significantly, and the vegetation resistance in the past 20 years only accounts for about 80% of the natural scenario. Among them, vegetation damage is mainly affected by factors such as vegetation recovery amount, average soil moisture content, average drought intensity, average temperature, etc., while vegetation recovery time is mainly affected by factors such as average temperature, maximum damage to vegetation, VPD, minimum soil moisture content, etc. Influence.
