气候变化和人类活动对黄河流域“三水”转化过程的影响研究

The Yellow River is a critical water resource for Northwest and North China. Due to climate change, land use/cover change (LUCC), and increased human consumption of water, significant changes in the water cycle have taken place within the Yellow River basin (YRB) during the recent years. However, the processes that lead to these changes are still not well understood because of the lack of studies in the coupling mechanisms of the “Three-Waters” (atmospheric water, land surface water, and underground water) at basin scale. By utilizing climatic and hydrologic observations, remote sensing products, and Global Land Data Assimilation System (GLDAS) datasets along with numerical simulation techniques, this study intends: first, to investigate the historical variations of precipitation, evapotranspiration, runoff, soil moisture, and underground water, and the quantitative relationships of transformations among the “Three-Waters” in YRB under scenarios of climate change and human activities; second, to establish a regional coupled climate-vegetation-hydrology (surface and underground water) model to simulate and study the “Three-Water” transformation mechanisms; and finally, to investigate the relative contributions to Three-Water transformation processes and regional water cycle from climate change, LUCC, and human consumption of water, respectively. Based on a comprehensive analysis of their integrated influence, estimation for the projected changes in YRB water resources for the next 10-30 years will be generated. This study will provide the theoretical basis for YRB water-resource security and response to climate change, and in the meantime, serve the regional sustainability and ecological civilization.

黄河是我国西北、华北的重要水源。近年来，受气候变化、土地利用/覆盖变化（LUCC）和人类用水增加的影响，黄河流域水循环发生了显著的变化，但由于缺乏在流域尺度上大气水、地表水和地下水“三水”耦合机制的研究，引起这些变化的机理还不甚清楚。基于此，该项目拟利用气候、水文、遥感观测和全球陆面同化数据（GLDAS）并结合数值模拟手段，首先从降水、蒸发散、径流、土壤湿度和地下水的变化出发，分析在气候变化和人类活动共同作用下，黄河流域的“三水”变化特征和它们之间的定量转换关系；其次，建立区域气候-植被-水文（地表水和地下水）的耦合模式，研究流域尺度“三水”耦合和转换机制；最后，分析气候变化、LUCC和人为用水对“三水”转换过程和区域水循环变化的相对贡献及综合效应，预估未来10-30年黄河流域水资源变化。该项研究的开展将为黄河流域水资源安全和应对气候变化提供理论依据，服务于区域的可持续发展和生态文明建设。

黄河是我国西北和华北地区的重要水源。近年来，受气候变化、土地利用/覆盖变化（LUCC）和人类用水增加的影响，黄河流域水循环发生了显著的变化，但由于缺乏在流域尺度上大气水、地表水和地下水“三水”耦合机制的研究，引起这些变化的机理还不甚清楚。为此，该项目利用气候、水文、遥感观测和全球陆面同化数据（GLDAS）并结合数值模拟手段，从降水、蒸发散、径流、土壤水、地下水以及陆地水储量的变化出发，揭示了黄河流域“三水”的变化特征及其转换的规律；阐明了气候变化和人为过程对黄河流域“三水”转换的影响，并定量区分了气候变化、LUCC和人为用水对流域水循环变化的相对贡献及综合效应；预估了未来全球升温1.5℃和2℃黄河流域水资源的可能变化。研究发现黄河流域年平均气温在1951–2018 年间升高1.39℃，而年降水量却减少10 mm，流域整体趋于暖干化，同时水资源开发利用率~61%已经远超国际公认的40%警戒线，水资源供需矛盾突出。黄河源区陆地水储量增加主要是由于径流和土壤含水量增加，兰州以下地区陆地水储量显著减少，其中径流、土壤水和地下水都在减少。流域植被变化和人类用水已经成为影响干旱的重要因素，黄河中游地区植被覆盖改善对天然径流减少的贡献率为~19%，并且农田灌溉耗水的增多加速了陆地水储量减少（贡献率4.9%）。在升温1.5℃时，黄河流域的北部很有可能会变得更干，升温2℃时整个黄河流域除了源区都很有可能会变干。该项研究的开展可以为黄河流域水资源安全和应对气候变化提供理论依据，为黄河流域生态保护和高质量发展提供科学支撑。