东北寒区降水组分变化及其对流域径流的影响

As one of the most important components in the water cycle, precipitation can be separated into rain and snow because of different phases. Precipitation in different phases always play distinct role in the runoff, energy flux, and material balance. With the global climate change, the temperature-induced shift of precipitation from snow towards rain and earlier melt of the snowpack in the cold regions has become one of the most profound and widely anticipated changes in the hydrological cycle. However, the influence of the change in the form of precipitation on the long-term mean streamflow is generally not included in the current studies. Therefore, this project intends to select the Songhua River Basin, which is a typical cold region, as the study area, and 1) to establish a terrain and climate based method to separate rain and snow, and investigate the spatio-temporal variabilities of precipitation components; 2) to clarify the mechanism of the impact of snow on a basin’s water-energy balance, based on the observation of snow sublimation and the Budyko framework, and develop a water-energy balance model considering the effect of snow to quantitatively evaluate the effects of changes in precipitation components on the long-term runoff; 3) and finally to predict the changes of precipitation components and the runoff response in the near future with different climate change scenarios combined with the statistical downscaling method. This project will provide a new insight on the study of climate change impacts on water resources, enrich the theory and contents of cold region water resources study under the changing climate, and can serve as a theoretical basis for regional water resources management and reasonable regulation in the Songhua River Basin.

降水是水循环最重要的组分之一，按其形态主要分为降雨和降雪，不同形态的降水对径流、能量流动和物质循环具有截然不同的作用。全球气候变化背景下，温度升高引起高纬度寒区降水形态由降雪向降雨的转变以及融雪时间的提前已成为当前最为突出且可能造成广泛影响的水循环问题之一。然而，目前关于降水组分变化及其对流域径流影响方面的研究较少。因此，本课题拟选取典型寒区松花江流域为研究对象，建立基于地形和气象要素的降水形态判别方法，明确流域降水组分时空演变规律；基于Budyko假设和野外观测，弄清降雪对水热平衡的影响机理，构建考虑降雪的流域水热平衡模型，定量分析降水组分变化对径流的影响；结合未来气候变化情景和统计降尺度方法，预测流域未来降水组分变化及径流响应特征。本项目将为气候变化对流域水资源影响研究提供新的理论和思路，丰富气候变化背景下寒区水文水资源研究的理论和内容，为松花江流域水资源科学管理和合理配置提供依据。

作为水循环最重要的组分之一，降水按其形态主要分为降雨和降雪，不同形态的降水对径流、能量流动和物质循环具有截然不同的作用。全球气候变化背景下，温度升高引起高纬度寒区降水形态由降雪向降雨的转变以及融雪时间的提前已成为当前最为突出且可能造成广泛影响的水循环问题之一。然而，目前关于降水组分变化及其对流域径流影响方面的研究较少。 本课题选取典型寒区松花江流域为研究对象，确定了研究区降水形态判别方法，阐明了流域降水组分时空演变规律；基于Budyko假设和前人研究经验，明确了降雪对水热平衡的影响机理，定量分析了降水组分变化对径流变化的贡献程度；结合未来气候变化情景和统计降尺度方法，初步预测了流域未来降水组分和径流的变化。本项目研究成果可以丰富气候变化背景下寒区水文水资源研究的理论和内容，为松花江流域水资源科学管理和合理配置提供依据。