基于改进 abcd 模型的黄河源区径流变化与归因

为改进模型对高寒地区融雪径流模拟不足的缺陷,将融雪模块耦合到传统 abcd 模型。利用 1980—2018 年逐月实测的径流数据和通过 AnuSpline 方法插值的格网气象要素,驱动改进后的abcd 模型,分析三江源生态保护措施实施前后（1980—1999 年和 2000—2018 年）黄河源区径流的动态变化,并量化关键气象因素与人类活动对径流变化的影响程度,即相对贡献。结果表明：耦合融雪模块的 abcd-snow 模型完善了高寒地区水文过程的模拟,提高对径流的模拟性能,在黄河源区表现出较好的适用性;整个研究时段黄河源区的实测径流呈不显著减少趋势（?0.80?mm/a,p>0.05）,但 2000 年前径流则呈现显著下降趋势（?4.12?mm/a,p<0.05）,2000 年后径流则呈显著增加趋势（3.16?mm/a,p<0.05）;?归因分析表明气候变化是源区径流变化的主导因素。2000 年前,气候变化对径流减少的相对贡献率为 62.8%,人类活动对径流的贡献为 37.2%;2000 年后,气候变化对径流增加的贡献率达到 120.0?%,人类活动对径流的贡献为?20.0%。其中：降水的变化是决定径流变化主导因素;其他气候因素的相对贡献较小;以人类活动为主的生态恢复可显著降低河川径流。本研究有助于理解气候变化和下垫面变化对黄河源区水资源变化的系统驱动机理,并为流域水资源合理配置提供科学参考依据。

Attribution analysis of runoff change based on the abcdmodel coupled with the snowmelt module in the source region of the Yellow River

Three Rivers Source is known as the "Chinese Water Tower" because it is an important water source conservation area in China and even in Asia. The change of runoff in the source region of the Yellow River in the Three Rivers Source played a crucial role in the ecological civilization and high-quality development of the Yellow River basin. Thus, it is of great scientific and practical significance to clarify the change of the runoff and its driving factor in the source region.The abcd -snow model coupled with the traditional abcd hydrological model and snowfall-snowmelt module was constructed to improve the traditional abcdmodel''s insufficient simulation of snowmelt runoff in alpine regions. Monthly observed runoff data and the measured meteorological data interpolated by AnuSpline software using more than 2000 meteorological stations from 1980 to 2018. The genetic algorithm was used to calibrate the abcd-snow model parameters. Among them, the data from 1980 to 1999 was used for model calibration, and from 2000 to 2018 was used for model validation. The Nash-Sutcliffe Efficiency, Kling-Gupta Efficiency, root mean square error and BIAS were used as indicators to evaluate the applicability of the abcd-snow model. With the aid of the abcd-snow model, the change dynamics of the runoff in the source region of the Yellow River before and after the ecological protection of the Three Rivers Source was analyzed. The contributions of climate change and human activities to runoff variability were analyzed and quantified based on the detrending method. Results showed that the abcd-snow model improved runoff simulation performance, and had good applicability in the source region of the Yellow River. The Nash-Sutcliffe Efficiency and Kling-Gupta Efficiency of the abcd-snow model were above 0.82. Compared with the traditional abcdmodel, the accuracy of the abcd-snow model is slightly improved, and the impact of different factors on the runoff change can be more reasonably analyzed. The observed runoff showed an insignificant decrease trend (slope=?0.80, p>0.05), but the runoff from 1980 to 1999 showed a significant decrease (slope=?4.12, p<0.05), and the runoff from 2000 to 2018 showed a significant increase trend (slope=3.16, p<0.05). From 1980 to 1999, the impact of climate change indicate a reduced runoff at a rate of 14.1 mm/a, with a relative contribution rate of 62.8 %. And from 2000 to 2018, climate change caused runoff to increase at a rate of 29.4 mm/a, with a relative contribution rate of 120 %. The contribution of precipitation to runoff change was the largest, with a relative contribution rate of 68.8% from 1980 to 1999 and 124.9% from 2000 to 2018. The contribution of other climatic factors to runoff change was limited, and the absolute value of the relative contribution was within 10%. Human activities reduced the runoff by 8.4 mm from 1980 to 1999, with a relative contribution rate of 37.2%. It decreased by 4.9 mm from 2000 to 2018, with a relative contribution rate of 20%. Climate change was the dominant factor in the change of runoff in the source region of the Yellow River. Among them, precipitation was the main driving factor determining the streamflow variation, and human activities dominated by ecological restoration could significantly reduce river runoff. This study could help to understand the mechanism of the impact of climate change on the runoff change in the Yellow River basin and provide a scientific reference for water resources planning in the basin.