长江中游荆南三口断流时间演变特征及其影响机制

研究河道断流演变特征对认识区域水文过程及人类活动具有重要作用。论文依据1951—2014年水文气候实测数据,运用Mann-Kendall检验法,以及蒸散发-断流天数和降水-径流双累积曲线统计模型等方法分析了长江中游荆南三口断流时间演变特征及其影响机制,结果表明：1）对各时期荆南三口平均断流天数而言,1951—2014年呈逐期増加趋势,且趋势性变化显著,而在2003—2014年间,断流天数虽也增加,但趋势性变化不显著,即增加趋势逐渐减缓;2）影响荆南三口断流天数增减変化的是径流变化过程,而导致径流变化的又是以降水和蒸散发为代表的气候因素和以水利工程、各行业（农业）用水为标志的人类活动;3）影响荆南三口断流天数持续增加的主要驱动因素是人类活动,以各自时段前一时段为基准期,1959—1966、1967—1972、1973—1980、1981—2002、2003—2014年的5个变异期中,气候波动对荆南三口断流天数增加的贡献率依次为24.93%、19.05%、6.36%、10.38%、7.56%;人类活动影响的贡献率分别为75.07%、80.95%、93.64%、89.62%、92.44%。

Temporal Evolution of Dried up Days and the Influencing Mechanisms at Three Outlets along Jingjiang in the Middle Reach of Yangtze River

The evolution characteristics of dried up days of river play an important role in recognizing the regional hydrological processes and clarifying the influencing mechanism of human activities, such as hydraulic engineering and water allocation in various fields. Based on the hydrological and climatic data from 1951 to 2014, this study uses Mann-Kendall methods and statistic models of precipitation and runoff accumulation curve to analyze the temporal evolution of dried up days and the influencing mechanisms at the Three Outlets of southern Jingjiang in the middle reach of Yangtze River. The results are as follows: 1) The average dried up days at the Three Outlets increased during 1951-2014 and the trend was significant. The average dried up days also increased during the period of 2003-2014, but the trend was not obvious, namely, the increase trend of the dried up days slowed down. 2) The variation of dried up days was controlled by the variation of runoff at the Three Outlets. And the runoff variations could be explained by climate fluctuations, such as precipitation and evapotranspiration, and human activities, such as hydraulic engineering and water allocation. Which one is the main control remains uncertain. So it is important to separate the influence factors. 3) Using the previous period as the reference period, the contributions of climate fluctuation to the increment of dried up days in each period were 24.93%, 19.05%, 6.36%, 10.38% and 7.56% during the five periods (1959-1966, 1967-1972, 1972-1980, 1981-2002 and 2003-2014), respectively, whereas the contributions of human activity were 75.07%, 80.75%, 93.64%, 89.62% and 92.44% respectively. The result revealed that the increment of dried up days was mainly dominated by human activities from 1951 to 2014.