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赣江上游桃江流域水沙变化及驱动因素

Changes and driving factors of runoff and sediment of Tao River watershed in the upper reach of Gan River

  • 摘要: 为揭示近年来赣江上游输沙量急剧减少的影响因素及其贡献率,以赣江上游桃江流域为例,采用流域内13个雨量站1958—2018年降水数据计算得出面雨量和流域控制站居龙滩站同期径流、输沙数据,结合趋势分析、突变检验等方法,对桃江流域61 a水沙变化特征进行分析,并采用累积量斜率变化率比较法计算气候因子和人类活动在各个时段对流域水沙变化的相对贡献率。结果表明:桃江流域多年平均降水量、径流量和输沙量分别为1 565.5 mm、60.36亿m3和112.5万t;流域61 a降雨和径流无显著变化趋势和突变点,但降雨、径流在1972和1985年有明显波动;年输沙量存在显著减少趋势(α < 0.01),在2002年发生突变(P < 0.001);若以人类活动相对较弱的1958—1972年为基准期,计算得到1973—1985、1986—2002和2003—2018年人类活动对流域输沙量减少的贡献率分别为79.14%、92.05%和100%;以水库建设为代表的水利工程和水土保持措施等人类活动是赣江上游桃江流域输沙量减少的主导因素。研究对于评价水利工程等人类活动对流域水沙的影响具有参考价值,可为流域实施水土保持措施提供科学依据。

     

    Abstract:
    Background The river system is an important and very active natural system on the earth, and the change of water and sediment is the direct response of the river system to climate change and human activities. The sediment load dramatically decreased at Tao River watershed, the upper Ganjiang River of China, due to natural and human factors. The objective of this study is to quantify the spatial and temporal variation of runoff and sediment load in the typical watershed in upper reaches of Ganjiang River and their potential causes. Better understanding the dynamic of hydrological processes may provide good reference for soil and water conservation, water resources planning and Ganjiang River basin management.
    Methods the Mann-Kendall test and Pettitt test were employed to investigate the temporal trends and abrupt changes of the annual runoff and sediment load at Julongtan gauging station of Tao River watershed from 1958 to 2018. Then the accumulation slope change rates were applied to analyze the relationship of rainfall-sediment during different periods and quantify the drivers of variation of runoff and sediment load.
    Results 1) The average annual precipitation, runoff and sediment transport in Tao River watershed were 1 565.5 mm, 6.036 billion m3 and 1.125 million t respectively. 2) The annual distribution of runoff and sediment was basically stable, mainly concentrated in April-June. 3) There was no significant change trend and abrupt change point in rainfall and runoff in the watershedof 61a, but rainfall and runoff fluctuated significantly in 1972 and 1985. The annual sediment discharge had no significant change trend before the 1990s, but has decreased significantly since the 1990s(α < 0.01), and an abrupt change occurred in 2002(P < 0.001). 4) According to the relative change point, the whole period was divided into four connected parts of 1958-1972 (stage A), 1973-1985 (stage B), 1986-2002 (stage C), 2003-2018 (stage D).When the period of 1958-1972 (stage A) with weak human activities was taken as a fundamental baseline, the contribution rate of the human intervention to sediment load in stage B, C and D was 79.14%, 92.05% and 100%. As time went on, human activities causeda greater and greater impact on sediment transport in Tao River watershed. 5) The construction of large-scale water conservancy facilities such as reservoirs and large-scale soil and water conservation measures are the driving factors for the reduction of sediment transport in Tao River watershed.
    Conclusions Integrating all these results, this work confirmed clearly that human activities are the main driving factor of variation of runoff and sediment load in the upper reaches of the Ganjiang River basin. The study has important practical significance for accurately evaluating the role of human activities such as hydraulic projects and the sustainable development of watersheds.

     

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