2011-2020年赣江上游主要支流水沙变化特征

Variation of Runoff and Sediment in the Main Tributaries of the Upper Ganjiang River in the Period from 2011 to 2020

[目的]探讨近十年来赣江流域上游主要支流水沙变化的基本特征,阐明赣江上游水土保持措施与河川输沙量的关系,为赣江流域的水土流失综合治理提供科学依据。[方法]以赣江流域上游4条主要支流把口站2011—2020年水沙实测资料为基础,采用累积距平、双累积曲线等方法对支流水沙变化特征进行分析,并结合相关水土保持措施统计数据对输沙模数进行线性回归分析。[结果](1)赣江上游主要支流的降雨量和径流量的变化趋势大体相同,主要支流的输沙量呈现“丰水丰沙,贫水贫沙”的特征。(2)四条支流的输沙量均表现出持续2~3 a的上升(下降)随后出现下降(上升)的间歇性态势。除平江流域外其他流域输沙能力受非自然因素影响较大,影响因素较为复杂。(3) 2011—2020年赣江流域上游支流中平江、桃江及贡水流域输沙模数与5个水土保持因子无显著相关关系。章水流域输沙模数与新增水保林面积呈显著正相关。章水流域输沙模数与水土保持措施因子的关系方程如下:Mz=0.019S水保林+5.126(Mz表示章水的年输沙模数,S水保林代表对应支流流域内水土保持措施年新增面积)。(4)提出新增水土保持措施的面积占比:封育治理(52.0%~60.0%),经果林(22%~25%),水保林(20%~23%),种草(2%~3%),坡改梯(2%~3%)。[结论]赣江上游主要支流的降雨量和径流量的变化特征大体相同,但个别年份存在径流量与降雨量不成正比的反常情况。影响赣江上游主要支流输沙能力的因素较为复杂,其中水土保持措施是影响赣江上游章水流域水沙变化的主要人为因素,章水流域输沙模数与新增水保林面积呈显著正相关。

[Objective]The aims of this study are to explore the variation characteristics of runoff and sediment in the main tributaries of Ganjiang River watershed,to quantify the relationship between water and soil conservation measures and sediment transport in the upper reaches of Ganjiang River,and to provide a theoretical basis for soil erosion comprehensive management in Ganjiang River watershed.[Methods]Based on the measured runoff and sediment data of four main tributaries in Ganjiang River watershed from^(2)011 to 2020,hydrological analysis,cumulative anomaly and double cumulative curve method were used to study runoff and sediment variation.Meanwhile,linear regression analysis was carried out to quantify the relationship between soil and water conservation measures and sediment transport based on the statistical data of soil and water conservation measures in Ganzhou.[Results](1)Variation trend of rainfall and runoff in the main tributaries of the upper reaches of Ganjiang river was roughly the same.The sediment transport of the main tributaries of the upper Ganjiang River changed with the variation of runoff,presenting a situation of abundant water and abundant sediment,poor water and poor sediment.(2)Sediment discharge in the four basins showed an intermittent trend of increasing(decreasing)and then decreasing(increasing)at two-year or three-year intervals.(3)Linear regression analysis quantified the response of sediment transport modulus to the scale of soil and water conservation measures:M z=0.019 S water conservation forest+5.126(M z representing the annual sediment transport module of Zhangshui,S water conservation forest representing the annual increase area of soil and water conservation measures in the corresponding tributary watershed).(4)Based on the structure of soil and water conservation measures in Ganzhou,the optimal area proportion of newly incremental water and soil conservation measures was put forward:enclosure management(52.0%~60.0%),fruit forest(22%~25%),water conservation forest(20%~23%),grass planting(2%~3%),slope improvement(2%~3%).[Conclusion]Variation trend of rainfall and runoff in the main tributaries of the upper reaches of Ganjiang river was roughly the same between the year of 2011 and the year of 2020,except the year of 2018.The factors affecting sediment transport of the main tributaries of the upper Ganjiang River are complex.Soil and water conservation measures were the dominant human activities for variation of runoff and sediment load in Zhangshui River Watershed.There was a significant positive correlation between sediment transport modulus and newly increased forest area in Zhangshui River Watershed.