塔里木河干流上中游河床沉积物粒度分形特征初探

The Granularity Fractal Characteristics of Riverbed Sediments in the Upper and Middle Reaches of Tarim River

利用体积分形维数模型对塔里木河干流上中游河床沉积物的粒度分形特征进行分析,并探讨了沉积物分形维数与粒度组成、粒度参数的相关关系,结果表明：（1）塔里木河干流上中游河床沉积物粒度粒径介于0～9 mm,黏粒、粉粒与砂粒含量的均值分别为11.46%、53.29%和35.25%,采集样品中有2/3为细粒土,其余为细粒土质砂,沉积物质地相对较细。（2）沉积物体积分形维数介于1.921～2.403,均值为2.114,河床沉积物粒度组成相对简单。（3）沉积物分形维数与黏粒及粉粒含量呈显著的正相关关系,相关系数分别为0.594、0.372,与砂粒含量呈显著的负相关关系,相关系数为-0.538,分形维数越大,沉积物质地越细。（4）分形维数与平均粒径呈显著的负相关关系,相关系数为-0.529,与标准差、偏度和峰度呈现显著的负相关关系,相关系数分别为0.272、0.714和0.483,分形维数可反应沉积物粒度参数的综合特征。

In this paper, the fractal characteristics of riverbed sediments in the upper stream of Tarim River were analyzed with the volume fractal model, and the relationship between fractal dimension and grain size composition and parameters of the sediment was also discussed. The results showed as follows：（1） The grain of sediment was relatively fine. Particle size of sediment was from 0 to 9 mm. The mean content of clay, silt and sand were, respectively, 11.46%,53.29% and 35.25%. About 2/3 of samples was fine grained soil, and the rest were fine grained soil sand.（2） The fractal dimension of sediment ranged from 1.92 to 2.40 and the mean was 2.12, which meant the composition of river bed sediment was relatively simple.（3） The correlation between sediment fractal dimension and the content of clay and silt was significantly positive with correlation coefficients of 0.594 and 0.372, respectively. Meanwhile, correlation coefficient between the sediment fractal dimension and the content of sand was-0.538, which meant a negative correlation. The greater the fractal dimension, the finer the grain of sediment.（4） The fractal dimension had a negative correlation with the average particle size, and the correlation coefficient was-0.529. The fractal dimension and the standard deviation, skewness and kurtosis had negative correlation with correlation coefficient of 0.272, 0.714 and0.483, respectively. Fractal dimension reflected the comprehensive features of sediment grain size parameters. The study can provide certain scientific basis for the application of fractal dimension and the research of sediment source and deposition process, etc. in the Tarim River.