复合点坝侧积周期的成因分析:以密西西比河下游段为例*

复合点坝侧积体定量成因分析是河流沉积学研究的难点之一。通过选取密西西比河下游段激光雷达数据,剖析复合点坝侧积体的内部特征,统计侧积体高程数据,发现其符合周期变化的特点。对高程数据进行傅里叶变换计算,得到复合点坝侧积周期,将侧积周期与河道规模进行拟合,两者符合线性关系,拟合度高。深入分析后,认为侧积周期受河流的季节性洪泛周期控制。研究结论为侧积体定量成因分析提供了理论依据。

Analysis of formation of lateral accretionary period of composite point bar: taking the lower reaches of Mississippi River as an example

It is one of the challenges in fluvial sedimentology to analyze the quantitative genesis of the lateral accretionary body of composite point bar. By selecting lidar data from the lower reaches of the Mississippi River,the internal characteristics of the lateral accretion of the composite point bar and the elevation data of the lateral accretion are analyzed,showing the characteristics of periodic changes. The Fourier transform calculation of the elevation data is used to obtain the lateral accumulation period of the compound point bar,which is highly fitted to the scale of the river channel. It implies that the lateral accumulation cycle is controlled by the seasonal flooding cycle of the river. The results provide a theoretical basis for quantitative genesis analysis of lateral accretionary body.