为弥补传统整数阶导数对流-弥散方程在潜流带溶质运移模拟时难以描述介质非均质性引起的溶质运移的不足，在潜流带溶质运移模型中引入时空分数阶导数项，分别从一维和二维角度出发对分数阶导数方法在潜流带溶质运移模拟中的适用性进行讨论。研究发现：时间分数阶阶数α体现溶质运移过程的滞时效应，使穿透曲线具有明显的拖尾特征；空间分数阶阶数β刻画介质非均质性引起的溶质超扩散现象。参数敏感性分析结果表明：引入分数阶方法相较于传统对流-弥散方程使得方程对流速和弥散系数改变的敏感性增强，解决了传统整数阶方法无法准确描述潜流带中介质强非均质性的缺陷。野外示踪试验进一步证明：由于潜流带中介质非均质性强且存在多维流的特点，传统二维整数阶对流扩散方程对溶质运移过程刻画存在不足；一维分数阶导数模型在模拟潜流带溶质运移时，能够更准确计算溶质浓度峰现时间，描述穿透曲线拖尾现象；二维分数阶导数模型受到不同方向参数设置的影响，在没有纵深方向介质差异导致的水流、介质参数差异的前提下，模拟水平面内溶质扩散过程更具适用性。

hyporheic zone is a saturated sediment layer with the interaction between surface and groundwater in rivers.The riverbed medium is highly inhomogeneous and the flow direction is complex.Solute diffusion is prone to exhibit abnormal diffusion characteristics of trailing and non-Gaussian distribution.It is difficult to describe such diffusion characteristics by traditional convection dispersion equation.Therefore,a space-time fractional derivative term is introduced in the hyporheic zone solute transport model,and the applicability of the fractional derivative method in the hyporheic zone solute transport simulation is discussed from one-dimensional and two-dimensional perspectives,respectively. The influence of fractional order on the physical meaning of solute transport and the sensitivity of fractional order to physical parameters of solute transport were discussed.A two-dimensional fractional-order derivative model was also established to compare the simulation results of different dimensions to the fractional-order derivative method with field tracing experiments. The physical significance of fractional order is analyzed and it is found that timefractional orderαreflects the lagging effect of the solute transport process and makes the breakthrough curve have obvious trailing characteristics.Space fractional-order β characterize the phenomenon of solute hyper-diffusion caused by inhomogeneity of media.The results of parameter sensitivity -analysis show that the fractional-order method is more sensitive to velocity and dispersion coefficient than the traditional convection-dispersion equation.It overcomes the defect that the traditional integer-order method can not accurately describe the strong inhomogeneity in the hyporheic zone.Field tracing test shows that the traditional two-dimensional integer-order convection-diffusion equation has shortcomings in characterizing the solute transport process due to strong inhomogeneity and multi-dimensional flow in the hyporheic zone.The one-dimensional fractional derivative model can more accurately calculate the peak time of solute concentration and describe the tailing phenomenon of the penetration curve when simulating the solute transport in the hyporheic zone.Affected by parameter settings in different directions,the simulation results of the two-dimensional fractional-order model are inferior to the one-dimensional fractional-order model.However,more point-level solute data can be observed on the isometric plane by the two-dimensional fractional-order model and it would be more applicable without the difference of flow and medium parameters caused by medium differences in the depth direction. Although the applicability of one-dimensional and two-dimensional fractional derivative models differs in different scenarios,the introduction of fractional derivative improves the simulation effect of traditional convection-dispersion equations and is suitable for special media with strong inhomogeneity and complex flow conditions,such as hyporheic zone.