A new formula for the concentration profile of nonuniform sediment is derived using the diffusion differential equation with equilibrium bed concentration. The interaction coefficient for nonuniform sediment particles as a function of both relative diameter and geometric standard deviation of nonuniform sediment is taken into account in the settling velocity. The diffusion coefficient is obtained from the logarithmic velocity profile. This new formula possesses several advantages as follows: (1) avoids theoretical defect of the Rouse formula, which states that the sediment concentration is infinite at the bottom and zero at the water surface. (2) suitable for an arbitrary fraction of nonuniform sediment, and (3) easy to apply with a simple form. The formula yields less difference among concentration profiles for various particles than that for uniform sediment and reveals the law for fractional concentration distribution of nonuniform sediment. The calculated concentration agrees well with the measured data from the Yangtze River.

利用具有平衡床浓度的扩散微分方程，导出了非均匀沉积物浓度分布的新公式。在沉降速度中考虑了非均匀沉积物颗粒的相互作用系数，该相互作用系数是相对直径和非均匀沉积物几何标准偏差的函数。扩散系数从对数速度曲线获得。该新公式具有以下优点：（1）避免了Rouse公式的理论缺陷，该公式指出沉积物浓度在底部为无限，在水面为零。（2）适用于任意分数的不均匀沉积物，（3）易于使用，且形式简单。该公式得出的各种颗粒物浓度分布之间的差异要比均匀沉积物的差异小，并揭示了不均匀沉积物的分数浓度分布规律。计算得出的浓度与长江测得的数据非常吻合。