Marsh vegetation, a definitive component of delta ecosystems, has a strong effect on sediment retention and land-building, controlling both how much sediment can be delivered to and how much is retained by the marsh. An understanding of how vegetation influences these processes would improve the restoration and management of marshes. We use a random displacement model to simulate sediment transport, deposition, and resuspension within a marsh. As vegetation density increases, velocity declines, which reduces sediment supply to the marsh, but also reduces resuspension, which enhances sediment retention within the marsh. The competing trends of supply and retention produce a nonlinear relationship between sedimentation and vegetation density, such that an intermediate density yields the maximum sedimentation. Two patterns of sedimentation spatial distribution emerge in the simulation, and the exponential distribution only occurs when resuspension is absent. With resuspension, sediment is delivered farther into the marsh and in a uniform distribution. The model was validated with field observations of sedimentation response to seasonal variation in vegetation density observed in a marsh within the Mississippi River Delta.

沼泽植被是三角洲生态系统的决定性组成部分，对沉积物保留和土地建设有很大影响，控制着多少沉积物可以输送到沼泽地，多少沉积物被沼泽保留。了解植被如何影响这些过程将改善沼泽的恢复和管理。我们使用随机位移模型来模拟沼泽内的沉积物运输、沉积和再悬浮。随着植被密度的增加，速度下降，这会减少对沼泽的沉积物供应，但也会减少再悬浮，从而增强沼泽内的沉积物保留。供应和保留的竞争趋势在沉降和植被密度之间产生非线性关系，因此中等密度产生最大沉降。模拟中出现了两种沉积空间分布模式，指数分布仅在没有再悬浮时出现。通过再悬浮，沉积物被输送到更远的沼泽中并均匀分布。该模型通过在密西西比河三角洲内的沼泽中观察到的对植被密度季节性变化的沉积响应的现场观察进行了验证。