Velocity and forces on individual plants were measured within an emergent canopy with real plant morphology and used to develop predictions for the vertical profiles of velocity and turbulent kinetic energy (TKE). Two common plant species, Typha latifolia and Rotala indica, with distinctive morphology, were considered. Typha has leaves bundled at the base, and Rotala has leaves distributed over the length of the central stem. Compared to conditions with a bare bed and the same velocity, the TKE within both canopies was enhanced. For the Typha canopy, for which the frontal area increased with distance from the bed, the velocity, integral length‐scale, and TKE all decreased with distance from the bed. For the Rotala, which had a vertically uniform distribution of biomass, the velocity, integral length‐scale, and TKE were also vertically uniform. A turbulence model previously developed for random arrays of rigid cylinders was modified to predict both the vertical distribution and the channel‐average of TKE by defining the relationship between the integral length‐scale and plant morphology. The velocity profile can also be predicted from the plant morphology. Combining with the new turbulence model, the TKE profile was predicted from the channel‐average velocity and plant frontal area.

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.

The transport of sediment in regions with vegetation plays an important role in aquatic ecosystems and landform evolution in river deltas. In this study, flow parameters and suspended sediment concentration (SSC) within an emergent canopy with real plant morphology (Typha latifolia) were measured in a laboratory channel. T. latifolia is a common marsh species with multiple thin leaves emerging from a tight bundle (culm) at the bed. The observed equilibrium SSC profile differed significantly from a Rouse profile, the classic model for SSC over bare beds. The vertical distribution of SSC was nearly uniform in the culm region of the canopy, and decreased with height in the upper canopy region of distributed leaves. The profile of SSC reflected the vertically nonuniform turbulent diffusion, which arose from the plant morphology. A diffusivity model based on cylinder arrays was first validated with tracer data and then adapted to the T. latifolia morphology, providing a way to model turbulent diffusivity in marsh systems. The diffusivity model was successfully used within a random displacement model to predict the spatial evolution and equilibrium SSC profile within the T. latifolia canopy.

Branching networks are key elements in natural landscapes and have attracted sustained research interest across the geosciences and numerous intersecting fields. The prevailing consensus has long held that branching networks are optimized and exhibit fractal properties adhering to power-law scaling relationships. However, tidal networks in coastal wetlands and mudflats exhibit scaling properties that defy conventional power-law descriptions, presenting a longstanding enigma. Here we show that the observed atypical scaling represents a universal deviation from an ideal fractal branching network capable of fully occupying the available space. Using satellite imagery of tidal networks from diverse global locations, we identified an inherent “laziness” in this deviation—where the increased ease of channel formation paradoxically decreases the space-filling efficiency of the network. We developed a theoretical model that reproduces the ideal fractal branching network and the laziness phenomenon. The model suggests that branching networks can emerge under a localized competition principle without adhering to conventionally assumed optimization-driven processes. These results reveal the dual nature of branching networks, where “laziness” complements the well-known optimization process. This property provides more flexible strategies for controlling tidal network morphogenesis, with implications for coastal management, wetland restoration, and studies in fluvial and planetary systems.