Understanding scalar transport in solvents is important in chemical engineering, pollution control, and water remediation, where the longitudinal dispersion coefficient (LDC) is a key parameter for describing solute transport in fluids. For flow in classic conditions such as in a pipe or a regular open channel, formulas for LDC are derived from adopting the ideas of the advection–diffusion equation. However, when the flow encounters large-scale roughness, such as an open channel with vegetation, longitudinal dispersion becomes complicated. This paper aims to estimate LDC in an open channel that is partially covered with artificial vegetation. This kind of artificial vegetation is emergent, which comprises eight floats. A two-zone model is proposed to determine LDC in this channel condition. In validating our model, experiments are conducted with Rhodamine as a tracer, whose time-concentration curves are …