<p>Despite of extensive studies on the flow patterns in both smooth and vegetated meandering compound channels, there is a lack of researchs regarding the effect of obstacles in the floodplains on the flow characteristics and the flood risk management. As it is important to determinate the stage-discharge relation and flood risk management, especially in flood-prone urban areas, aim of present research is to understand the flow characteristics in compound curved channels with different densities of obstacles in the floodplains. A numerical study was conducted using FLOW-3D to simulate three-dimensional flow in a compound curved channel with five different obstacle densities. (2.8%, 4%, 6.3%, 11%, and 25%, respectively). High-quality experimental data sets available in the literature were used to validate computed results. The results showed that there is a reasonable agreement between computed and measured results. As the density of obstacles increases, the slope of the stage-discharge relationship curve increases. Furthermore, a clockwise secondary current cell occurs near the bottom of the inner sidewall of the apex section. The locations of the maximum bed shear stresses move from the inner sidewall to the central area of the main channel. Modeled maximum turbulence intensities occur at the bank-full elevation. For river engineers, an in-depth understanding of the flow structure and momentum transport in compound meandering channels with different density of obstacles can significantly help in studying the transport and diffusion patterns of sediments and pollutants in rivers.</p>