In this study, physical experiments were performed to investigate the influence of two key morphological factors in paddy fields, i.e., paddy ridges and irrigation channels, on sediment deposition during fluvial inundation. The inlet boundary was given constant water and sediment discharges to simulate embankment failure conditions. Hydraulic parameters show that sediment came into the floodplain in the form of suspended load. By changing the outlet boundary and channel outlets conditions, three groups of experiments were conducted. The results show that, under the high-water-level scenario (with a wall at the outlet boundary), sediment mainly deposited along the main flow path, and the influence of paddy ridges was only constrained in its surroundings because of the three-dimensional flow characteristics. The operation of the channel outlets effectively changed the water depth and main flow direction and accordingly influenced the sedimentation distribution on the land surface. Under the shallow-water-depth scenario (open outlet boundary), the ridges on the bed retained more sediment by decreasing the bed-load transport rate. The intersection of the channel and main flow path was blocked by the bed load from the land surface. Hence, setting ridges close to the channel could remarkably relieve sedimentation. The experimental results are helpful for better understanding the mechanism of sediment deposition on paddy fields with complex topography and can provide data for numerical model verification.