This study is concerned with the flow characteristics in compound channels aiming to predict an accurate method for estimating the discharge passing through compound sections. Also it is aiming to study the flow characteristics of compound sections and trying to develop formula defining the flow behavior and its dynamics at compound sections. The study is performed experimentally in a rectangular compound section having a single floodplain. The height of main channel is changed twice to take 9cm and 15 cm. The channel bed slope is changed between 0.00243 up to 0.0037. The roughness of the channel bed is changed twice. The discharge is changed to give a range of Froude number between 0. 12 and 0.73. The ratio of floodplain depth to the main channel one (df/dm) is changed to take values between 0.22 and 0.78. Vertical photos are taken to define the lateral velocity directions. The velocity is measured by a calibrated current meter. The actual discharges are measured by means of a calibrated nozzle – meter. The results revealed that the interaction between floodplain and main channel is minimum at a horizontal plain having a level equal to 0.4 floodplain depth (0.4df). The best subdivision used for discharge estimation with minimum error is found at this level. It is found that, the capacity of compound section increases in a linear relationship with the ratio of floodplain depth to that of main channel.