Abstract:
The St. Venant's equations still represent the state-of-the-art for simulating the transient flow in open channels and hence forms the basis of our understanding on the channel flow behaviour. Ponce and Simons(1977) first derived the analytically the wave propagation characteristics in wide rectangular open channels using linear theory under the assumption that the Chezy's friction holds good, and the stage and discharge waves are of sinusoidal form. Based on their works Ponce et al.(1978) developed depth specific criteria for identifying wave kind occurring in the channel using the flow and channel characteristics.
Since the Manning's equation is preferred to Chezy's by practising engineers, the works of Ponce and Simons (1977) and Ponce et al.(1978) on shallow wave propagation in open channels using Chezy's friction are re-analysed in Manning's perspectives. Its use in the development of the applicability criteria for kinematic wave model decreased dimensionless time periods from 873, 171, 83 to 707, 139, 67 corresponding to 99, 95 and 90 percent accuracies, respectively. In case of diffusion wave model, the ratio of dimensionless time period to Froude number comes out to be 22 as against 30. The applicability horizon of these models is widened and the efficiency of the Muskingum Cunge method is judged.
