ABSTRACT:

The primary objective is to identify the physical mechanisms associated with the intrusion process by performing the controlled laboratory experiments. We use solitary waves and an undular bore for the study. The opposing current amplifies and slows the waves locally on the current, but the propagation speed is faster than the local Doppler effect due to the influence of the wave propagating in the flank of the current. At the channel mouth, the wave amplitude is enhanced due to the waveform altered by the current together with diffraction effects of the reflected waves from the adjacent shore. The leading wave of the undular bore is impacted by the opposing flow and transition similarly to the solitary waves. In contrast, the subsequent waves of the undular bore have a complex phase interference on the current that causes disconnection in the lateral wave formation across the breadth of the current. At the transition, the subsequent waves exhibit greater amplification than the leading one due to accumulated wave energy at the channel mouth. The intrusion of the undular bore against the current further enhances a rise in mean water level in the channel.