Velocity surges and asymmetry in tidal channels

Previous work on tidal dynamics in salt marsh creeks have shown that velocity and discharge exhibit well marked surges throughout the cycle as well as a flood-ebb asymmetry. Two general models of tidal dynamics are discussed: one assuming modification of tidal stage by the marsh channel, the second assuming that channels have a purely passive role. Using the second model a series of theoretical velocity curves are calculated using progressively more complex tidal approximations. The theory is tested using velocity data obtained from the Stiffkey marsh, N. Norfolk, England by Bayliss-Smith et al. (1978). The velocity curve can be predicted using channel morphometric and tidal stage data. The interaction between channel morphology and the velocity curve are considered: it is suggested that channel velocity curves may provide an indication of marsh morphological development.