Empirical Equations of Equilibrium within Tidal Inlets

This work develops a general approach to equilibrium assessment to determine the stability of a tidal inlet. This is achieved by establishing a universal empirical equation with the inclusion of all affecting parameters. Data were collected from a number of tidal inlets from a range of published material, and relationships between the parameters considered to be of importance in inlet equilibrium dynamics were derived through linear regressioii. The most significant of these were analysed through multiple regression to yield a general empirical equation with the inclusion of the important factors. The results show the intimate Imkage between these parameters. Relationships describing these are statistically significant to 99.5%. The smgle most important parameter in cross-sectional area adjustment and sand volume variation of the outer delta was shovra to be the mean maxunum velocity. The tidal prism, cross-sectional area, inlet discharge and the longshore drift were found to adjust to maintain a constant mean maximum velocity of ~1.02ms necessary to impart a critical bottom stress on the inlet bed. The inlet follows a tendency to increase its stability with increasing cross-sectional area. When this is greater than ~1914m2, the inlet attains natural equilibrium and "relatively good conditions" (Bruun, 1978)