tailieunhanh - Review of empirical relationships between inlet cross-section and tidal prism

Review of empirical relationships between inlet cross-section and tidal prism. This contribution compares some theoretical elaborations both qualitatively and quantitatively, confront these with US and Dutch empirical data and discuss their pros and cons for practical applications. | Review of empirical relationships between inlet cross-section and tidal prism Marcel . Stive1 and . Rakhorst2 Abstract Although other engineers had considered the relationship between tidal prism and inlet crosssectional area before it is O Brien who is usually credited for deriving the familiar relationship A aPm where A is the cross-sectional area relative to mean sea level and P is the spring tidal prism. The coefficients a and m vary from entrance to entrance however O Brien 1969 showed that for 28 US entrances a 10 4 and m are best-fit values applicable to all entrances when P is measured in cubic meters m3 and A in square meters m2 . Many different suggestions have been made in literature about the rationale behind the above relation. We explore here some theoretical elaborations inspired by this literature. The most popular elaboration is to express A in terms of the so named stability shear stress which in the approaches of Gerritsen 1990 and Friedrichs 1995 is defined as the shear stress needed to maintain a zero net transport gradient along the channel which is assumed close to the critical shear stress for sediment motion. However one may claim as posed by Kraus 1998 that this shear stress is not necessarily equal to the critical shear stress since a certain transport capacity is necessary to remove the sediment deposited by the littoral or alongshore drift. This contribution compares some theoretical elaborations both qualitatively and quantitatively confront these with US and Dutch empirical data and discuss their pros and cons for practical applications. 1. Introduction Although other engineers had considered the relationship between tidal prism and inlet cross-sectional area before it is usually O Brien who is usually credited for deriving the familiar relationship A aPm 1 where A is the cross-sectional area relative to mean sea level and P is the spring tidal prism. The coefficients a and m vary from entrance to entrance however O .