A Treatise On The Principles And Practice Of Harbour Engineering

24 HARBOUR ENGINEERING of the range of accretion, and connected with the shore by means of open- work jetties, as exemplified at Amager, Snogebæk and Hundested (page 41). Columnar structures offer little, if any, perceptible obstruction to current flow, and consequently should not give rise to a deposit of any appréciable extent. Whatever shoaling takes place abreast of the outermost and solid Fig. 17. portion of the pier, should be, and generally is, comparatively insignificant. The breakwater at Zeebrugge has been designed on these lines, as also the pier at Rosslare on the east coast of Ireland. Unfortunately, for the general application of the principle, a disposition of the same kind adopted at Ceara harbour, in Brazil, has proved strikingly unsuccessful, and has entailed consequences disastrous to the port. The entire harbour is blocked with Fig. 18. —Salina Cruz Harbour. Effeot of initiatory breakwater operations. Note. —The design was subsequently modified. sand (fig. 19), despite the faet that an openwork viaduct lies between the breakwater and the shore. Land water entering the sea at any point is deflected by tidal currents, where they exist, to each side alternately, with the result that with the coastal sediment there is a tendency to shoal at some short distance outwards, forming a bar of various contours. With a strong wind and littoral current in one prédominant direction, there will most likely be produced, in addition