Frequently, when navigational channels are dredged along inland waterways, nearly circular spoil islands are formed of sand-sized material. Consider such an island on which the waves are only from the...

Frequently, when navigational channels are dredged along inland waterways, nearly circular spoil islands are formed of sand-sized material. Consider such an island on which the waves are only from the north along the axis of the waterway, as shown in Figure 8.36. Neglect any effect of the dredged channel onthe island.

Figure 8.36

(a) Sketch and discuss the littoral drift rose for this island (qualitatively).

(b) Sketch and discuss the evolution of this island with time. 8.6 The littoral drift rose for a particular area is given in Figure 8.37. Three shoreline segments are separated by Inlets A and B. (a) Quantitatively describe the sand budget at Inlet A.

Figure 8.37

(b) Quantitatively describe the sand budget at Inlet B.

(c) Two groins are constructed north of Inlet A, as shown in Figure 8.38. With diffraction excluded from consideration, how far should the groins be extended landward (b = ?) beyond the shoreline to avoid flanking before bypassing occurs.

Figure 8.38