34. Figure 20.16 Wave erosion caused by strong storms, Long Island, New York Coastal development makes erosion a problem
35. Sea-level rise makes the problem worse Studies show a 150x erosion multiplier for sea level rise on sandy shorelines. Hence, for a mean 0.24 m rise by 2050, beaches will recede 36 m (118 ft). ( Leatherman et al., 2000)
61. USGS Locations of three submerged sand deposit areas on the insular shelf of Puerto Rico Aerial photograph of the Escollo de Arenas, a subtidal sand and gravel deposit that extends some 6 kilometers north-northwestward of Punta Arenas on the northwest coast of Vieques Island, east of Puerto Rico.
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Notas del editor
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FIGURE 13.15 ( p. 354) Water moves up a beach face at an angle with the wave direction but returns directly down the beach slope. Sand picked up by the incoming wave is washed up the beach and is returned seaward a small distance further down the beach in the direction of the waves. Successive waves move sand progressively along the beach—a process known as “longshore drift” or “littoral drift.”
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FIGURE 13.18 ( p. 357) Seasonal variation in beach profile. (a) During summer, when waves are relatively gentle, the beach profile is steep, and one or more summer berms form immediately above the high-tide line. (b) Winter or storm waves, especially when combined with storm surges, reach farther up the beach and erode sand from the berm, moving the sand seaward to form one or more offshore bars. The result is a narrower flat-beach foreshore that is cut back to dunes or a winter berm left from periodic extreme winter storms. (c) When storm waves cease, the gentler waves return sand from the offshore bar to the beach, rebuilding its summer profile. If storms are strong in a particular winter, the beach may recede inland, and dunes may be somewhat lowered.
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