The Coast temporary junctions between land and sea are subject to change waves, currents, tides, biological processes, tectonic activity position changes as sea-level does

Sea level 18,000 years ago during last ice age

If sea level rises 60cm (20ft)

Red areas will flood in about 100-200 years Blue areas may flood over several centuries http://www.epa.gov/climatechange/effects/coastal/slrmaps_sealevelmap.html

Red areas would flood during spring high tides Over the next century, sea level is most likely to rise 55-60 cm along most of the U.S. Atlantic Red areas would flood during spring high tides http://www.epa.gov/climatechange/effects/coastal/slrmaps_ne_liny.html

Sea Level Rise Does Matter Superstorm Sandy produced record storm surge levels for locations in and around the NY City metropolitan region Sea levels have risen more than a foot in the New York City region since the Industrial Revolution. So what difference did this extra foot make for the citizens of New York City? Quite a lot. 6,000 more people impacted for each inch of rise! 70,929 more people and 30,551 more homes flooded. According to Dr. Ben Strauss, Chief Operating Officer and Director of the Program on Sea Level Rise at Climate Central

Beaches a zone of loose particles that covers part of the shore extends from a landward limit cliff, permanent dunes, seawall extends to the seaward limit where movement of sediment on and offshore ceases

Figure 10.1

Beach Profiles Steepness of beaches change with seasons and storms Summer and calm periods build up beaches Swash dominates (soaks into beach), less backwash Winter and storms erode and flatten beaches Backwash dominates, very little swash soaks in because beach is saturated)

Figure 10.2a Wide berm Steep beach face

Figure 10.2d Narrow berm Flatter beach face longshore bar

Seasonal Changes on a beach in California Figure 11.13 As seasons change, sand moves on and off Boomer Beach near La Jolla, California. Gentle summer waves move sand onshore (a), but larger winter waves remove the sand to offshore bars, exposing the basement rock (b). (c) The annual progression of sand onshore and offshore for a typical year. East Coast beaches are usually not as seasonally varied, but can change dramatically with the advent of nor’easters or tropical cyclones. Fig. 11-13c, p. 254

Before and After Sandy Long Branch, NJ Mantoloking, NJ

Before and After Sandy Cupsogue Beach, Westhampton, NY Fire Island Nat’l Seashore

Beaches exist in a delicate balance between accumulation and destruction Waves can transport sand onshore or offshore Longshore currents transport sand along the coastline

Figure 10.3b

Barrier Islands Are essentially large sand bars Protect the coast behind them Very unstable themselves

Figure 10.9 Tom’s River, NJ

Heavily developed barrier island: Ocean City, MD

Barrier Island Migration Figure 10.10

Figure 11.19 The migration of barrier islands. The heavy black lines south of Ocean City represent jetties constructed in the 1930s to protect the inlet. The jetties disrupt the north-to-south longshore current. As a result, Assateague Island has been starved of sediment and has migrated about 500 meters (1,640 feet) westward. Fig. 11-19, p. 258

Human Impact on Beaches Attempts to “save” beaches or property often fail or make matters worse

Figure 10.18: Groins

Figure 10.19 Shipbottom, NJ

Groin Field Cape May, NJ

Figure 10.20: Jetties

Figure 10.21 Santa Cruz Harbor, CA

Break water Santa Monica, CA

Designed to protect harbors from waves Can cause excessive erosion, requiring dredging to keep area stable

Figure 10.24: Seawalls

Alternative: Beach Replenishment

Figure 10.26

Figure 10.B: Relocation