In quiet water areas, such as bays, wave energy is dispersed, so sand is deposited. Areas that stick out into the water are eroded by the strong wave energy that concentrates its power on the wave-cut cliff (Figure below). The wave erodes the bottom of the cliff, eventually causing the cliff to collapse.

As waves reach shallow water near the ocean shore, they begin to break. As the breaking waves hit the shoreline, their force knocks fragments off existing rock formations. And in Deposition, waves carry large amounts of sand, rock particles and pieces of shell. At some point, waves deposit the material they carry.

Deposition occurs when a river loses energy. When rivers flood the velocity of water slows. As the result of this the river’s capacity to transport material is reduced and deposition occurs. This deposition leaves a layer of sediment across the whole floodplain.

The waves push material at an angle up the beach via the swash and it is then deposited on the beach. The backwash will then collect the material and pull it down the beach in a vertical direction back out to sea. Another wave will then collect that material and carry it obliquely towards shore again.

If the swash is stronger than the backwash (constructive wave), some of the sediment carried in the wave will be left behind to build up the beach. This means that the beach increases in size. If the swash is weaker than the backwash (destructive wave), very little sediment is carried up the beach.

They are created in calm weather and are less powerful than destructive waves. They break on the shore and deposit material, building up beaches. They have a swash that is stronger than the backwash.

Breakwaters are barriers built offshore to protect part of the shoreline. They act as a barrier to waves, preventing erosion and allowing the beach to grow. The dissipation of wave energy allows material carried by longshore currents to be deposited behind the breakwater. This protects the shore.

Natural disasters and shoreline erosion are two of the main threats that coastal communities face. Such communities are particularly vulnerable to hurricanes and tsunamis, and as more people move to the coast, the potential of such events causing catastrophic loss of life and property damage also rises.

Prevent erosion of higher shoreline bluffs by:

1. Retaining moisture-absorbing vegetation on the bluff.
2. Diverting surface runoff away from the bluff (including rain gutter outlets).
3. Reducing runoff rate toward the bluff.
4. Minimizing paved areas that increase runoff.
5. Limiting ground water flow toward the bluff.

All coastlines are affected by storms and other natural events that cause erosion; the combination of storm surge at high tide with additional effects from strong waves—conditions commonly associated with landfalling tropical storms—creates the most damaging conditions.

Techniques for steep slopes include wood retaining walls, interlocking concrete blocks, rock retaining walls, riprap (loose rock) areas, and terracing. If you choose wood, make sure the wood is treated with a wood preservative to prevent rotting.

Beaches are virtually nonexistent in places. Man-made techniques such as beach nourishment—whereby sand is dredged from off-shore sources and deposited along otherwise vanishing beaches—may slow the process, but nothing short of global cooling or some other major geomorphic change will stop it altogether.

Coastal erosion may be caused by hydraulic action, abrasion, impact and corrosion by wind and water, and other forces, natural or unnatural. Also abrasion commonly happens in areas where there are strong winds, loose sand, and soft rocks. The blowing of millions of sharp sand grains creates a sandblasting effect.

Coastal areas have been changing with erosion and sand movement for ages. It becomes a problem when human activity speeds up erosion, or when buildings and roads are close enough to the ocean to be damaged. In these cases, beach erosion can cause flooding, and can even make whole buildings collapse.

There is a general consensus that human activity, mainly dam and reservoir impoundments on local rivers, caused coastal erosion (Feng, 1997; Feng et al., 1999; Huang and Yu, 1996; Yang et al., 1994). In addition, storm surges also considered to be a factor in beach erosion in QHDC (Yang et al., 1994).

The bare areas of a field are very susceptible to erosion. Without anything growing on them, the soil is easily picked up and carried away. The fields also experience more erosion in the winter if no plants are growing on them and they are just left as bare soil.

Sand and Coral Mining, and Maintenance Dredging Coral mining and other means of spoiling the protective coral reefs, for example, fishing by the use of explosives or pollution, will also cause coastal erosion and beach degradation.

However, human activities can also strongly influence the propensity of landforms to erode. For example, the construction of coastal structures (such as breakwaters, groynes and seawalls) can lead to changes in coastal sediment transport pathways, resulting in erosion in some areas and accretion in others.

Human actions that lead to the destruction of dune grasses and the disturbance of coastal landforms promote increased erosion and movement of beach materials. Off-road vehicles and foot traffic on sand dunes compact sand, destroying plant roots and animal burrows.

Running water is responsible for most desert erosion. Flash floods and mudflows are common because there is no vegetation to hold back the runoff. Slopes are steeper because, due to the lack of water in the soil, mass wasting is reduced in importance.

Human activities in coastal areas have affected many of the natural environmental processes there. This has led to a wide range of issues including a loss of biodiversity, high levels of pollution, erosion, and rising sea levels due to climate change. In fact, coasts are one of the Earth’s most threatened environments.

Because coasts are dynamic, or constantly changing, they are important ecosystems. They provide unique homes for marine plants, animals, and insects. Coasts help us understand natural events, such as weather and changing sea levels. During storms, coasts are the first places to be flooded.

A coastal zone is the interface between the land and water. These zones are important because a majority of the world’s population inhabit such zones. Coastal zones are continually changing because of the dynamic interaction between the oceans and the land.

Pollution, human alteration, and impacts from climate change can harm the sensitive beach environment that supports a variety of plants and animals. Beaches can be altered or destroyed if we don’t properly protect our beaches and learn to enjoy them without harming them. On this page: Pollution.