The common problems in coastal areas are flooding and erosion, and they have damaging effects on both people and the environment. They destroy property and take human lives.

Other consequences include retreating of coastline, forcing people to move or making the coast inappropriate for development.

Protection against flooding

As in rivers, the measures taken to prevent massive flooding by the sea are building dams and storm surge barriers.

These dams serve other purposes besides flood control as they provide the residents with sources of water.

Protection against marine erosion

There are various types of measures taken to protect the coast against marine erosion. The more common structures built are seawalls, breakwaters and groynes, constructed of wood, concrete or rocks.

Seawalls

A seawall is constructed on the inland part of the shore and parallel to the coast. It protects the shore by reducing the effects of strong waves.

Though seawalls are useful in protecting the coast from erosion, it can also be a cause of erosion.

This is because the backwash of the reflected strong waves erodes the beach at a faster rate, undermining the base of the seawall, causing it to collapse, requiring repairs or replacement.

Breakwaters

Another structure used to protect coasts is a breakwater, a structure that can be constructed at some distance away from the coast or with one of its end attached to the coast.

A breakwater built at a distance away from the coast protects the coast by breaking the erosive powers of the waves.

So, a zone of quiet water is formed behind the breakwater, where materials are deposited to from beaches. The zone of protected water can also be developed into a marina for yachts and small boats.

But, breakwaters can also erosion in the surrounding unprotected areas. As materials are deposited behind the breakwaters, there is a lack of deposition in the nearby area, subjecting them to marine erosion.

Groynes

Groynes are structures built at right angles to the coast so that they can trap materials and stop cut the process of longshore drift.

As materials are deposited on the side of the groynes facing the drift, beaches are built up on this side.

On the other hand, the other side of the groyne would be eroded at a higher rate as less materials are being deposited. Thus, beaches on this may disappear due to erosion by strong waves.

A possible solution to this effect is to build more groynes along the coast, however by doing this, the beauty of the coastline is spoilt.

Other measures

Besides building physical structures to reduce the effects of eroding waves, some other measures can be taken.

1. Spreading sand and placing boulders

Sand is spread on the beach so as to replace the eroded materials, helping to build up the beach. Boulders are placed on the coasts to reduce the powers of waves.

2. Growing vegetation

Vegetation is grown on the coasts to help stabilise the beach.

3. Regulations

Other than those mentioned above, one other measure that can be taken is to have regulations for coastal development, where the building of housing and resorts are monitored.