Seaside views are popular, whether from a holiday cottage, an office building, a hotel room or a penthouse apartment. But those views need to be protected from the sea itself, which is eroding our coasts in many places, particularly due to the rising water level.
Since the last ice age, water levels have risen several metres, and in the hundred years that elapsed from 1900 to 2000, they rose an additional 16 centimetre. But they will not stop there, because scientists are expecting a rise of 40 centimetres or more in the 21st century, due to global warming.
Rising water level
"Once the rising water level is really acknowledged as a fact, the need for coastal protection and other measures is going to explode. The methods already in use today can be used, but it’s going to be very costly for society, and available funds will have to be prioritised so as to focus on areas with most at stake,” says Ole Juul Jensen, MarketDirector, Marine and Coastal Engineering at COWI.
COWI has been the consultant on some of the largest coastal projects both in Denmark and abroad. Here slope protection in the form of revetments, breakwaters and groynes, and beach nourishment have been combined. This is always done with a view to taking into account the rising water level.
"These days, all projects are based on increased design water levels of 30 to 40 centimetres. There used to be no focus on this, but it is now aprerequisite for any project," Ole Juul Jensen explains.
Combine methods
Today it is normal to combine several different methods when providing coastal protection. In the past, engineers relied mostly on groynes – a rock structure built perpendicular to the shoreline, but these resulted in leeside erosion, because they were not combined with beach nourishment.
Nowadays, beach nourishment is one of the most widely used methods throughout the world, and as such is often used in combination with either breakwaters, groynes or slope protection.By Gitte Roe Eriksen, cht@cowi.comPublished: 12.08.2008