WIT Press

Coastal Cities: A Discussion Of The Flooding Potential Of Coastal Cities In This Century


Free (open access)

Paper DOI






Page Range

75 - 83




953 kb


O. T. Gudmestad


There are several causes for occasionally increased water levels in major cities. Such incidents are normally associated with large storm situations. The consequences could be huge damage, public disarray and the loss of many lives.

Further details of the situations are discussed with an emphasis on:

• the sinking caused by ground water extraction;

• the effect of rising sea levels;

• climatological changes caused by global warming leading to intense low pressures and frequent high waves;

• extreme storm surges, combined with high tides, leading to an increase in the average water level, which, combined with large waves, will overtop most present dikes.

The discussion is focused on remedial measures to sustain the inflow of water and limit accidental and economic damage. Emphasis is put on:

• safeguarding critical infrastructure with the building of local protection barriers against inflow of water to metros, for protection of vulnerable buildings and for forced blocking of dangerous situations on roads and railways;

• evaluating the effect of beach erosion on critical infrastructure, including buildings, with an assessment of strengthening strategy and the use of plants to limit erosion;

• the need for preparation of dikes to protect cities or parts of these from high water effect;

• the efficiency of floating protection barriers to reduce the effect of waves while accepting the increase in high tide and storm surge effects;

• discussing the safety level obtainable with realistic funding.

We do, however, also point to the fact that flooding has occurred in the past and that we shall expect damaging flooding in the future, regardless of the measures taken to protect assets against such situations. Then, the authorities are left with few alternatives but the evacuation of the population and acceptance of the infrastructure damage. A strategy of limiting the consequences of flooding might be more successful in the future compared to limiting the flooding situations.


storm surges, sea level rise, flooding, protection barriers, dikes