The Problem

According to estimates in 2009 the total length of the World’s coastline is 809,000 kms (approx. 500,000 miles). ⁽¹⁾

The average land elevation is 840m. The average sea depth is estimated at 3,796m. If the land were leveled out, it would be covered entirely by the sea to a depth of 2,686m. ⁽²⁾

Water is also dense (1m³  weighs around 1 ton) and can be abrasive – it is even used for cutting metals. Waves do cut into rock faces and cause cliffs to collapse.

The world’s coasts are the interface between land and sea, places where water is in constant motion being driven by wind, gravity and other forces; places where there is a constant attrition of the land by the water. There are places where particles carried in the water from elsewhere are deposited and where accretion may occur, and there are places where seismic upheavals occur and new land is created, but the vast majority of locations are subject to attrition and erosion. It is the process of movement towards equilibrium – the leveling of the land by the ocean.

Although it appears no studies have been done to determine the total area of land lost each year to the sea, logic dictates that it far exceeds the area created by accretion. Much publicity has been given to the potential land loss from rising ocean levels: very little has been given to the actual global loss of land through erosion. Of course, there are many local stories of collapsed cliffs, lost farms and properties claimed by the sea, but these occurrences have not been aggregated to present a global view. However, as there appears to be no shortage of local stories, it would be natural to assume that there is a significant global problem.

A large proportion of the human race lives by the side of the ocean. Moving them is not a realistic option, either politically or economically. Some individuals may be persuaded to build their houses elsewhere but millions want to live at the Oceanside, despite the potential for catastrophe. The hope for these people (if not for much of mankind) is that coastal engineering can make them safe. Those (non-interventionists) who assert that coastal processes are a natural phenomenon and should be left for nature to take its course are either blind to reality or guilty of a lack of care in their children’s’ future.

Andrew Cooper’s comment, “Engineering solutions to coastal erosion are often damaging, often don't work and usually cost a lot", is quite correct, but it does not mean that the solutions should not be tried. Anyone who works for any period of time in coastal engineering and other related marine professions soon realizes that the diversity of conditions encountered in locations where engineering solutions may be required dictates that there cannot be one clear and specific solution: what works in one location sometimes does not work in another even if the observed parameters are similar. But there are also many examples of where proposed solutions have worked and erosion has been prevented.

For a view of the confused state of the industry (if it can be called such) one needs only to look at the Coastal News Today website where dozens of examples of current beach replenishment projects, dredging projects and other coastal engineering projects primarily along the US East Coast, are published. Billions of dollars are spent, often for short term results. It is not uncommon to read of multi-million dollar replenishment and other projects, the benefits of which disappear in one or two seasons – a clear case of erroneous engineering solutions and a waste of good dollars.

The problem for the client is finding the correct solution, or an engineer who can be relied on to propose a viable solution for the location, not simply push a solution he has used elsewhere and is comfortable with. However, it would seem that every engineer has a different idea and a different solution. Much more research is needed and much greater sharing of information and exploration of options for solutions is essential to prevent looming disasters.