More than 70% of the earth’s shorelines are retreating due to rising sea levels. As shorelines move further inland, structures located on or near the coast may be destroyed. The appearance of a beach and its potential for recreational use may suffer.
Built-up areas have an increased need for protection against the erosion and scour which go along with rising water levels. Scour means a localised loss of soil often situated around underwater foundation elements such as piles, quay walls, etc.
Erosion is the action of surface processes such as water and wind displacing soil aggregates from one location to another. There are various types of erosion, including splash, sheet, rill, gully and stream channel erosion.
Horizontal soil pressure on quay walls can lead to serious failure modes and requires attention during the design phase. Concrete element block walls are often used to create quay walls, but they may be subject to deterioration when the blocks are reinforced with steel bars.
Dykes are essential structures to protect us from floodings. By definition they are built on weak soils which will cause differential settlements. Erosion becomes a risk when water levels are high and dykes are under heavy attack from waves for a period of time.
On coastal reclamation works, a thick layer of granular reclamation material is applied to form the new land profile. Variations in the depth of the weak soil and the differing depths of the reclamation mean that the finished reclamation profile may not settle evenly, and the presence of low permeability marine clays and silts will pose consolidation risks.
In deserts and arid areas close to the sea it is quite common for groundwater to move upwards. This is known as a ‘capillary rise process’ and brings dissolved salt in water close to the surface. Vegetation and marble pavements are seriously affected.