Because the coastal strip is the lagoon’s first natural defence against the sea. Erosion has progressively reduced the width of beaches to the point where they have disappeared altogether in some places as has a large part of the original dune belt. As well as mitigating wind action and intercepting wind-blown sand, this also has considerable importance from a natural history and landscape point of view. Together with the numerous towns and villages along the Venice coast, the lagoon is ever more exposed to the threat of the sea. This is why protection of the coastal strip has become vital and urgent and major reinforcement measures have therefore been implemented.

Because construction of new artificial beaches and the widening of eroded ones by nourishing the zones affected with sand is the most modern and effective measure to protect the coastal strip.
In the past, the coasts were protected by the construction of jetties, seawalls, groynes and offshore breakwaters, while today the most modern coastal engineering techniques attach ever greater importance to the role played by beaches for their ability to oppose and counteract the action of sea storms.

Specific rock structures have been designed to protect the new beaches from erosion by “retaining” and stabilising the sand spread or actually capturing part of the sand in transit suspended in the sea water.
Depending on the area concerned, these consist in groynes (rock structures perpendicular to the coast) or “containment cells” (consisting of groynes and a submerged breakwater parallel with the beach) designed to take account of local coastal drift and current conditions, the characteristics of the section of coast concerned and the configuration of the sea bed.
It is, however, impossible to completely eliminate erosive forces and the new beaches will therefore be subject to periodic maintenance. This will involve “reinforcement” with at least one per cent sand per year (ten per cent every ten years, given that maintenance will not be continuous, but periodic).