During severe storms, all gates will be raised to a nearly 45° equilibrium position by the introduction of compressed air, thus keeping a 2 m water level difference between sea and lagoon (see Fig. 107 and Fig. 108). Lateral refuge basins with navigation locks will allow the transit of small craft when the gates are raised. The closure is planned only for a few times a year and the water quality will not be affected.

Among the various studies and works within the Venice Project, the most traditionally coastal one is the general plan of interventions for the defence of the barrier islands (see Fig. 106). The narrow strip of land extends for 40 km and is interrupted only at the three port mouths of Lido, Malamocco and Chioggia. The thin
natural sandy barrier islands are eroding because of human activities, carried out since Medieval times, to control river flows and guarantee navigation. The situation has been worsened more recently by the reduction of river sediment supply, land subsidence and the construction of artificial inlet jetties.

Most of the lidos have been protected since ancient times with timber and rock seawalls and groynes (see Fig. 109). The new project includes different protected beach nourishment schemes. At Cavallino, the sand fill is contained only between newly designed groynes. At Pellestrina (see Fig. 110), where the steeper shore is more exposed to wave action, the groynes will be connected by a submerged rubble mound barrier parallel to the coast (in confined cells). The fine borrow sands will be dredged from offshore fossil beaches at M.S.L. -20 m. At Lido beach, new widely-spaced groynes will be built. The protection works were started in 1994.