azza: in the worst-case scenario, the historic defensive wall will collapse.t of it already broke away, but we repaired that. if the wall collapses completely, the park will sink into the sea. reporter: beaches will also be protected with a wall of concrete blocks. cranes are gradually sinking the tetrapods into the sea, costing tens of millions of euros. it's a dangerous mission against the forces of nature. azza: we've often had to stop our work and start all over again because of storm surges. in another place, all our equipment was submerged by water. these are already enormous challenges because we're working in the sea, in severe weather conditions, especially in winter. reporter: in the city's narrow alleyways, residents are at the mercy of the sheer volumes of water. the small apartment of ahmed ramadan and his wife mansura was flooded four times last winter as the result of rising sea levels and heavy rain. the pensioners don't have enough money to keep repainting the walls, or even to move away. they make do with plastic tarpaulins and stones onto wh