NGOUDA DIONE SIMPLE wooden structures padded with coconut tree fronds are helping residents of Diogue island in southern Senegal to win back stretches of sandy beach from the Atlantic swells that threaten much of the West African coast. In some areas, half-submerged tree stumps and crumbling abandoned buildings show the impact of the waves - and the ongoing degradation of coastline, where 56% of West Africa's economic activity is generated and around a third of its population live, according to the World Bank. "The ocean was so far away that we used to hear it without seeing it," said Angele…