السواحل وإدارتها
Geography · Key Stage 3 · The School
How the sea shapes the land
Four erosion processes: HYDRAULIC ACTION (water forced into cracks), ABRASION (rocks thrown at the cliff), ATTRITION (rocks knocking each other smaller), and SOLUTION (chemical dissolving). Where waves lose energy they deposit instead, building beaches and spits.
The landforms
A crack in a headland becomes a CAVE, the cave erodes through to make an ARCH, the arch collapses leaving a STACK, and the stack is undercut to a STUMP. That sequence is one of the most reliably examined things in the subject, and it is a story with a beginning and an end.
Defending a coast
HARD engineering — sea walls, groynes, rock armour — is effective, expensive, and often just moves the problem down the coast. SOFT engineering — beach nourishment, dune planting, managed retreat — is cheaper and works with natural processes, but accepts some land will be lost. Managed retreat is the option people find hardest, because it means deciding whose land goes.
Longshore drift moves sand along the coast, say west to east. Build groynes at Town A and sand piles up on the western side of each — Town A's beach grows. But that sand was on its way to Town B, which now receives less than it loses, so B's beach shrinks and its cliffs erode faster. A's problem was solved by moving it four miles east, which is why coastal management is now planned for a whole sediment cell.