Book 6, Question 128
Why Do Sea Walls Sometimes Make Beaches Worse?
A sea wall is a hard barrier that protects buildings from waves. But a wall bounces wave energy back instead of absorbing it. That churns up the sand and carries it away.
From the book
Page from A Million Whys Book 6
More fun facts
- Waves bounce off seawalls, and that bounced energy wears away sand at the bottom of the wall.
- The bouncing waves can also wash sand away from the beaches next to the wall.
- Beach erosion means sand is carried off to deeper water or along the shore into bays and inlets.
- Some beaches lose only a few inches a year, but others lose much more.
- Waves, currents, tides and wind all wear away coasts, in different amounts in different places.
- Rising seas speed up the natural wearing away of beaches around the world.
Sources: National Park Service, Scientific American, NOAA Ocean Service, NASA Science
Questions kids ask
How can a seawall hurt a beach?
Waves bounce off it and wash away sand at its base and on nearby beaches.