Constructive and destructive waves

Constructive and Destructive waves

• Destructive:
• ~ Weak swash, dominant back wash- material is coned from the beach and moved off shore
• ~ Shorter wavelenght in relation to their height
• ~ Occur over a short period but high in frequenct 12-14 a minute, often formed by local storms
• ~ Steeper beaches formed through stormy conditions (winter)
• ~ Materil moved from the top of the beach to the bottom of the beach. It can move all mateial and store in offshore bars during winter and replace in summer by constructive waves. Shingle can also be fixed above the high tide mark creating a stone beach
• Constructive:
• ~Dominant swash, weak backwash- material moved onshore, building the beach
• ~ Long, low waves- called swell waves
• ~ Occur over loner periods, longer wavelengths, lower frequency: 6-8 per minute, from far off shore (swell waves)
• ~ Wide sloping beaches, low gradient (summer)
• ~ Material is moved from the bottom to the top of the beach because of the strong swash. This produces berms aswell as a sereis of ridges and runnels (little depressions), run laterally to the beach