Coasts - Theme 2 - HEC and LEC Flashcards
What are the charactoristics of a HEC
- High wind and waves
- erosion > deposition
- cliffs, wave cut platforms and headlands
What are charactoristics of a LEC
- Low energy winds and waves
- Deposition > erosion
- beaches, spits
How is sediment added to a cell from rivers
-depositied at deltas and estruies
How is sediment added to a cell from cliff erosion
-soft or unconsilidated rock gets eroded quickly
How is sediment added to a cell from longshore drift
-sediment transported from one end of the beach to th other
How is sediment added to a cell from wind
- sand can blow in
- sand dunes - accumulators and sources
How is sediment added to a cell from glaciers
-ice shelves holding sediment calve into the sea
How is sediment added to a cell from offshore
-waves tides and currents transport them in
What is a sediment cell
- where areas of sediment are largly self contained
- determined by topology and shape of coast
- in theory a closed system
- bounderies typically headlands and penisnulas
- 11 large in england and wales
Why are they theoretically closed systems
- only energy in and out
- high energy can change where sediment is - leave cell
What is a sediment budget
-balance between changes in sediment of what is leaving and entering the system
What does a sediment surplus mean
-more inputs
What does a sediment defecit mean
-more outputs
What does a balanced sediment budget mean
-dyanmic equilibirum
