Pevensey Bay - CASE STUDY

Question 1

Why does Pevensey Bay need protecting?

Answer 1

• within the area, 100,000 properties, some minor roads, one main road and a railway line
• 9000ha of grazing marsh
• a National Nature reserve that is part run by the Sussex Wildlife Trust + is a RAMSAR site
• Pevensey Levels attract many wetland birds and feature some nationally rare species of flowering water plant.

Question 2

How is Beach replenishment/recharge used at Pevensey?

Answer 2

• Following low tide, beach sediment is replaced by dredging it from the ocean floor and spraying it as a slurry back onto the beach from the dredger
• this material is moved by a bulldozer to create a wide beach.

Question 3

How is Beach recycling used at Pevensey?

Answer 3

-Two or three times a year, beach material is moved from the east of the coastal defence area and is deposited back on the western side by large dump trucks, thus mitigating the effects of LSD.
- Recycled tyres are used to protect the natural shingle barrier from erosion
- Recycled plastic used to strengthen some groynes.

Question 4

How is beach re profiling used at Pevensey Bay?

Answer 4

The beach is regraded by moving material back up the beach using a bulldozer to re-instate the beach crest.

Question 5

How are GPS monitoring surveys used at Pevensey Bay?

Answer 5

Twice a month a quad bike with a GPS reciever surveys the beach to produce a three-dimensional model of the shingle bank and beach.

Question 6

How is Groyne replacement used at Pevensey?

Answer 6

The 150 groynes used to protect the coastal area of Pevensey are being removed and replaced by a small number of strategically placed groynes.

Question 7

How is Bypassing used at Pevensey ?

Answer 7

• The Sovereign Harbour interrupts the west to east movement of sediment, causing it to accumulate as a beach against the Harbour arm.
• In the winter, trucks are used to transfer between 5,000 and 15,000 metres cubed of surplus shingle back to the west to replenish the bay.

Question 8

What are the advantages of beach replenishment?

Answer 8

1. the wide beach is able to absorb wave energy during storm events (preventing cliff erosion)
2. Inexpensive

Question 9

What are the advantages of Beach recycling?

Answer 9

1. Often used when conditions do not allow the dredger to operate close to the shore (an alternative method)
2. Replenishes the dynamic equilibrium

Question 10

What are the advantages of Beach reprofiling?

Answer 10

1. Reduces longshore drift and helps to preserve the beach
2. Prevents beach material from being lost from the higher part of the beach (prevents cliff erosion)

Question 11

What are the advantages of GPS monitoring surveys?

Answer 11

1. Helps to maintain the sustainability of the project - provides specific areas of focus for replenishment, reprofiling and recycling

Question 12

What are the advantages of Groyne replacement?

Answer 12

1. Creates a more open and attractive beach - high amenity value for the tourist industry

Question 13

What are the advantages of Bypassing?

Answer 13

1. Emergency supply of shingle available to be used in winter
2. Does not disrupt tourism as it occurs most commonly during winter.

Question 14

What are the disadvantages of Beach replenishment/recharge?

Answer 14

• Offshore dredging of sand and shingle increases erosion in other areas
• Dredging affects the marine ecosystem
• People may be prevented from using the beach for several weeks

Question 15

What are the disadvantages of beach recycling?

Answer 15

• People may be prevented from using the beach for several weeks
• Needs to be regularly repeated - can become expensive to hire equipment repeatedly.

Question 16

What are the disadvantages of beach reprofiling?

Answer 16

• Only works when wave energy is low
• Needs to be repeated continuously (can become expensive)
• Beach closed - impacting local people, tourists and businesses

Question 17

What are the disadvantages of GPS monitoring surveys?

Answer 17

• Expensive equipment required
• Does not hold the line only provides direction for soft engineering strategies.

Question 18

What are the disadvantages of groyne replacement?

Answer 18

• Less sediment trapped by groynes to accumulate on the beach - LSD not disrupted

Question 19

What are the disadvantages of bypassing?

Answer 19

• May damage the natural ecosystem developed on the beach and therefor any species which inhabit the beach
• People may have disrupted access to the beach
• increased risk of erosion near the Sovereign Harbour arm