Case study - Happisburgh Flashcards
Unintentional coastal change (30 cards)
1
Q
Which sediment cell?
A
NE Norfolk
- Part of sediment cell 3
2
Q
NE Norfolk - cliff material?
A
- soft sands and clays
3
Q
NE Norfolk cliff materal vulnerabilities
A
- wave attack
- rotational slumping
4
Q
NE Norfolk dominant winds
A
- North Easterly
- Significant sediment drift North to South
5
Q
Coastal management challenge?
A
- protecting one part slows rates of longshore drift
- starve sediment from beaches further down
6
Q
SMP proposal
A
- Managed repeat for areas of limited socio-economic value
- cause conflict - homes and villages lost to sea in near future
- Nearby towns protected by expensive engineering schemes
7
Q
Egs of protection / not protection
A
- Sea Palling
- Happisburgh
8
Q
Sea Palling coastal protection methods
A
- recurved sea wall
- stepped sea wall
-riprap - groynes
9
Q
Sea Palling past issues - why need to protect
A
- 1953 storm surge broke through sand dunes
- flooded large parts NE Norfolk
- ## Since 1953 protect Sea Palling to protect Norfolk Broads
10
Q
Updrift of Sea Palling
A
- Groynes placed at Eccles to trap sediment
- Produces wide, open beaches
- Reduces sediment reaching beaches further south (Sea Palling)
11
Q
Sea Palling development of defences (sea wall)
A
- 1953 Sea wall built in front of sand dunes, ensure inland area protected from storm surges
- Storms reach the sea wall and undermine it
- 1991 Sea Palling beach management strategy
- 1992 strategy implemented to ensure long term protection
12
Q
Sea Palling defences (boulders)
A
- 1992 over 100 000 tonnes of boulders put in front of sea wall
- Prevent undermining
13
Q
Sea Palling defences (beach replenishment)
A
- 1992 1 million metres cubed of sand
- Cover boulders and widen beach
14
Q
Sea Palling defences (offshore bars)
A
- 1992 set offshore bars, parallel to coast, act as breakwaters
- mini riprap islands - gaps left between to allow longshore drift to create tombolos, sediment builds up behind, connects them to the beach
- constructed to break waves before reach beach
- absorb wave energy during storms
15
Q
Sea Palling defences impact downdrift
A
- sediment flow south from Sea Palling reduced by defences (particularly bars)
- Necessitate beach replenishment at Waxham
16
Q
Happisburgh - coastal process concerns
A
- erosion - soft cliffs
- increasing numbers of homes and businesses at risk
17
Q
Happisburgh - historical erosion
A
- 1950’s timber defences destroyed by waves
- cliff face left open to attack
18
Q
Happisburgh 1990’s
A
- LA identified need to replace existing defences to protect village
19
Q
Happisburgh 2001
A
DEFRA proposal:
- rock groyes, encourage sediment accumulation
- create wider beach in front of cliffs - absorb wave energy during storms
- rejected on financial and technical grounds - land and buildings left at risk of erosion
20
Q
Sea Palling SMP statement
A
- Due to the considerable assets at risk and the uncertainty of how the coastline could evolve, the policy is to hold the present line of defence. This policy is likely to involve maintainance of the existing sea walls and the reef structures, replacing groynes as necessary and continuing to renourish beaches with dredged sand’.
21
Q
Happisburgh 2002 Emergency Measure
A
- North Norfolk District Council ordered provision 4 000 tonnes boulders
- Create rock bund at cliff base
- Seen as temporary measure to slow erosion until permanent measure found
22
Q
Happisburgh 2006
A
- SMP proposed no active intervention
- Leave the coast to retreat
23
Q
Happisburgh 2007
A
- Temporary rock bund extended
- with £50k raised from local campaign
24
Q
Sea Palling SMP recommendations
A
No loss of:
- property and land use
- nature conservation
- landscape
- historic environment
- amenities or recreational use
25
Happisburgh SMP statement
'It would not be appropriate to defend Happisburgh due to the impact this would have on the shorline as a whole as coastal retreat in time would result in development of this area as a promentary, making it impact significantly on the transport of sediment to downdrift areas. Although there are implications such as loss of residential properties and amenities at Happisburgh, these are not sufficient to economically justify building new defences along this frontage. Existing rock bund will continue to have a limited effect on the retreat ratio in the short term (5 to 10 years) but will not prevent cliff erosion'.
26
Happisburgh - local people's views
want a clear strategy Happisburgh defence strategy
- government money to be spent protecting their coast
- number of important heritage sites will be lost forever
- problem is beach development here starves other places downdrift
- H is thriving community, has amenities and tourism, worth saving
27
Happisburgh - impact to local people
- retreat is fast, person buying house a row back is now 20m from sea
- value of house prices fallen
- recent SMP means larger towns protected, villages like H left to fall into the sea
28
Happisburgh SMP implications - 20 years
By 2025 loss of:
- less than 15 properties
- clifftop caravan park land
- coastguard facility
- grade 1 agricultural land
- continued exposure of SSSI cliffs
- little or no beach
access maintained
no clifftop heritage site lost
29
Happisburgh SMP implications - 50 years
By 2055 loss of:
- between 15 and 20 properties
- clifftop caravan park land
- grade 1 agricultural land
- SSSI cliffs
- grade 1 St Marys church, grade 2 manor house erosion risk
- beach present but loss of existing access
30
Happisburgh SMP implications - 100 years
By 2105 loss of:
- 20 to 35 properties
- caravan park land lost
- 45 hectares grade 1 agricultural land
- SSSI cliffs
- church, manor house lost
- beach present, existing access lost
