Coasts - Case Study - Sandbanks - Coastline Management Flashcards
Where is Sandbanks?
- Dorset
Who is responsible for managing the Sandbanks peninsula? (3)
- Poole Harbour Commissioners
- Poole Borough Council
- Environment Agency
What is the plan called to manage Sandbanks?
Two Bays Shoreline Management Plan (based on sediment cell covering Poole Bay and Christchurch Bay
What options does the Environment Agency currently apply strategies from? (3)
- Hold the Line (HTL)- maintain, sustain or improve existing defences
- Managed Realignment (MR)- existing defences moved to more sustainable positions, usually further inland
- No Active Intervention (NAI)- areas of low economic value and/or high environmental value are not protected
Why does Sandbanks need managing? (6)
- Large number of high value commercial properties (i.e. Sandbanks Hotel & Haven Hotel = both create employment/spending in local economy)
- Residential properties high in demand & command premium prices (4th most expensive in world per square metre)- e.g. large detached houses = + £10m // luxury apartments = + £2m
- Beach = major tourist attraction- e.g. Blue Flag award for water quality & gently sloping = safe safe for family swimming
- Provides protection/shelter from waves for Poole Harbour = popular place for water sports (i.e. wind-surfing, sailing, water skiing) & home to numerous yacht clubs & marinas (i.e. Salterns)
- End of peninsula = entrance to Poole Harbour (used by cross-channel ferries, catamarans & commercial ships)- LSD could cause harbour entrance to become clogged & shallow
- Climate change = sea level predicted to rise 0.6m here in next 100 years = flooding of properties // breach peninsula at lowest & narrowest point (2m above sea level & 50m wide at Shore Road and Banks Road) cutting off from mainland- est. £18m damage to residential properties in next 20 years if no management strategies applied
What strategy has been implemented to maintain a deep and wide beach?
Rock groynes
What do rock groynes do to maintain the depth & width of the beach?
Minimise movements of sediment along the beach at Sandbanks (by LSD) = prevents sediment from entering harbour entrance (keep access free to ships) & absorbs wave energy (reduces rates of erosion)
What would rates of erosion be without rock groynes?
About 1m per year
What other strategy is in use to conserve the beaches?
- Beach recharge
What is beach recharge?
Sand dredged from offshore is sprayed onto the beach (‘rainbowing’) adding to its size
How much does beach recharge currently cost?
£20/m3
What is a cheaper alternative to beach recharge? (3 + but…)
[2015 trial]
- Dumping sediment dredged from the harbour just offshore involves a much cheaper alternative (only £3/m3)
- Natural currents transport sand onshore where will help to build up beaches
BUT 2018 review = only 3% of the 30,000m3 sediment dumped off-shore had reached the beach after 18 months
- In total, + 3.5 million m3 sediment has been added to Poole Bay beaches
How has the management of Sandbanks been successful?
Sediment budget surplus on the beach (beach profile widened = can absorb more energy)- NB: important due to climate change and resultant sea level rise.
Unintentional impacts of management at Sandbanks (2)
- Dredging = deeper water in offshore zone = less friction = more energy (more erosion in future).
- Sediment deficit further along coastline (i.e. Burton Cliffs) = base of cliff unprotected = more susceptible to mass movement (slumping) = spatially limited success.
