4.a. Human activity intentionally causes change within coastal landscape systems. Flashcards
What organisations form the ‘Two Bays Shoreline Management Plan’?
Poole Harbour Commissioners.
Poole Borough Council.
The Environment Agency.
What sub-sediment cell does the ‘Two Bays Shoreline Management Plan’ cover?
The sub-sediment cell covering Poole Bay and Christchurch Bay.
What are the names of the three strategies applied by the Environment Agency to Sandbanks?
Hold the Line (HTL)
Managed Realignment (MR)
No Active Intervention (NAI)
Outline ‘Hold the Line’ as a strategy used in Sandbanks.
Maintain, sustain or improve existing defences.
Outline ‘Managed Realignment’ as a strategy used in Sandbanks.
Existing defences moved to more sustainable positions, usually further inland.
Outline ‘No Active Intervention’ as a strategy used in Sandbanks.
Areas of low economic value and/ or high environmental value are not protected.
How many rock groynes have been constructed in Sandbanks? What will this do?
11 rock groynes have been constructed in order to maintain a deep and wide beach.
This will minimise the movements of sediment along the beach at Sandbanks by longshore drift.
Other than stopping the movement of sediment, what other three things will the Sandbanks rock groynes do?
Restricts sediment from entering the harbour entrance, thereby keeping access free for shipping,
Absorbs wave energy
Reduces rates of erosion.
Without the 11 rock groynes recently constructed in Sandbanks, what would erosion rates be each year?
It is estimated that without this action, erosion rates would be about 1m per year.
What type of beach nourishment is happening in Sandbanks?
Sand dredged from the offshore is sprayed onto the beach, a process known as ‘rainbowing’, adding to its size.
How much does the ‘rainbowing’ of Sandbanks cost? What alternative has been trialled?
This currently costs about £20/m³.
However, a 2015 trial of dumping sediment dredged from the harbour just offshore involves a much cheaper alternative, costing only £3/m³.
How does rainbowing support beaches?
Natural currents will transport the dredged sand onshore where it will eventually help to build up the beaches.
What is a negative of rainbowing?
A review in 2018 suggested that only 3% of the 30,000m³ of sediment dumped offshore had reached the beach after 18 months.
In total, how much sediment has been added to Poole Bay beaches?
Over 3.5 million m³ of sediment.
What are the 6 main reasons for protecting the coast of Sandbanks?
Has a large number of high value commercial properties built on it.
Residential properties are in high demand and command premium prices.
The beach is a major tourist attraction. It has a Blue Flag award for water quality.
It provides protection and shelter from waves for Poole Harbour, which is a popular and safe place for water sports and yacht clubs/ marinas.
At the end of the peninsula is the entrance to Poole Harbour, used by cross-channel ferries and catamarans, as well as commercial ships carrying goods such as timber.
Climate change means that sea levels are predicted to rise here about 0.6m (mid-range projections) in the next 100 years.
