A CASE STUDY OF COASTAL EROSION & MANAGEMENT BARTON ON SEA A CASE STUDY OF COASTAL EROSION & MANAGEMENT

Geological Background Soft permeable Sand & gravel at the top of the cliff overlies soft Impermeable Clay at the base of the cliff. During heavy rainfall water gets trapped in the cliff & lubricates weaknesses resulting in rotational slumps. Wave attack at the cliff foot removes / undercuts the cliff, triggering more slumping.

Slumping There is much evidence along this stretch of coastline that the cliffs are slumping rapidly. The waterlogged clay can be clearly seen. The slumps pond back water further lubricating the clay.

Slumping Slumps in their early stages in the sand overlying the clay

Cliff Face Processes Gullying in the sand. Surface water has flowed down the cliff face creating these small channels

Cliff Face Processes 2 More evidence of Gullying, Note sand washed down the slope.

Cliff Face Processes 3 Natural processes are not the only processes operating on the cliff face. People accessing the beach have caused large amounts of human erosion.

Cliff Face This shows the steepness of the cliffs. This makes them very unstable as they can not support their own weight.

Cliff Erosion These building foundations clearly show the rapid erosion being undergone on these cliffs

Cliff Top Not long before this little chap goes over the cliff!

Land Use Behind these cliffs is the little town of Barton. These buildings are getting closer to the edge!

Land Use The sea front – the cliff top is on the right, this part of Barton has many years left yet before it comes under threat, some places are not so lucky

Land Use

Processes Summary

Rip Rap / Rock Armour These large boulders have been placed at the foot of the cliff to protect the cliff foot from wave attack.

Rip Rap / Rock Armour These boulders are needed because there is very little beach at Barton & the waves come upto the cliff foot at high tide.

Rip Rap / Rock Armour There is little beach because a large groyne built further along the coast at Hengistbury Head has trapped all the sediment that would have formed Barton’s beach. The rest has drifted off.

Long Groyne, Hengistbury Head This groyne built by Bournemouth Council in 1937 was designed to build up a beach. It has been successful & a wide beach has formed This sediment no longer reaches Barton, this has accelerated erosion at Barton

Rock Groyne This groyne has been constructed to trap what little beach Barton has

Rock Groyne You can see that sediment is building up against the groyne & forming a beach, to help protect the cliffs

Rock Groyne On the right hand side the beach has built up On the left hand side there is less material.

Rock Groyne Beach in the foreground The coastline is set back beyond this groyne – erosion due to a lack of beach.

Cliff Re-Grading As well as cliff foot defences there are cliff face defences. The cliff has been re-graded to make it shallower, therefore more stable & less prone to mass movement.

Cliff Re-Grading Vegetation planted on the re-graded slope helps to further stabilize the cliff The beach huts have some defence!

Cliff Re-Grading / Drainage Below these stones are drainage ditches / pipes which remove excess water from the cliffs & therefore reduces the lubricating effect.

Cliff Re-Grading / Drainage Beneath the stones are plastic sheets that stop rainwater infiltrating into the cliffs.

Cliff Drainage This mesh is part of the layer underlying the stone cover.

Cliff Face Overview Re-grading Drains Plastic sheeting Vegetation replanting

Lower Cliff Overview Rip Rap / Rock Armour Rock Groyne.

Public Warnings These are a selection of public warning signs indicating that there is a major problem in the area.

Management Overview This roadway was constructed to allow machinery to access the cliffs, so as to construct the defences. It also allows tourists to access the beach – important to the local economy

The Future