NORTH NORFOLK COASTAL EROSION Charles Lydon & Jonathan Staley

GEOLOGICAL BACKROUND Glacial depositions along region during the Pleistocene period Loose heterogeneous sedimentary rock south of Sheringham Chalk outcrop at Overstrand shown in wave-cut platform

GEOLOGICAL FEATURES These are examples of the cliffs at Happisburg Above shows the soft sedimentary rocks of Glacial Origin On the right shows the wave cut platform made of clay Coast retreating at 5m per year

PHYSICAL PROCESSES Wave erosion undercutting small cliffs e.g Happisburgh (<10m) Water Quickly erodes weak material and transports it away Steep cliff face maintained Translational Failure in areas of larger cliffs (20m) Groundwater percolates through loose gravels and ponds on top of impermeable clay P.W.P increases Shear strength decreases

HUMAN USE Large population living in coastal towns of Cromer and Sheringham Beaches Provide tourist industry in area, feeding the local economy Lots of static caravan sites in cliff top locations Bacton Natural Gas Terminal supplies lots of the country’s natural gas, therefore industrial importance Cliff erosion not only a threat to the local communities of North Norfolk but also to the national economy Therefore must be managed and controlled

ALTERNATIVE APPROACHES Beach Nourishment Managed Retreat Sea Walls Groynes Breakwaters – permeable or detached Maintaining spits Soft Engineering

SHERINGHAM – Hard Engineering Important business/shopping/ tourism centre Sea wall constructed in 1994 costing £6.4mil Earlier defences reached end of life Metamorphic rock imported from Norway

HOLME – Soft Engineering Sea levels increasing and area is low lying (all >50m a.s.l) Main defence is fragile sand-dune ecosystem Back of the dunes were planted with Corsican pines & Marram grasses Beach Nourishment attempted in 90’s but proved to be ineffective Experimental protection work showing gabions, chestnut fencing and conifers

HAPPISBURGH Managed Retreat Under current N.N.D.C. Shoreline Management Plan , Happisburgh is designated as a coastline where a policy of MANAGED RETREAT is in operation.  Erosion seemingly accelerates and properties disappear   The original 1950's sea defences with wooden revetments ,wooden groynes and steel piling have not been maintained Hydraulic action by waves behind the steel piling has undermined the sea wall