262
R.H. Charlier and Chr. P. De Meyer
3.2.2
Bournemouth, Dungeness and Portobello, U.IC
In Bournemouth, construction of a sea-wall cut off the sand supply from
neighboring cliffs. Beach nourishment was decided upon to remedy the situation.
In this case cost effectiveness of beach renourishment showed that the final cost
per running meter of beach amounted to about q- ll6/meter (+ 35.7/fl) (1975)
compared to a conventional sea-wall construction incorporating cut-off steel sheet
piling at 4- 628/meter (± 193/ft) (1975) 23.
A successful example of beach nourishment in conjunction with groines has been
carried out here where indigenous beach sand had a mean diameter of 0.2 mm.
Material from a nearby offshore site having a mean size of 0.4 mm was dredged
and pumped on the beach. Although some losses of beach occurred over the
years, the scheme was cost-effective. An important pleasure beach was restored
and the coastal defences were improved.
Using trailing hopper suction dredgers beach rebuilding material was pumped
ashore. Some 110,000 m 3 (144,100 cu.yd) of sand were placed within 200 m (656
fi) of the shore.
At Dungeness, in Kent, beach material is dredged in surplus areas and spread
where the beach is eroding, thereby balancing the sedimentary budget (cf. chapter
nI).
At Portobello near Edinburgh, Scotland, replenishment of the beach occurs in ten
year spans. The results are satisfactory but some question whether this is
sufficient.
3.2.3
Silt and Langeoog, F.R. Germany
The projects at Silt and Langeoog (Germany) considered construction of a sand
spit (refraction groin) as adequate coastal protection. Under wave action the sand
groin moves shoreward feeding the adjacent beach. The orientation of the sand
groin has to correspond with predominant wave direction.
Sea floor sand was dredged to rebuild beaches on Silt which had been given
earlier a protective system of jetties and tetrapod barriers.
R.H. Charlier and Chr. P. De Meyer
3.2.2
Bournemouth, Dungeness and Portobello, U.IC
In Bournemouth, construction of a sea-wall cut off the sand supply from
neighboring cliffs. Beach nourishment was decided upon to remedy the situation.
In this case cost effectiveness of beach renourishment showed that the final cost
per running meter of beach amounted to about q- ll6/meter (+ 35.7/fl) (1975)
compared to a conventional sea-wall construction incorporating cut-off steel sheet
piling at 4- 628/meter (± 193/ft) (1975) 23.
A successful example of beach nourishment in conjunction with groines has been
carried out here where indigenous beach sand had a mean diameter of 0.2 mm.
Material from a nearby offshore site having a mean size of 0.4 mm was dredged
and pumped on the beach. Although some losses of beach occurred over the
years, the scheme was cost-effective. An important pleasure beach was restored
and the coastal defences were improved.
Using trailing hopper suction dredgers beach rebuilding material was pumped
ashore. Some 110,000 m 3 (144,100 cu.yd) of sand were placed within 200 m (656
fi) of the shore.
At Dungeness, in Kent, beach material is dredged in surplus areas and spread
where the beach is eroding, thereby balancing the sedimentary budget (cf. chapter
nI).
At Portobello near Edinburgh, Scotland, replenishment of the beach occurs in ten
year spans. The results are satisfactory but some question whether this is
sufficient.
3.2.3
Silt and Langeoog, F.R. Germany
The projects at Silt and Langeoog (Germany) considered construction of a sand
spit (refraction groin) as adequate coastal protection. Under wave action the sand
groin moves shoreward feeding the adjacent beach. The orientation of the sand
groin has to correspond with predominant wave direction.
Sea floor sand was dredged to rebuild beaches on Silt which had been given
earlier a protective system of jetties and tetrapod barriers.