Environmental Engineering Reference
In-Depth Information
revealed differences linked to the main coastal problems of each country. In the
Netherlands, Denmark, the United Kingdom and Germany beach renourishment
projects typically form part of long-term intervention against coastal erosion and
protection against flooding. Most notably, in the Netherlands the impetus has been
to reduce the risk of flooding as a significant proportion of the land is below mean
sea level. By contrast, in Spain, Italy, Portugal and France renourishment pro-
jects are driven strongly by recreational considerations and the need for dry beach
width, which partly reflects the economic importance of recreation. In Spain ren-
ourishment has been used principally to protect property and sustain recreational
beach space.
In the Netherlands, Germany, United Kingdom and Denmark the need for
coastal protection against flooding has given rise to long-term beach renourish-
ment and monitoring strategies (Hamm et al.
2002
). The Netherlands in particu-
lar have long-term monitoring programs, with records of the position of dune foot
and mean high and low water levels going back until 1840 (Bird
1996
). After suc-
cessful beach renourishment projects in the 1950s, Dutch government policy has
been to maintain the coastline at its 1990 position, primarily using sand renourish-
ment projects to prevent coastal recession. The Netherlands has the most strate-
gic long-term approach to beach renourishment, with rigid design and legislation,
most commonly using the 'Dutch Method' (Sect.
4.4.1
, p. 79) but also experi-
HaskoningDHV
2009
; Stive et al.
2013
). The New Delta Committee, formed in
2007 to provide advice on the country's preparedness for mitigating flood risk
attributable to accelerated sea level rise in the 21st century, the annual sand ren-
ourishment volume for the Dutch coast should increase from around 12 to 80 mil-
lion m
3
/year (Kabat et al.
2009
).
Spain has used predominantly subaerial placement to increase dry beach width,
often without sea walls or groynes, while Italy, Portugal and France commonly
use such supporting structures. In Italy during the past 20 years about a hun-
dred beaches have been artificially renourished (Valloni and Barsanti
2007
). The
many small-volume projects (40,000-100,000 m
3
) are accompanied by several
larger scale beach renourishments, as at Pellestrina (4 million m
3
) and Cavallino
(2 million m
3
) near Venice, in the south of Italy at Paola (1 million m
3
) and on
the west coast at Ostia near Rome (1 million m
3
). Borrow material is commonly
sand and gravel and is almost exclusively from the sea floor (Barsanti et al.
2011
).
In Portugal the first beach renourishment was in 1950 at Estoril, near Lisbon, with
the deposition of 15,000 m
3
of sand (Hanson et al.
2002
). Despite this early use
of the technique, coastal protection in Portugal has often been based on hard engi-
neering structures (sea walls and groynes), generally built in response to emergency
situations. Beach renourishment has only been used on relatively sheltered beaches,
particularly on the Algarve coast, and generally with groynes to prevent downdrift
losses. An example is Praia da Rocha (Fig.
4.18
) (Psuty and Moreira
1990
; Psuty
et al.
1992
). At Vale Do Lobo on the Algarve coast, erosion resulting from updrift
construction of groyne fields and marina structures at Quarteira and Villa Moura
was offset by beach renourishment in 1998-1999, with deposition of 600,000 m
3
