The main problem at the coast is the effect of storm floods.
Around 24% of Schleswig-Holstein lies in the flood prone area,
which is below 5 m in the west and 3 m in the east (Hofstede
and Hammann, 2000). At the North Sea coast, these areas
contain the main areas of high population and of high economic
value, which has resulted in the coastline being protected
with dikes. Hard structures such as dikes are not the only
protection measures used: beach nourishment is also carried
out on the barrier islands of Föhr and Sylt. This not only stabilises
the coastline of the islands but also provides protection
for the mainland as well as sandy beaches for recreation. The
Baltic Sea coast has fewer stretches of dikes because of its
natural protection system of beach walls and spits.