Publication Date:
2018-12-13
Description:
Facing the predicted rise in global sea level, sandy shorelines are under increasing pressure. In order to counteract the loss of
material at eroding coastlines, beach nourishment is considered to be an environmentally friendly approach worldwide. This has
resulted in a rising demand for aggregates, which are frequently extracted from the seafloor near the coast. In order to explore the
long- and short-term morphological changes of such mining on the seabed, the largest extraction area in the German Bight
(Westerland Dredging Area, established in 1984) was investigated in this study. Several measurement campaigns were conducted
between the years 1994 and 2017 using a set of hydroacoustic techniques. The measurements revealed that up to 20-m-deep pits
with diameters of more than 1 km were dredged into the seafloor. The depressions caused by this sand mining are still detectable
more than 30 years later. Because of slope failures that mainly consist of fine sand, the formerly steep rims at fresh dredging pits
smoothed within a few months. However, after approximately 1 year, muddy sediments dominated the deposition. Since the
sedimentation rates are slow, a complete backfill of the post-dredging pits is likely to take many decades. A natural regeneration
towards the former seafloor conditions is only visible at the shallow rims of the oldest dredging pits.
Repository Name:
EPIC Alfred Wegener Institut
Type:
Article
,
isiRev
Format:
application/pdf
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