German Federal Agency for Nature Conservation (BfN)


Sand and gravel extraction

Photo of a trailing suction hopper dredger in the North Sea. Photo: Hübner, Krause (BfN)
Photo of a trailing suction hopper dredger in the North Sea. Photo: Hübner, Krause (BfN)

Millions of tonnes of sand and gravel are needed as raw materials every year. But these mineral resources are becoming scarce on land, and our native seas face severe threat of exploitation as a putative inexhaustible source. Sand and gravel is still extracted in North Sea and Baltic Sea marine protected areas under extraction permits that predate the selection and notification of Natura 2000 sites.

The materials are mostly used in road building and for making concrete and mortar. Coastal defence works also use huge quantities of sand to safeguard dunes, beaches and even whole islands for the future. This affects large stretches of the Baltic Sea coast, an example being the Fischland-Darss-Zingst peninsula. A prime example in the North Sea is the Isle of Sylt, whose western shore is heavily eroded every year by winter storms. Several million tonnes of sand are taken from the sea each year for replenishment in such locations and sections of coast.

Building pipelines deepening ports and maintaining fairways for shipping also involve large-scale dredging of the sea floor. This kind of dredging is not usually associated with resource extraction, however.


There are two main methods of extracting sand and gravel:

In stationary extraction, an anchored cutter suction dredger excavates huge pits in the sea floor with depths of normally about 10 m and diameters of between 10 and 50 m.

In the second method, a trailing suction hopper dredger removes sediment from the surface of the sea floor. The dredger is pulled along the sea floor like a vacuum cleaner and leaves behind a furrow between 2 and 4 m wide and up to 0.5 m deep. This is the extraction method usually used in German waters.