Tetrapods on the Beach

Coastal protection by tetrapodsAlready in the middle of the 19th century, the inhabitants of Sylt started thinking about coastal protection. From 1867 so-called groynes were built in numerous places.These are wooden poles that are driven into the sea in long rows at right angles to the shore. These are primarily intended to break the waves and keep currents parallel to the shore away from the beach. On Sylt, however, they do not bring the desired success because too many cross currents bypass the groynes.From 1960, so-called tetrapods were also erected on the west coast beaches. These huge, four-footed concrete monsters lie at the foot of the dunes, but are far too heavy for the Sylt sand and sometimes sink into the beach. They cannot offer an effective measure for coastal protection either. Starting in 2005, these unaesthetic and useless buildings began to be removed.Since the previous methods did not help much, a completely new variant was started in 1972: sand replenishment. Dredgers remove sand from the open sea off the west coast and pump a water-sand mixture onto the beach. Here the mixture is distributed by bulldozers.The advantage of sand replenishment is that only the pre-washed sand is removed by the sea and the natural coastline is largely spared from erosion. However, the sand flushing must be repeated at regular intervals, depending on the intensity of the erosion even annually. The immense costs of this coastal protection measure are covered by federal, state and EU funds.