Sand in sight

Germany’s most famous North Sea island is threatened with extinction. Every year Sylt gets a little smaller. The “Blanke Hans”, as the stormy North Sea is also called, gnaws ceaselessly at the island’s west coast. To stop the shrinking of Sylt, sand is now to be pumped from the seabed onto the beach.

A hundred years ago, the island’s inhabitants were already thinking about how they could protect their coast from the raging North Sea. Long rows of wooden piles, so-called groynes, were driven into the sea at right angles to the coastline. Intended as breakwaters, they unfortunately did not bring the desired success on Sylt. Beach walls and concrete monstrosities were also built in the sand to fortify the island. Unfortunately, they were not only ugly but also useless. The masses of sand continued to be washed away and partly stranded off the coast of Amrum.

Sylt is now hoping for a new coastal protection measure: sand flushing. Dredgers dig up sand off the west coast, which is pumped onto Sylt’s beach and distributed there. When the North Sea rages again, it will initially only take the flushed-up sand with it. The original coastline is to be preserved in this way. Presumably, the flushing will have to be repeated regularly to preserve the holiday paradise in the long run. One can only hope: “Trutz Blanke Hans!”

Ballad of Detlev von Liliencron (1844-1909)

The extent to which the North Sea raged and wiped out the settlement of Rungholt and other villages in the terrible Marcellus Flood of 1362 is described by the poet Detlev von Liliencron in his ballad “Trutz Blanke Hans”, first published in 1883, which roughly translates as “Defy the stormy North Sea!”

Dubai opens “The Palm Jumeirah

At midnight, Dubai welcomed its island “The Palm Jumeirah” with the largest fireworks display in the world. It took seven years to build the artificial island, which juts into the sea like a giant palm tree. Now the “eighth wonder of the world” is finished – in the middle of the Persian Gulf.

With the branching palm island, Dubai wanted one thing above all: to gain large beaches and many plots of land that lie directly on the sea. The shape of the palm tree was made for this. By all appearances, the developers’ plan has succeeded: Dubai’s coastline is now a hundred kilometres longer. How the island construction will affect the environment and how stable it will be in the long run remains to be seen: New roads, villas and luxury hotels – everything here is built on sand.

It is a project of superlatives: in order to heave the fantastic island out of the water, 100 million cubic metres of sand were moved from the sandbanks off the coast and piled up. A wall of stones is to protect the artificial beaches from erosion. At peak times, 40,000 construction workers were at work every day. Thirty luxury hotels were built, over 1,500 villas with their own access to the beach. The construction of the island complex cost a whole 1.5 billion dollars.

“The Palm Jumeirah” is not the last construction project of its kind. The Emirate of Dubai is planning and building four more large-scale art islands. Their names: “The Palm Jebel Ali”, “The Palm Deira”, “The World” and “The Universe”.

New territory for the Maldives

Nowhere else do the inhabitants of Malé live so closely together. The capital of the Maldives is the most densely populated city in the world. To create space, the government began reclaiming new land as early as 1975. But the area was not enough. Therefore, sand was piled up on the neighbouring island from 1997 and a new city was founded: Hulhumalé. The island is at least two metres above sea level. That is a lot for the Maldives, because on average the coral islands in the Indian Ocean rise just one metre out of the water. Their low height poses a great danger: because of the expected rise in sea level, one metre more or less could become essential for survival.

Grote Mandränke

Friesland. In the night of 16 January, the waves crashed more than two metres high over the tops of the dikes. On the coast of North Friesland, 21 dikes broke. The devastating storm surge probably cost thousands of lives. Whole swathes of land and several villages in North and East Frisia were submerged in the sea.

The “grote Mandränke”, as the storm surge is called, wreaked terrible havoc on the North Sea coast. The low summer dikes could not withstand the destructive water masses. The floods swept away terps (inhabited hills) along with houses and people, leaving a landscape in chaos.

Nothing on the North Sea coast is as it was before. Large parts of the islands and Halligen between Sylt in the north and Eiderstedt in the south, the so-called “Utlande”, sank into the North Sea. The thriving settlement of Rungholt, a major trading centre on the island of Strand, was simply washed away, along with seven other communities on the island. The land is lost forever.

The disaster mainly affects the marsh farmers of the area. Thousands of people drowned in the floods, most of their fertile arable and pasture land was swallowed up by the waters. In the meantime, the devastating flood has been interpreted as a sign from God. He is said to have punished the people for their frivolity and extravagance with a storm tide.

Eyewitness account of a monk:

A Dominican priest witnessed the events of the night of the storm and reports on the terrible devastation: “In the night of Marcellus Day, at midnight, such a terrible storm arose that the most solid buildings as well as churches and towers collapsed and the thickest trees were blown down. It caused a flood that inundated the Westermarsch and also parts of East Frisia. Everywhere the dikes break, the cattle drown in the stables. People fight against the floods, but their struggle is completely futile. The immense masses of water sweep away everything in their path.”

Coastal protection and dike construction

The surf of the sea is constantly battering the coasts: it works shallow shore zones and steep coasts alike, reshaping them in the process. The power of the sea is particularly strong during storm surges, which can flood and erode entire coastal areas. Global warming increases this danger even more due to rising sea levels. In order to prevent destruction by the water as far as possible, people have been striving for coastal protection for a long time.

If you don’t want to dike, you have to give way!” This old adage speaks of the fact that on many coasts and also on river banks, the construction of dikes is necessary to protect the land from the water masses. Dikes are elongated structures with a special cross-section: they are flatter towards the water so that the waves can roll out slowly and the dike does not break so quickly. A dike should also be at least as high as the highest water level was. At the same time, it must be very stable. Its core usually consists of sand, over which soil is poured. Grass grows on its surface. The grass is to prevent the sand and earth from being washed away too quickly. Many dikes lie a little way inland, so that the sea can “let off steam” in front of them. Sometimes there is a lower dike in front of the main dike to stop small floods here.

From some coasts, a lot of sand is washed away by the surf. The coast of Sylt is one of them. If man did nothing, the island would be washed away by the sea over time. To prevent such sandy coasts from sinking completely into the sea, they are artificially filled up with sand. However, this method is complex and expensive and must be repeated at regular intervals.

Steep coasts are less threatened by flooding because the land behind them is higher. But the force of the water also wears away the rock here and gnaws away at the coastline. To slow down this process, rows of piles or concrete walls can be built off the coast. These structures are meant to break the waves and reduce the force of the surf

The sea shapes coasts

Wherever seawater meets dry land, we speak of a coast. Because the coast is exposed to the force of the sea without interruption, it is constantly changing. How strongly the water gnaws at the mainland depends on the strength of the rock, the height of the waves, the ocean currents and the tides.

Gentle ocean waves that wash sand and gravel onto the flat land heap up sandbanks and create a beach. The water further crushes the debris, reshaping the beach again and again. If waves and wind shift the sand sideways, a hook of sand grows into the sea. When this hook reaches the opposite end of a bay, the hook becomes a spit. Enclosed by the spit, a lake remains from the seawater: the lagoon.

But the surf does not only work the fine sand. It can even erode hard rock when it thunders with force against the cliffs of a steep coast. If the water drags broken-off pieces of rock with it, it grinds the rock further at the height of the waves: Cavities form. If the overlying rock collapses, receding bays and capes remain, reaching into the sea like arms of land. Sometimes only individual towers of rock remain in the sea, which are further worked by the water and eventually also collapse. The power of the sea is particularly strong during storm surges. They can extremely change the shape and course of the coast.

An eternal to and fro of fine sand and clay prevails on shallow tidal coasts. The alternation of low and high tide ensures that the material is washed up and away again and again. The result is a mudflat coast. The mudflats were washed up and deposited by the water and are covered by the sea at high tide. At low tide, channels appear in the mudflats – the tideways. The seawater flows through them, similar to a river bed, at low tide and back towards the land at high tide.

Land reclamation

The “Netherlands” does not bear its name for nothing. The country is very flat, a quarter of it is even lower than sea level. This is because the Dutch have reclaimed part of their land from the sea: Shallow areas of the sea were dyked and the area inside the dykes was pumped empty. The drained seabed, now called the polder, thus became the mainland, which could be settled and used for agriculture.

Another way of gaining land has to do with the tides. Due to the constant change of high and low tide, silt accumulates on the coast. On the North Sea coast, people use this natural deposit and accelerate it by building groynes. Groynes are rows of wood or concrete that protrude into the water and calm it. The flow of seawater at low tide is slowed down and the fine suspended particles in the water settle. Over time, the seabed becomes higher and after a few years a special plant can grow here: the Queller. With its roots, it fortifies the bottom and also holds back further silt. As soon as the alluvial soil is high enough, a dike is built in front of it: New land is gained. On the North Sea, land reclaimed from the sea is also called a koog. In the past, the shallow coogs were mainly used for agriculture. Today, the land is mainly used for coastal protection.

However, land can also be reclaimed independently of the tides. On some coasts, sand and gravel are artificially filled in to secure the coast or to create building land. In Dubai on the Persian Gulf, sea sand was piled up to create several groups of islands.

The government of the Maldives had islands expanded or new ones created with coral sand. For the island state in the Indian Ocean, coastal protection is a particular problem: a large part of the Maldives islands are not even one metre above sea level!

Waves and monster waves

Wind and waves – these two forces of nature belong inseparably together. Unlike the tides, waves are created by the wind. The wind glides over the surface of the water and pushes the water along. How high the waves get depends on the wind strength and on the distances over which the wind whistles across the water.

If the waves run up onto the land on the coasts, they become higher. This is because as the water depth decreases, there is less and less space for the water to move upwards. In shallow water, the wave is also slowed down at the bottom. The crest of the wave, on the other hand, tilts forward without braking and “breaks”. The swirling of the water in the air creates white whitecaps, the spray.

When an extremely strong wind blows across the sea, a storm surge occurs. Storm surges are particularly frequent in spring and autumn. With their force, they can cause severe flooding and completely change the shape of the coast. The North Sea coast with the German Bight is particularly at risk from storm surges. Because the North Sea is very shallow, the water here can pile up very high during a storm.

In addition, there are also individual particularly steep waves that are much higher than the waves in their vicinity. For a long time, such monster waves or “cavent men” were thought to be “sailor’s yarn”, i.e. exaggerated stories of adventure told by seafarers. However, satellite images and precise measurements can now prove that such monster waves really do exist. They can reach heights of up to 40 metres, posing a serious danger even to large ships. It is not yet clear exactly how they form. Presumably, they are formed by the coincidence of slow and fast waves, combined with ocean currents.

Unlike waves and monster waves, tsunami waves develop after earthquakes or volcanic eruptions. Tsunami waves can be devastating: In Japan, a ten-metre-high tsunami rolled over the country’s northern coast after a violent earthquake in March 2011. Thousands of people fell victim to the disaster.