The Wadden is a coastal region stretching from the north-west of the Netherlands through Germany to the west of Denmark. It consists of the Wadden Sea, large parts of which fall dry during low tide, and the Wadden islands (see below), a string of islands that shields this sea from the North Sea. (Images Ameland)

Wadden coasts can be found all over the world in moderate climate zones. In tropical areas similar tidal areas are usually overgrown by mangrove forests. The biggest wadden area in the world is the aforementioned Wadden Sea. Other wadden areas can be found in Europe at sheltered places along the English Channel, Atlantic coast of France and the North Sea shore of England. (hotels on the Wadden Islands)

Prerequisites
There are a lot of prerequisites to be met for a wadden area to form, which is why this geological form is quite rare. Important is the availability of a shallow coastline which slows down the movement of water and enable the down wash of sand- and clay particles. When there is a very gradual increase of the sea level these strata can envelop an ever larger area. The height difference before the coast may be no more than one meter per kilometer while the difference between high and low tide has to be more than two meters. A wadden area nevertheless needs to be protected from strong sea currents. In the Wadden Sea the islands form this protective barrier.

Nature value
The extraordinary circumstances in a wadden area enable a very rich but also very fragile flora and fauna. The shallow water is relatively warm and rich with sea bed life. The wadden offer food and a resting place for birds and sea mammals. This is why environmentalists give the wadden area a high priority.
Origins
During the last ice age, which ended approximately 12,000 years ago, the sea level was about 60 meters below the current level. Due to melting of the ice caps the sea level rose and the water submerged the North Sea. The current coast line was reached approximately 7000 years ago. Due to the tides large quantities of sand were transported to the coast. This sand piled up near rocks and behind vegetation. There a large and unbroken line of dunes originated which extended all the way from contemporary Belgium to the mouth of the river Elbe, where now Hamburg lies.

Around the beginning of the era the increase of the sea level diminished. The sea had however already found its way through the dunes transformed the lower country behind to the current wadden plains. The continuous tidal currents wore gutters and this way the Wadden Islands arose.

Conservation of the WestFrisian/Dutch coast
The dunes south of the Wadden Sea were also liable to this process, but man’s intervention prevented that the many storm surges changed the coast of the provinces North-Holland and Zuid-Holland into separate islands with wadden plains behind them. However, storm surges, around 1200, did break up the northern coast of Western Friesland into five island. Around 1600 four of these along the west coast had been again recovered, but Wieringen, to the south east of Texel, remained an island up to the 20th century.

Embankment of the wad
In Friesland and Groningen a lot of plans have been made to embank and drain the Wadden Sea. As a result the islands would become part of the mainland. Nature - and environmental movements have always been able to prevent this.

The only plan ever to be carried out was the construction of a dam from the Frisian Holwerd to Ameland, in 1872, on the then wantij which was not very successful. The dam already had so much storm damage shortly after construction started that already in 1882, the dam was given up. The dam has been almost entirely knocked off since that time, though there are, among other things to both ends, still some remainders to be found.

In the northern Wadden Sea building dams proves to be considerably simple. Nordstrand is now so much linked to the rampart by dikes that one can’t really call it an island anymore, and also Langeness, Oland, Nordstrandischmoor, Hamburger Hallig, Sylt and Rømø are all reachable by dams. Mandø is even reachable without a dam, by means of tidal road.

Development

Walking
The Wadden Islands are in continuous movement. The most important movement is the 'walking': the islands themselves are slowly but certainly moving from West to East. On the West side most of the islands disappear slowly in the sea and on the East side always larger sand-banks arise. This walking is also the cause is that most of the villages themselves are on the West side of their island. When they were founded generally they were situated in the center. In the course of the last centuries a lot of houses and even complete villages have already disappeared into the sea.

Hook shaping
The second movement is the hook shaping: along the sea breaches hookshaped sand ridges arise, which change form with the moving of the sea arm. By growth of these hooks new plates arise such as the Noorder - and Zuiderhaaks. Sometimes such a plate grows, originating where an island has been ‘walking’, and as a result of which that island recovers its lost area.

Types of ‘wadden coasts’
Research has shown that there are a limited number of possible types of wadden coasts. These depend on the circumstances on the spot, such as altitude of the tidal difference and average golf altitude.

In general it commonly applies that a large tidal difference in combination with a small golf altitude leads to a very ' open ' coast, without islands, with some sand plates and vast area with kwelders and wadplates.

When there is on the other talk of a large average golf altitude but a small tidal difference, a closed coast with very long islands (dozens km), with a lagoon with little to no wadplaten arises.

The following five categories wadden coasts are distinguished:

type of 1: tide difference is dominant; no islands, vast kwelders and range plains
type of 2: richels built by golves, sometimes ' primitive ' islands
type of 3: many sea breaches and (short) islands
type of 4: decreasing number of islands, longer islands
type of 5: golf altitude is dominant; long joined tightly barriers
(Source: M.O. Hayes, Barrier island morphology ash a function or tidal and wave regime. In: S.P. Leatherman (ed) Barrier islands, from the Gulf or Saint Lawrence to the Gulf or Mexico, Academic Press, 1979.)

The average golf altitude near Rottum amounts to approximately 1 meter whereas the average tidal difference amounts to over 2 meters. Follows that the Dutch/German wadden coast fall into type of 3, characterised many (short) islands and many sea breaches.

Islands
(from West to East)

Inhabited
Texel
Vlieland
Terschelling
Ameland
Schiermonnikoog
The Dutch islands have a surface of 405.2 km² and a total of 23,872 inhabitants.

Uninhabited
Noorderhaaks
Richel
Griend
Rif
Engelsmanplaat
Simonszand
Rottumerplaat
Rottumeroog
The names of all these places suggest this is the transition area between island and sand plate. Griend and Rottumeroog are generally considered as an island, the others are considered to disappear from time to time into the waves. The former island of Wieringen can be found at the top of noord-Holland, dead against the ‘Afsluitdijk’. (not mentioned on map).