Kolindsund (English: ''

Sound In physics, sound is a vibration that propagates as an acoustic wave through a transmission medium such as a gas, liquid or solid. In human physiology and psychology, sound is the ''reception'' of such waves and their ''perception'' by the br ...

of Kolind'') is a olindsund.odeum.com/ref> elongated lakebed on the

Djursland Djursland () is a 1,417 km2 hilly lowland peninsula in Denmark at the entrance to the Baltic Sea, between Denmark and Sweden in Northern Europe. Djursland protrudes into the Kattegat sea, as part of the larger peninsula of Jutland, which its ...

peninsula in

Denmark Denmark is a Nordic countries, Nordic country in Northern Europe. It is the metropole and most populous constituent of the Kingdom of Denmark,, . also known as the Danish Realm, a constitutionally unitary state that includes the Autonomous a ...

. It extends west, inland from the coastal town of

Grenå Grenaa (or Grenå) is a Denmark, Danish town and seaport on the east coast of the Jutland peninsula. Tourism, education and commerce are important sectors in the economy of Grenaa. It is the only larger town on Djursland. Grenaa is the municipal ...

by the

Kattegat The Kattegat (; ; ) is a sea area bounded by the peninsula of Jutland in the west, the Danish straits islands of Denmark and the Baltic Sea to the south and the Swedish provinces of Bohuslän, Västergötland, Halland and Scania in Swede ...

sea to the railway town of

Kolind Kolind is a railway town, with a population of 1,924 (as of 1 January 2024), rak.dk/ref> The former lake was drained through a series of canals, dams, and pumping stations beginning in May 1874. osters at Fannerup Pumping Station/ref> Today, the area is rich farmland kept dry by means of electric pumping stations.

Geography

The sound was formed by a low

glacial valley U-shaped valleys, also called trough valleys or glacial troughs, are formed by the process of glaciation. They are characteristic of mountain glaciation in particular. They have a characteristic U shape in cross-section, with steep, straight s ...

system and is surrounded by cliffs up to 35 meters high. During the

Stone Age The Stone Age was a broad prehistory, prehistoric period during which Rock (geology), stone was widely used to make stone tools with an edge, a point, or a percussion surface. The period lasted for roughly 3.4 million years and ended b ...

, Kolindsund was a saltwater

sound In physics, sound is a vibration that propagates as an acoustic wave through a transmission medium such as a gas, liquid or solid. In human physiology and psychology, sound is the ''reception'' of such waves and their ''perception'' by the br ...

that separated the

peninsula from the mainland, creating an island. By the

Middle Ages In the history of Europe, the Middle Ages or medieval period lasted approximately from the 5th to the late 15th centuries, similarly to the post-classical period of global history. It began with the fall of the Western Roman Empire and ...

, the entrance of the sound had been blocked off near the town of

Grenaa Grenaa (or Grenå) is a Danish town and seaport on the east coast of the Jutland peninsula. Tourism, education and commerce are important sectors in the economy of Grenaa. It is the only larger town on Djursland. Grenaa is the municipal seat, a ...

, turning the area into a navigable lake, which likely only had a depth of a few meters. This closure was likely caused by wind-driven sand drifts in combination with sea level changes and/or land elevation changes. Today, the bottom of the drained lake is on average below sea level. The width of Kolindsund varies between and . Throughout all of the sound there is a system of drainage pipes which divert water towards the middle canals and then into pumping stations. The fertile clay-like soil in the sound consists mainly of two types of aquatic deposits, marine and freshwater

silt Silt is granular material of a size between sand and clay and composed mostly of broken grains of quartz. Silt may occur as a soil (often mixed with sand or clay) or as sediment mixed in suspension (chemistry), suspension with water. Silt usually ...

. The marine soil originates from salt water deposits, has a low carbon content, and is up to 40% clay. The freshwater silt has a carbon content up to 5%. These silt and clay deposits were combined with peat-matter to form

gyttja Gyttja (sometimes gytta, from Swedish ) is a mud formed from the partial decay of peat. It is black and has a gel-like consistency. Aerobic digestion of the peat by bacteria forms humic acid and reduces the peat in the first oxygenated metre (gen ...

. Today, there is concern that possible future

rising sea levels The sea level has been rising from the end of the last ice age, which was around 20,000 years ago. Between 1901 and 2018, the average sea level rose by , with an increase of per year since the 1970s. This was faster than the sea level had e ...

due to climate change might make it more difficult to keep the former lake dry as farmland. In the past few decades, the region has seen an increase in flooding, which has led to frequent crop loss in the neighboring areas not protected by the Kolindsund's pumping system. The sound itself requires increasingly drastic improvements to prevent it from reverting into a lake, as the drying out of the areas soils has caused the surface level to sink further below sea level, which may eventually make the project unviable. There is ongoing discussion about restoring the area to its natural state.

History

Between 1872 and 1880, a project was carried out to drain the lake, converting the area into farmland. A shareholder company, ''Aktieselskabet Kolindsund'', oversaw the lake drainage project and the cultivation the former lake bed during the 19th century, having financed a number of drainage canals along with two pumping stations in order to drain the lake. Canals were dug on the north and south sides of the sound, with a third main channel dug through the center of the old lakebed. These drainage canals were excavated by hand, with picks, shovels, and wheelbarrows. Two pumping stations were initially constructed, both powered by steam engines and windmills until the 1930s. When the pumps started draining the lake in May 1874, the water level reportedly sank per day, eventually creating 2,800 ha of new farmland. Initially, the shareholder company which oversaw the project had only planned to drain the western part of the lake, and had attempted to construct a dam near the village of Fannerup in order to separate the lake into two sections. It is said that the dam they constructed simply sank into the mud. As a result, the projected eventually drained the entire lake instead. After the lake had been drained, farming of the lakebed begin in the 1880s and 1890s. In the first decades after the lake was drained, the farmland was not particularly profitable and the shareholders which had invested in the project saw limited returns. It was not until 1912 that the project made a profitable margin. In 1921, the land and all of its infrastructure were sold off by the shareholder company to private owners.

Pumping

During project planning prior to drainage of the lake in the 1870s, the amount of water that had to be pumped out to keep the lake dry was erroneously calculated to be less than half the actual pumping needed. The figure was based on the calculated influx from rainfall over the given area. In reality groundwater from the surrounding hills has a tendency to run under the cut-off canals and into the former lake, often surfacing as wellsprings that formed bogs, causing problems for farming. This extra amount of water meant that the pumping capacity was insufficient in the first decades after drainage of the lake. As a result, large parts of the sound were marshy fields that were too wet for plowing and growing of more intensive grain-based crops, and only suitable for grazing in summer. By the late 1920s, the pumping infrastructure was in need of repair, and an agricultural-economic crisis jeopardized the viability of the project continuing. On 2 May 1932, the

Danish Parliament The Folketing ( , ), also known as the Parliament of Denmark or the Danish Parliament in English, is the unicameral national legislature (parliament) of the Kingdom of Denmark — Denmark proper together with the Faroe Islands and Greenland. E ...

intervened, passing Law No. 139 which issuing loans and aimed to maintain the Kolindsund as farmland. The legislation also officially recognized the rights of the unionized workers who were involved in the labor-

intensive farming Intensive agriculture, also known as intensive farming (as opposed to extensive farming), conventional, or industrial agriculture, is a type of agriculture, both of arable farming, crop plants and of Animal husbandry, animals, with higher levels ...

of the sound. The ''Pumpelaget Kolindsund'', a landowners' association which still exists, officially designated to oversee the pump and canal infrastructure. Between 1935 and 1938, the ageing wind and steam pumps were replaced by two electrically driven pumping stations which are still in use today. At the same time, the canals' dams were reenforced. The renovations of the 1930s increased the efficiency of the pumping infrastructure. The water table of the area was lowered, turning even the marshy areas of the sound into high-yield and stable farmland, which is still the case today. Today, the two 240-horsepower pumps located in the villages of Fannerup and Enslev are turned on as needed, regulated by the water level in the canals that feed water to the pumps. The Fannerup station drains the western end of the sound, while the Enslev station drains the east; both stations pump the excess water into the northern canal, from which it runs into the

near

. A third pumping station was constructed more recently which drains the middle of the sound and pumps the excess water into the southern canal.

Farming

Farming in Kolindsund does not require expensive and energy consuming irrigation even in the driest of summers, which is otherwise widespread in Denmark. However, the energy must be expended to keep the drainage pumps running year round in the sound. The high yields of Kolindsund are in part based on the nutrient-rich silt-based soil, deposited through millennia at the bottom of the former lake and sound in layers that are up to 20 meters thick. The soil is free of stones and rocks. In some places the fields are colored with white streaks of prehistoric banks of oyster and mussel shell that have been ploughed up, giving witness to the marine past of Kolindsund. A similar type of drained sound and lake farmland in Denmark with mussel-rich soil can be seen in the

Lammefjord The Lammefjord is a polder in Denmark at the base of the Odsherred peninsula. Previously a deeply branched arm of the sea leading west from the Isefjord, most of it is now Land reclamation, reclaimed as agricultural land. The eastern third, outside ...

located on the northern part of Denmark's largest island,

Zealand Zealand ( ) is the largest and most populous islands of Denmark, island in Denmark proper (thus excluding Greenland and Disko Island, which are larger in size) at 7,031 km2 (2715 sq. mi.). Zealand had a population of 2,319,705 on 1 Januar ...

. Lammefjorden was also pumped dry in the 1870s. Here vegetables, not least carrots, are established crops. This is not the case in Kolindsund, even though the potential might be there due to the same types of soil. Grains, cereals, and rapeseed are among the most commonly cultivated crops in the sound, though smaller quantities of spinach, beets, poppy seeds, and caraways seeds are also grown. The region typically produces more than 100 hkg/ha of wheat.

Gallery

File:Kolindsund, pumpestationen i Fannerup.JPG, The pumping station in Fannerup, built in the 1930s. File:Det centrale Kolindsund.JPG, The central part of Kolindsund lies about below sea level on average, and is fertile farmland. File:Kolindsund Nordre landkanal.JPG, The North Canal down from Skiffard. Together with the South Canal the two canals cut of the streams that would otherwise fill Kolindsund with water. A third canal, the Middle Canal, connects to two pumping stations to the North Canal.

References

Literature

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External links

Video about Kolindsund
Kolindsund - Former Lake/A Drive/Djursland/Denmark
{{Authority control Lakes of Denmark Former lakes of Europe 1874 establishments in Denmark Agriculture in Denmark