Coastal Europe
Climate Change Daily Repost

Coastal Europe fights climate change and it is a big dam problem

Many densely populated areas of Europe are precariously perched at, or even slightly below, sea level. Rising sea levels pose an existential threat to these low-lying coastal areas. Also, all indications are that the rate of sea-level rise is accelerating. However, abandoning cities to the oceans is an expensive proposition, and protection is deemed by many to be a better path into the future. Several proposals for massive dams, on a scale never attempted before, are under consideration as coastal Europe fights climate change.

The Northern European Enclosure Dam

Source: Northern European Enclosure Dam: more than 600 km longer than the Afsluitdijk, technically feasible, but mainly intended to show the scale of future interventions as climate change progresses. (C) NIOZ/ Sjoerd Groeskamp

Dutch scientists recently proposed damming off the entire North Sea and Baltic Sea to prevent rising sea levels from affecting Europe. Now that’s a very bold engineering idea.

The project requires a total of 635 kilometers (km) of construction split between two dams. The longest of these two stretches 474 km from the northern tip of Scotland to Bergen in Norway. The route forms the north barrier, and it also extends over 120 meters below sea level in some places. The southern dam stretches 161 km between South England and France.

This project far surpasses anything previously attempted.  Currently, the largest dam in the world is in South Korea. It extends 48 km in length and reaches water depths of slightly over 30 meters. The estimated sand needed for the concrete in these North Sea dams exceeds the entire annual sand budget of the world – 51 billion tons.

But there are other solutions for coastal Europe that forego the need for concrete and rely on traditional earthen embankments.

 The  Haakse Sea Dike

De Hacks Zeedijk Source: Innovation Origins (https://innovationorigins.com/rising-sea-levels-the-haakse-dike-an-escape-route-for-the-wealthy-west/

Another take on the problem focuses on a more direct coastal barrier.  The Haakse Sea Dike project envisions a coastal barrier stretching from Calais, France to Gothenburg, Sweden. Lying about 25 kilometers offshore and running for 1100 kilometers, the 3.5-kilometer wide dike completely separates coastal Europe from the rising seas. Current water depths along the path of the dike average 20 meters and the modeled structure rises an additional 20 meters above present sea level.

The dike consists of sand and silt dredged from the shoreward side of the feature. The final structure then provides a multi-purpose location for various other activities, including wind farms for generating electricity, airports located away from populated areas, recreational space, and freshwater storage lakes. 

Both the Haaske Sea Dike and the Northern European Enclosure Dam are ingenious ideas on a grand scale. They also both address future needs for coastal Europe. But, in both cases, their vision for the future leaves in its wake many unanswered questions.

Uncertainty

In the case of the Haaske Dike, uncertainty around the ability of an earth and sand structure to withstand the onslaught of ocean storm-waves points to the need for additional engineering on the seaward side of the dike.

Both projects irrevocably alter existing coastal and marine ecosystems. The interruption of tidal cycles would destroy the North Sea’s food chain. Salinity changes behind the dams or dikes threaten marine and estuarine environments, requiring large scale projects to reestablish freshwater ecosystems. Additionally, reduced circulation in the newly enclosed water bodies may create dead zones where hypoxic or anoxic environments develop. 

These projects are massively expensive and raise questions about whether now is the right starting time. If sea levels rise three meters this century and eight meters next century, then starting now focuses on problems two centuries ahead. However, this long-term focus acknowledges that either project requires multiple decades of construction time.

There are no easy answers, and rising seas present coastal Europe with a reality that requires solutions. Those solutions come in two varieties: Short term bandages on a decade by decade “as needed” basis or long-term solutions with a vision for the future.


ArcheanWeb:

Thinking big: Bold engineering ideas (Source: ArcheanWeb) – https://archeanweb.com/2020/02/27/thinking-big-bold-engineering-ideas/  Also:


Sources:

Scientist suggests damming the North Sea to protect Europe from climate change (Dezeen) – https://www.dezeen.com/2020/02/14/nothern-european-enclosure-dam-climate-change/ Also:

Rising sea levels: The Haakse Dike – an escape route for the wealthy west? (Source: Innovation Origins) – https://innovationorigins.com/rising-sea-levels-the-haakse-dike-an-escape-route-for-the-wealthy-west/  Also:

Do we need a second coastline? (By Jos Wassink; Delta) – https://www.delta.tudelft.nl/article/do-we-need-second-coastline Also:

Feature Image: Flooded Dike (Modified) By Apdency – Own work, Public Domain, https://commons.wikimedia.org/w/index.php?curid=10212666

William House
William is an earth scientist and writer with an interest in providing the science "backstory" for breaking environmental, earth science, and climate change news.