Chapter 6 paragraph 3 rising sea levels & protection

• Aardrijkskunde
• Middelbare school
• mavo, havo
• Leerjaar 2

At the end of this lesson

why the sealevel is rising and how we protect the coast in the Netherlands

Rising sea levels

Melting land ice + expanding sea water

Why does melting sea ice not make a difference?

Relative sea level rise

subsidence + sea level rise

Subsidence makes the land lower in relation to the sea level

Subsidence cause 1

During the ice age Scandinavia sank about 250 meters

--> cause: a kilometers thick layer of land ice

--> the ground in Scandinavia is now rising back up

--> the Netherlands is sinking from a 'see-saw' effect 

Subsidence cause 2

Low-lying areas of the Netherlands: subsidence from dewatering: without dewatering the soil is too wet for agriculture

Especially in peatlands: 

- peat = soggy, spongy soil typ

 - composed from dead plant matter

- when you remove water: soil collapses 

- part of peat above water surface: exposed to oxygen: decomposition: soil sinks more

Subsidence cause 3

Groningen: subsidence because of mineral extraction --> natural gas

Sand as protection

• Measures to protect the coast:
• Dike improvement
• Dune improvement with sand 

Sand suppletion: adding sand. Why? 1. The waves lose their destructive force, 2. Dunes become higher and wider because the wind blows the sand onto the dunes.  

To work

• Read paragraph 6.3 
• Make assignments 5, 6 and 7
• 8 minutes silence, after that you can discuss with your neighbour. 

Which three things cause subsidence in the Netherlands?