3.3 Sometimes too much

• Aardrijkskunde
• Middelbare school
• vmbo t, mavo, havo, vwo
• Leerjaar 2

3.3 Sometimes too much

Part 1

Learning outcomes 3.3

- You know which areas have greater flood risks.

- You understand why floods have major consequences for the inhabitants of those areas.

- You can name a number of measures that reduce flood risks.

Flood risk areas

Areas that are at high risk of flooding

1. River and coastal plains.

2. Areas at the foot of a mountain range with rocky surface (peak discharge).

Peak charge

Piekafvoer

If the water level rises sharply in a short period of time, this is called a peak discharge.

Peak discharge

Flooding

In the Yangtze, rain and melt water in spring and summer cause a high peak discharge (=Extremely high water discharge in a river). People make the problem worse through deforestation (=Cutting down forests).                                   

 

       Better absorption of water by vegetation = lower peak discharge.

Less vegetation = higher peak discharge                               

3. Areas where snowmelt coincides with heavy rainfall in summer.

4. Areas where hurricanes occur.

5. Areas where deforestation is taking place upstream.

6. Areas which have a lot of urban development. (petrification, urbanization)

7. Areas with soil subsidence due to the pumping of groundwater.

Soil subsidence

• Pumping up of groundwater 
• Soil subsidence: the soil will sink

Help! 

I can't

 reach

Bodemdaling

• Ice age: seesaw
• Groundwater, peat
• Extraction of minerals

Homework

Find a specific place where this takes place in each of the 7 areas.

3.3 Sometimes too much

Part 2

Make groups existing of 3-4 students

The number of floods is increasing

How is it possible that the number of floods is increasing?

Warming of the atmosphere -> warming of the oceans -> warm sea water -> more water vapor (especially in warm air) -> more heavy storms and heavy precipitation

River deltas: extreme storms with heavy precipitation, sea level rise due to expanding seawater, melting polar caps, glaciers and subsidence due to drinking water extraction

Consequences and measures

What could be the consequences of a flood?

What can be a measure in the short term and in the long term?

Short term

- Construction of dikes, dams and buffer basins.

- Monitor the weather throughout the watershed.

- Inform and train citizens (evacuation exercises).

- Securing drinking water and food after possible flooding.

Long term

- Make room for the river (provide flood plains).

- Reduce the enhanced greenhouse effect.

- Create a location policy in which people are excluded or moved from risk areas as much as possible.