Flood Prediction & Mitigation (SL IB Geography)

• It can be difficult to predict floods
• Flood prediction requires different types of data, including:
  • Real-time rainfall levels
  • Knowledge about the type of storm producing moisture
  • Knowledge about the characteristics of the river’s drainage basin
• Weather satellites and radars are used to predict river flooding
• They help to identify the areas most vulnerable to flooding

Flood prediction in Bangladesh 

Flood prediction in Bangladesh

• Warnings can be given through social media about potential flooding
• Flooding is becoming more frequent as a result of climate change

Improving flood prediction

• Improved flood prediction can be achieved by:
• Mapping of channels
• More detailed collection of meteorological information
• More sharing of information about the risk of flooding between countries who share international drainage basins

• The two main categories of flood management are hard and soft engineering:
  • Hard engineering involves building structures or changing the river channel
  • Soft engineering works with natural processes of the river and surrounding environment
  • Soft engineering is increasingly popular
  • Soft engineering is an example of mitigation where schemes aim to minimise damage rather than trying to prevent flooding

Type of Engineering	Advantages	Disadvantages
Dams	Hold back water during times of flood Release water when flood risk is reduced	Increase in loss of water due to evaporation Channel erosion Possible spread of diseases such as malaria
Afforestation	Could increase interception and reduce overland flow Could possibly soak up excess rainwater	Young trees cannot absorb or intercept as much as more mature trees  Most trees lose their leaves in the winter and so interception reduction is decreased
Channel modification	Can be done via straightening and enlargement Enlarging the cross-sectional area increases the bankfull discharge and hydraulic radius Velocity can increase if meanders are removed	Expensive May have to remove buildings to complete channel modification
Levee strengthening	Can protect buildings in the surrounding areas from flooding  Barriers are less expensive than channel modification Can be used to divert water to less valuable land

Planning

• Personal insurance may not always be available for lower-income countries
• Sand bags
• Sealing doors and windows
• Placing electrical generators higher up in the building
• Building houses on stilts
• Flood insurance, if available
• Government officials can use disaster aid