Chong Boon Secondary SchoolHumanities Department

Geography UnitSec 2 Geography

Unit 5 Lesson 4

“How should cities prepare for floods?

Thinking QuestionWhat has

Singapore done to mitigate the

impact of floods?

The Cost Benefit Analysis

• For every choice, there are 2 key factors involved.

• The costs (tangible cost and opportunity cost)

• The benefit (tangible and intangible)

Mitigation measures in Singapore

• Regulation– Zoning

– Elevated properties

• Investment in infrastructure– Levees and floodwalls

– Channel improvement

• Disaster preparedness– Forecasting and warning system

– Evacuation drills

Regulation

Refers to rule of law which is enforced by an authority.

States how something should be done.

Zoning & Development control requirements

Zoning regulations in Bangkok

Zoning

Plans for the physical development of the land and its uses.

Specifies residential, industrial, commercial, recreational areas.

Flood-prone areas are zoned as low-value developments.

Low investments involved, less loss in floods.

Elevated Properties

Elevated Properties

Raising the properties to a certain height.

Imposing of the minimum platform level (MPL)

Requires buildings to be built above the potential flood level.

Commonly, steps / slopes are built to ensure buildings meet the MPL.

Infrastructure investment

Investment in Infrastructure

Investing in infrastructures like levees, floodwalls and channels

reduce flood impact.Current infrastructure needs to

be maintained to ensure serviceability.

Levees and floodwalls

Levees and floodwalls

Barriers against floods and floodwater.Levees – raised river banks (natural / manmade) used to keep river floods

from the banks.

Floodwalls – man-made concrete structures. Also to keep flood water

away.

Channel Improvement

Channel Improvement

Changes made to the river channel or canal

Increasing capacity to hold water / discharge water

quicklyPrevents overflowing.

Disaster Preparedness

Disaster Preparedness

Cities take pre-emptive steps to reduce damage.

Advance flood warning also helps reduce flood impact.

Emergency drills and training also helps mitigate impact.

Forecasting and Monitoring

Forecasting and warning system

Systems that provide forecasting of weather conditions that would lead to

flooding.Monitoring systems that warn when the drainage systems are approaching flood

levels.Provides reaction time for residents in

affected areas.Opportunity for the residents to take action

(move / evacuate / put up flood barriers)

Evacuation Drills

Evacuation Drills

Critical for cities with large populations.

Plan to evacuate the large number of people in the shortest time.

Drills reduce panic and improve efficiency.

Ensures spread of essential skills and services (first aid stations)

Summary

What are the ways in which regulation, infrastructure and

disaster preparedness can be used to prepare

cities for floods?

Team Task

• In your groups, apply Cost Benefit Analysis to the measures that you have been allocated.

• You have 15 minutes

• Pick the best and write a short speech (1 minute) to explain how it is the most ideal measure. Your team must have a presenter for this.

What are the benefits and challenges of zoning as a flood mitigation

measure?

Benefits Challenges

What are the benefits and challenges of minimum platform level as a flood

mitigation measure?

Benefits Challenges

What are the benefits and challenges of levees & floodwalls as a flood

mitigation measure?

Benefits Challenges

What are the benefits and challenges of channel improvement as a flood

mitigation measure?

Benefits Challenges

What are the benefits and challenges of forecasting and warning system as a

flood mitigation measure?

Benefits Challenges

What are the benefits and challenges of evacuation drills as a flood

mitigation measure?

Benefits Challenges