FloodsFloods

Week 4Week 4

Questions forHomework & Discussion

Questions forHomework & Discussion Would you live in a flood-prone

area?) What level of risk from flooding

is acceptable to you? How would you know if the

flood risk was assessed accurately?

What should be done to prepare for the hazard and prevent catastrophe?

Would you live in a flood-prone area?)

What level of risk from flooding is acceptable to you?

How would you know if the flood risk was assessed accurately?

What should be done to prepare for the hazard and prevent catastrophe?

Questions to considerQuestions to consider

What causes the flood hazard to vary? What is the impact of climate change on

the flood hazard? The five concepts from Chapter 1

What causes the flood hazard to vary? What is the impact of climate change on

the flood hazard? The five concepts from Chapter 1

What are the types of flooding? What are the types of flooding?

Causes of FloodingCauses of Flooding

Heavy rainfall

rate of rainfall exceeds infiltration capacity of soil

Heavy rainfall

rate of rainfall exceeds infiltration capacity of soil

Drainage Basin

Drainage Basin

area contributing to river

drainage density

soil permeability

relief

area contributing to river

drainage density

soil permeability

relief

Floodplain

Floodplain

flat area next to a river

area subject to flooding

stores flood water

flat area next to a river

area subject to flooding

stores flood water

HazardsHazards

Flooding Sedimentation Erosion

Flooding Sedimentation Erosion

Transportation disruption

Disease Displacement Agricultural

losses

Transportation disruption

Disease Displacement Agricultural

losses

Risk ZonesRisk ZonesFlooding: 1993-1997

Presidential disaster declarations related to

flooding 1965-2003

•Green: one declaration•Yellow: two declarations

•Orange: three declarations•Red: four or more

Forecasting FloodsForecasting Floods

Predicting FloodsPredicting FloodsMeasure rainfallModel runoff response

Measure rainfallModel runoff response

drainage basin characteristics

channel characteristics

past events

drainage basin characteristics

channel characteristics

past events

Response to Flood HazardResponse to Flood Hazard

Flood control dams retention ponds levees channelization

Flood control dams retention ponds levees channelization

Response to Flood HazardResponse to Flood Hazard Insurance: only

through federal government

Zoning

Insurance: only through federal government

Zoning

Human ImpactHuman Impact Increases runoff

pavement buildings drainage

improvements

Increases stage levees bridges channel alteration

Increases runoff pavement buildings drainage

improvements

Increases stage levees bridges channel alteration