adults - floods - prevention

E-Learning Module for Adults

Floods

e-Learning for the Prevention, Preparedness and Response to Natural Disasters

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Part 1: Prevention

In part 1 of the Flood module , you will learn:

• WHAT IS A FLOOD? (causes and characteristics)

•THE TYPES OF FLOODS•WHERE DOES A FLOOD COME FROM AND WHERE CAN IT HIT?•WHAT TO BE AWARE OF IN THE AREAS? WHAT IS THE IMPACT?•WHEN DO YOU KNOW IF A FLOOD MIGHT HIT?

•WHAT ARE THE CONSEQUENCES OF A FLOOD?


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Part 1: Prevention

WHAT IS A FLOOD? (causes and characteristics)


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Part 1: PreventionFloods - What are they?

What is a flood?

To be able to prevent a flood, you must be able to identify the flood. The definition of a flood can be a variety of things and the same applies to the cause.

Image courtesy of nattavut at FreeDigitalPhotos.net


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What is a flood?

To be able to prevent a flood, you must be able to identify the flood. The definition of a flood can be a variety of things and the same applies to the cause.

The word "flood" covers a wide spectrum, as it can be everything from a flooded basement to a more permanent flood in connection with natural incidents, such as rise in the sea level, tectonic subsidence or manmade structures such as dam or dikes who breaks. Image courtesy of nattavut at FreeDigitalPhotos.net


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DefinitionsA flood is flooding of time limited character where normally dry areas are covered in water.


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A temporarily flood is caused by a time limited increase in water influx e.g. due to cloudburst, heavy and long lasting rain, melting snow who runs into a lake, stream or a fjord. Temporarily floods in lowland terrain also can be caused by one or more of combinations of flash flood incidents.


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A temporarily flood is caused by a time limited increase in water influx e.g. due to cloudburst, heavy and long lasting rain, melting snow who runs into a lake, stream or a fjord. Temporarily floods in lowland terrain also can be caused by one or more of combinations of flash flood incidents.

Flooding from waste water is dealt with by the municipality. Waste water covers all water including rain water derived from residential areas, commercial activity, buildings in general as well as forted areas.


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Part 1: Prevention Floods - What are they?

Flood categories

Flooding in Europe is divided into categories measured by following criteria:

Image courtesy of khuruzero at FreeDigitalPhotos.net


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Flood categories

Flooding in Europe is divided into categories measured by following criteria:•The source of the flood



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Flood categories

Flooding in Europe is divided into categories measured by following criteria:•The source of the flood•Geographical extent of the flooded area



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Flood categories

Flooding in Europe is divided into categories measured by following criteria:•The source of the flood•Geographical extent of the flooded area•Cause of the flood Image courtesy of khuruzero at

FreeDigitalPhotos.net


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Flood categories

Flooding in Europe is divided into categories measured by following criteria:•The source of the flood•Geographical extent of the flooded area•Cause of the flood•Speed of the flood



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1st criteria: The source of the flood

The source of the flood refers to where the water comes from. That means if the water comes from the sea (coastal flooding), from streams (stream flooding), from above (flooding due to rainwater) or from below (flooding due to ground water). The source of the flood is closely connected with the geographical extent of the flooded area.



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2nd criteria: The geographical extent of the flooded area

The geographical extent of the flooded area refers to:



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The geographical extent of the flooded area refers to:•Flooding in coastal zones and in river estuary, where the water enters in to low-lying coastal areas.



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The geographical extent of the flooded area refers to:•Flooding in coastal zones and in river estuary, where the water enters in to low-lying coastal areas.•Flooding of areas along creeks and rivers, where the creeks or rivers overflow their banks. Image courtesy of khuruzero at

FreeDigitalPhotos.net


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3rd criteria: Cause of the flood

The cause of the flood can be heavy precipitation, flash flood, earthquake (tsunami), hurricanes, etc. Common to them all is that they are made because of the weather. Flooding also can occur due to breach on manmade protection from flooding, such as dikes, or other barriers based on keeping water out of areas.



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4th criteria: Speed of the flood

The speed of the flood refers to the time perspective in connection with the occurrence of the flood and can be violent and sudden, e.g. during a precipitation incident or occurrence over time, where the water accumulates over days or weeks in catchment of big river basins.



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Part 1: Prevention

THE TYPES OF FLOODS


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Part 1: PreventionTypes of floods

Do you know the different types of floods?


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Part 1: Prevention Types of floods

1. Coastal Flooding

When land along the coast is flooded by the sea. Coastal flooding can include flooding caused by any of the following: storm surge, tsunami, sea level rise, coastal subsidence.


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2. Flash Floods

Sudden onset flooding that is usually associated with very intense localised rainfall. Peak discharges are only maintained for a matter of hours or even minutes.


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3. Fluvial Flooding (River)

Flooding that occurs when water volume and/or flow is too great to be contained within a river channel.


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4. Pluvial Flooding (Ponding)

Fluvial flooding is a type of flooding that can occur when relatively flat land, usually in more rural areas, becomes saturated. Direct rainfall rather than a river causes the flood, hence the name “pluvial”.


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5. Urban Flooding

Flooding caused by drainage problems within urban areas. This can include sewer flooding and back water caused by blockages in storm-water drainage systems.


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Part 1: Prevention

WHERE DOES A FLOOD COME FROM AND WHERE CAN IT HIT?


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Part 1: PreventionSources of a flood

Where does a flood come from?


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Where does a flood come from?Heavy

rain


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rain

Flash flood


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rain

Flash flood

Melting snow

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rain

Flash flood

Melting snow

Break on dikes

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Earthquake under water (tsunami)


rain

Flash flood

Melting snow

Break on dikes


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Where can it hit?

Example of high risk ares:


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Where can it hit?

•Coastal lines



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Where can it hit?

•Coastal lines•Streams and lakes



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Where can it hit?

•Coastal lines•Streams and lakes•Lowland and flat terrain (heavy rain)



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Where can it hit?

•Coastal lines•Streams and lakes•Lowland and flat terrain (heavy rain)•Upper catchment



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Where can it hit?

•Coastal lines•Streams and lakes•Lowland and flat terrain (heavy rain)•Upper catchment•Urban areas



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Part 1: Prevention

WHAT TO BE AWARE OF IN THE AREAS? WHAT IS THE IMPACT?


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Part 1: PreventionAwareness and impact

Flooding in lowland coastal areas can have severe consequences such as fatalities and economic damage. The probability of disasters from flooding in coastal areas is low and the flooding can be alerted one or more days in advance as this type of flood often will be a flash flood. However the flooding can hit a large geographical area, where a large amount of people live.

Floodings in lowland coastal areas


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Flooding from streams normally affects large areas of the lower catchment and can be foreseen several days before the incident occurs. The speed of the flooding will be low, but can nonetheless lead to severe damage.

Flooding of lower catchment areas



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Flooding in the upper catchment, urban areas, etc

Flooding in the upper catchment, urban areas, etc., normally occurs locally after heavy precipitation incidents. This type of flooding can spread out of a whole region, if the situation of the weather is characterized of a big low-pressure area. The flooding can have a severe effect in densely populated areas, which primarily covers material damages.


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Suddenly severe occurred flooding occurs, among others, in mountainous terrain and can occur very locally. This is the most common type of flooding in Europe. The consequences of this type of flooding is often catastrophic, because of the high speed of the flooding (flood surge), and the large amount of drifting goods. This can include a large number of fatalities and severe material damage.

Floodings in mountainous terrain



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Sudden flooding from cloudburst

Another, and more frequent, cause of suddenly severe occurred flooding is cloudburst which can occur within a short time and can hit very locally, with severe damages as a result.



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Part 1: Prevention

WHEN DO YOU KNOW IF A FLOOD MIGHT HIT?


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Part 1: PreventionWhen can there be a flood?

A flood might hit:

Strong winds

After or during a severe storm


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A flood might hit:

Strong windsHigh waterline coast by strong

wind



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A flood might hit:


wind

Shows high water level coast by storm



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A flood might hit:


wind

Shows high water level coast by storm After a storm



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A flood might hit:

Heavy rain Basement filled with water

If there is a heavy

rain coming


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Part 1: Prevention

WHAT ARE THE CONSEQUENCES OF A FLOOD?


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Part 1: PreventionThe signs of a flood

•You can have difficulties in moving around

The consequenses of a flood include the following:

Image courtesy of coward_lionat FreeDigitalPhotos.net


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•You can have difficulties in moving around•The water can be polluted and hide obstacles




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•You can have difficulties in moving around•The water can be polluted and hide obstacles•The flood can cause damage to the surroundings.o Nature – fallen trees




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•You can have difficulties in moving around•The water can be polluted and hide obstacles•The flood can cause damage to the surroundings.o Nature – fallen treeso Buildings – collapse




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•You can have difficulties in moving around•The water can be polluted and hide obstacles•The flood can cause damage to the surroundings.o Nature – fallen treeso Buildings – collapseo Landslide and mudslide




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•You can have difficulties in moving around•The water can be polluted and hide obstacles•The flood can cause damage to the surroundings.o Nature – fallen treeso Buildings – collapseo Landslide and mudslide

•You are in risk of getting too cold if the flooding is in the winter




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