What are Floods?
Flooding is a natural disaster where a piece of land that is usually dry is submerged under water. Some
floods occur suddenly and recede quickly, while others can take days or months to build and regress.
When floods occur in an area where people live, the water can damage or even wipe away farms, houses,
bridges, cars, trees and other heavy items. Flood waters can be very dangerous. People even lose their
lives during floods.
Floods can happen due to a number of reasons: heavy rains, riverine flooding, flash flooding, dam failure
and a storm surge. Rainfall and run off are the major causes of floods. When rain falls over an area of land,
some is absorbed by the soil, while the rest becomes runoff and flows downhill. The area of land that
collects the runoff is called a catchment. Tides can add to the height of flood waters, increasing the area
flooded. Around the world, many people live on land that is subject to occasional flooding. These are
known as floodplains.
The size of a flood event is usually classified by its height (the level of water at a particular location in a
waterway). The Bureau of Meteorology uses three general categories of flooding related to water level:
major; which includes inundation of large areas, major disruptions, evacuations of houses and businesses,
moderate; which includes inundation of low-lying areas, removal of stock and evacuation of some houses
and minor; which includes inconveniences such as the closing of minor roads and the submergence of low
level bridges.
Flooding can be very dangerous. Only 15 cm (5 inches) of fast-flowing water is needed to knock you off
your feet. Floodwater can seriously disrupt public and personal transport by cutting off roads and railway
lines. Floods can distribute large amounts of water and suspended sediment over vast areas, redirecting
valuable soil nutrients to agricultural lands. However, soil can be eroded by large amounts of fast-flowing
water; ruining crops, destroying land and buildings and drowning farm animals.
Severe floods not only ruin homes, businesses and destroy personal property, but the water left behind
causes further damage to property and contents. Unfortunately, flooding not only disrupts many people’s
lives each year, but it frequently creates personal tragedies when people are swept away and drowned.
Page 1 of 3
Name: ______________________ Date: _________________
Comprehension Questions
1) What is flooding?
________
______ ____________
2) What damage can flooding do to a community?
________________________________________________________________________________
________________________________________________________________________________
________________________________________________________________________________
3) List some reasons why flooding can occur.
________________________________________________________________________________
________________________________________________________________________________
________________________________________________________________________________
4) How is the size of a flood measured?
5) What are the three categories used by the Bureau of Meteorology to describe a flood event?
6) Decide whether the following statements are true or false.
a) Only a small amount of fast-flowing water can knock you off your feet. True / False
b) Tides do not impact flood waters. True / False
c) Floods can occur suddenly, or take days and months to occur. True / False
d) A minor flooding event still requires evacuation of homes and businesses. True / False
e) Flood waters can be both good and bad for soil. True / False
Page 2 of 2
Name: ______________________ Date: _________________
Comprehension Answers
1) What is flooding?
Flooding is a natural disaster where a piece of land that is usually dry land, is submerged under
water.
2) What damage can flooding do to a community?
Farms, houses, bridges, cars, trees and many more heavy items. Some people even lose their
lives during floods.
3) List some reasons why flooding can occur.
Rains, riverine flooding, flash flooding, dam failure and a storm surge.
4) How is the size of a flood measured?
By its height – level of water at a particular location in a waterway.
5) What are the three categories used by the Bureau of Meteorology to describe a flood
event?
Major, moderate and minor.
6) Decide whether the following statements are true or false.
a) Only 15 cm of fast flowing water can knock you off your feet. True / False
b) Tides do not impact flood waters. True / False
c) Floods can occur suddenly or take days and months to occur. True / False
d) A minor flooding event still requires evacuation of homes and businesses. True / False
e) Flood waters can be both good and bad for soil. True / False
Page 1 of 1
