Social Issue Concerning the Environment:
Flash Flood Caused by Clogging
By: Shaina Mavreen D. Villaroza
What are flash floods? Flash flood is a sudden and often destructive
surge of water down a narrow channel or sloping ground, usually caused by
heavy rainfall (Encarta Dictionaries). Flash floods occur within a few minutes
or hours of excessive rainfall, a dam or levee failure, or a sudden release of
water held by an ice jam. Flash floods can strike any time with little or no
warning. City streets can become rivers in seconds. You will not always
have a warning that these deadly, sudden floods are coming.
Most flash flooding is caused by slow-moving thunderstorms,
thunderstorms repeatedly moving over the same area, or heavy rains from
hurricanes and tropical storms. Blocked catch basins, storm drains, water
main breaks, and sewer lines can also lead to flooding (Flooding, 2009).
There are other types of flooding aside from flash flooding such as
river flooding, coastal flooding, and urban flooding (Flooding, 2009).
Flooding along rivers is a natural and inevitable part of life. Some floods
occur seasonally when winter or spring rains, coupled with melting snow, fill
river basins with too much water too quickly. Torrential rains from decaying
hurricanes or tropical systems can also produce river flooding. Winds
generated from tropical storms and hurricanes or intense offshore low
pressure systems can drive ocean water inland and cause significant
flooding. Escape routes can be blocked off and blocked by high water.
Coastal flooding can also be produced by sea waves called tsunamis,
sometimes referred to as tidal waves. These waves are produced by
earthquakes or volcanic activity. As land is converted from fields or
woodlands to roads or parking lots, it loses its ability to absorb rainfall.
Urbanization increases runoff 2 to 6 times over what would occur on natural
terrain (Fairbridge, R.W., 2008).
Several factors contribute to flash flooding. The two key elements are
rainfall intensity and duration. Intensity is the rate of rainfall, and duration is
how long the rain lasts. Topography, soil conditions, and ground cover also
play an important role (Fairbridge, R.W., 2008).
EFFECTS of Flash Floods to the Environment
Floods not only damage property and endanger the lives of humans
and animals, but have other effects as well. Rapid runoff causes soil erosion
as well as sediment deposition problems downstream. Spawning grounds for
fish and other wildlife habitat are often destroyed. High-velocity currents
increase flood damage; prolonged high floods delay traffic and interfere with
drainage and economic use of lands. Bridge abutments, bank lines, sewer
outfalls, and other structures within floodways are damaged, and navigation
and hydroelectric power are often impaired. Financial losses due to floods
are commonly millions of dollars each year (Flood Control Microsoft Encarta,
Flash flooding is the number one cause of deaths associated with
thunderstorms, claiming more than 140 lives each year (Flash Floods,
Properties and Flooding: Melbourne Water, 2008). Flash floods can roll
boulders, tear out trees, destroy buildings and bridges, and scour out new
channels. Rapidly rising water can reach heights of 30 feet or more.
Furthermore, flash flood-producing rains can also trigger catastrophic mud
slides. Most flood deaths are due to flash floods.
During periods of urban flooding, streets can become swift moving
rivers, while basements can become death traps as they fill with water.
Significant street flooding can pose risks to both pedestrians and drivers.
Floodwater from Sewage Back-ups or SBUs can pose serious health risks.
Sewage contains germs that may cause stomach or intestinal infections if
swallowed. It also may infect a cut on the skin or other open areas, such as
the eyes (NYC Hazards: Flash Flooding, 2009).
Nearly half of all flood related deaths occur in vehicles. Most of these
deaths take place when people drive into flooded highway dips of low
drainage areas. A low water crossing is where a road, without a bridge, dips
across a normally dry creek bed or drainage area. Motorists who attempt to
cross these flooded low water crossings are putting themselves, their
vehicles and any other occupants of their vehicles at deadly risk. Whatever
you do, don’t drive your car onto a flooded road, even if the water looks
shallow. Most flood accidents in the United States occur when vehicles drive
into floodwater (Williams, J., 2009).
RESOLUTION of the Issue
Keep your local drains clear of litter and debris to avoid blocked drains
that can cause floods. Even if the debris doesn’t block your own drains, it
could be swept downhill and cause flooding elsewhere. To prevent clogging,
throw your garbage properly and clean up drains (Flash Floods, Properties
and Flooding: Melbourne Water, 2008).
The basic methods of flood control have been practiced since ancient
times. These methods include reforestation and the construction of levees,
dams, reservoirs, and floodways (artificial channels that divert floodwater)
(Flood Control Microsoft Encarta, 2008).
Apply for a planning permit for any redevelopment or new building
works if your property has been defined as flood prone. In some cases,
changes may be required, such as raising floor levels, or reorienting new
building and driveways in a way that does not obstruct the flow of
stormwater. Avoid home improvement practices that exacerbate flood risks.
For example, consider grading paved areas such as paths and patios, as well
as other landscaping, so they direct flows around or away from your house
or garage (NYC Hazards: Flash Flooding, 2009).
National Weather Service announces ‘Flash Flood Watch’, which is
issued when it is possible that rains will cause flash flooding in a specific
area, and ‘Flash Flood Warning’, which is issued when flash flooding is
occurring or is about to occur in a specified area (Flooding, 2009).
Fairbridge, Rhodes W. "Geomorphology." Microsoft® Encarta® 2009 [DVD].
Redmond, WA: Microsoft Corporation, 2008.
“Flash Floods, Properties and Flooding: Melbourne Water”. 2008. Retrieved on
January 21,2013. http://www.melbournewater.com.au
"Flood Control." Microsoft® Encarta® 2009 [DVD]. Redmond, WA: Microsoft
“Flooding”.2009. Retrieved on January 22, 2013.
“NYC Hazards: Flash Flooding”. 2009. Retrieved on January 21,2013.
Williams, Jack. “A Guide To Storms”. Microsoft Encarta Premium 2009.