Flood causes, types, and effects on human society

Floods are an overflow of water that submerges land and usually happen because of a large amount of rainfall, saturated soil, and/or the capacity of the body of water is exceeded:

Often floods are seasonal in nature, coming after Spring rains.

Floods also occur in rivers, when flow exceeds capacity in certain areas of the river channel.

Floods have impacted society for centuries because people like to live near water and water transportation.

In certain parts of the world, typically those with regular monsoon conditions, flooding is a regular seasonal issue

Suggested graphics: http://www.kidcyber.com.au/IMAGES/Floods4.jpg

Types of Floods -- The flood type depends on the geographic location of the body of water and its tendencies:

Areal flooding happens when flat, low-lying areas cannot absorb any more water

River floods occur when the river cannot carry away all the extra water and the river overflows

Coastal floods are usually caused by harsh weather blowing waves onto land.

Flash Flooding is a quick flood caused by a sudden cloudburst or thunder storm. Often these happen in mountainous areas with steep slopes.

Flooding from Human Action occurs when an artificial structure like a dam fails, or levees or pipes burst or are poorly constructed.

Suggested graphics: http://www.sciencemediacentre.co.nz/wp-content/upload/2011/02/flood.jpg

Flood Causation -- Flood can occur for a number of reasons, which makes them incredibly hard to predict and prepare for, particularly since humans tend to congregate around water.

Water from storms can no longer be absorbed into the soil; either pools or runs to lower elevation.

Heavy snowfall pack in areas followed by strong Spring/Summer rains

Intense precipitation -- thunderstorms, etc. Or release from a landslide or glacier

In estuaries caused by tidal surges from storm-force winds

Tsunami's or hurricanes -- storm surges

Catastrophic from dam breakage, earthquake or volcanic eruption -- also called outburst flooding

Suggested graphics: http://www.cnn.com/video/weather/2011/01/12/vo.sri.lanka.floods.slrc.640x360.jpg

Effects of Flooding, Part 1

Primary effects -- damage to structures, bridges, buildings, sewage system, roadways, canals

Floods have had a major impact on human society for centuries

Floods disrupt society completely; including social structures and economics

Transportation issues affect surrounding areas

People may need to be evacuated and rehoused for a time

Disruption in entire socio-culture template

Suggested graphics: http://news.xinhuanet.com/english/2008-06/15/xin_5020605152044156235937.jpg

Effects of Flooding, Part 2

Secondary effects -- as the water recedes or damage due to pressure, weather, etc.

Secondary effects may last for months, even years

Water supplies -- water may become contaminated

Potable water becomes rare

Spread of waterborne diseases (lack of sanitation, standing water)

Crops and food supplies ruined, sometimes entire harvests

Forest and land -- many trees die from suffocation

Transport links are down, hard to supply emergency aid

Suggested graphics: http://si.wsj.net/public/resources/images/WO-AH656_THAIFL_G_20111103200730.jpg

Effects of Flooding, Part 3

Long-term effects can devastate a region

Economic hardship due to decline in tourism, insurance and building costs, food shortages, price increases, lack of work, displacement of people

Psychological -- traumatic from death, injury, displacement, lack of support, loss of property, and complete life-change occur

Suggested graphics: http://1.bp.blogspot.com/_nMLR3Feb9RM/TUe8wRAOj0I/AAAAAAAAG7I/PkbF5ZVn9ow/s1600/pakistanfloodsAP

Floods caused by global warming

Some studies show that global warming and changes in weather patterns increase the likelihood of flooding

Increased precipitation in some areas can be one result of polar or glacier melts

Warm air holds more moisture, making outbreaks of heavier than usual rainfall more frequent, particularly in areas that are not flood prone

Some scholars think that the 2000 Floods in Britain were cause by climate change conditions.

Source: http://www.telegraph.co.uk/earth/earthnews/8328705/Floods-caused-by-climate-change.html

Suggested graphic - http://i.telegraph.co.uk/multimedia/archive/01827/Floods2_1827722b.jpg

Floods and Urban Planning

Increased urbanization, particularly in poor countries, without adequate building codes

Lack of storm drainage facilities or outmoded and poorly constructed facilities

Inadequate construction of levees, dykes, etc. (e.g. Katrina)

Inadequate disaster planning and evacuation procedures

Suggested graphic - http://cdn.punchng.com/wp-content/uploads/2012/06/Lagos-flood.jpg

Flood Control, Part 1

Humans have been trying to control floods for thousands of years. However, some flooding, particularly along the great river valleys (e.g. Nile) were the reason agricultural activities flourished and civilization developed

There is a balance between the regular flooding of river areas and catastrophic flooding

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Flood Control, Part 2

Dams and reservoirs are designed to aid in flood protection and control. They do this by controlling water levels and allowing water to flow as needed, but to protect lower elevations by storing water behind the dam wall.

River defenses -- Levees, bunds, reservoirs and weirs (low head dam) are all used to prevent rivers from bursting

Coastal defense -- sea walls, barrier islands, tide gates, enhancing beach areas

Suggested graphics: http://t1.gstatic.com/images?q=tbn:ANd9GcR8qfhdv0UvHzxKQsI8D1gJ06Ec72uZAtyhZzjc8VhjQb9k80MQ8z2n0mGv and/or http://crooksandliars.com/files/uploads/2008/06/illinois-levees.jpg

Flood Control, Part 3

Different regions have adapted flood control based on their economic wealth, type and frequency of flooding, and the density of population near flood-prone areas.

Americas -- Usually miles of levees, flood gates, and drainage systems

Asia -- Some building of massive dams, but deforestation contributes to more flooding

Future of Flood Control -- Part 1

It is important to remember that floods are unpredictable, and do not follow preset rules. In addition, as more and more people move into flood prone areas, aid, evacuation, and recovery become more problematical.

Use of technological models and tools like GIS planning, in which current and historical information can be modeled globally, will help identify high-need areas.

We need to learn to think about the earth in broader aspects, not just a town or a region, but how weather patterns are global in nature.

Suggested graphic:

http://www.physicalgeography.net/fundamentals/images/veg_map_small.gif

Future of Flood Control -- Part 2

Gaia concept -- Earth as an organism, forests are lungs, waterways are veins, develop a though-process to see the earth more in total, not in isolation

Balance human and environmental needs

Find ways to spend proactively instead of reactively -- e.g. millions are sent to flood disaster areas, but then no money to build infrastructures to prevent flooding

Use technology to aid in disaster education and prevention

Suggested graphic: http://1.bp.blogspot.com/-kjo5IFUGD5c/T-mywgxempI/AAAAAAAANmU/mU6s2fxSexw/s1600/Yup+its+still+there.jpg

SOURCES

"Dams and Levees." Infrastructure Institute. (2009). Web. Oct. 2012.

"Ice, Snow and Glaciers: The Water Cycle." United States Geological Society. (2012). Web. Oct. 2012. .

Agthe, D. "Integrating Market Solutions into Government Flood Control Policies." Water Resource Management 14.4 (2004): 1573-650. Print.

Brown, P. "Melting Ice Cap Triggering Earthquakes." The Guardian. 2007.

Fink, S. Crisis Management: Planning for the Inevitable. Lincoln: IUniverse, 2002. Print.

McCully, P. "On Water - Dams and Levees heighten Flood Danger in a Warming World." The San Francisco Chronicle. (July 29, 2007). Web.

McCully, P. "Before the Deluge: Coping with Floods in a Changing Climate," IRN Dams,

Rivers, and People Report 2007. International Rivers Network. 2007. Web.

McKusky, T. Floods. New York: Facts on File, 2009. Print.

Ruben, C., ed. Emergency Management: The American Experience, 1900-2005. New York: Public Entry Risk Services, 2007. Print.

Sparks, R.E. The Great Flood of 1993. Boulder, CO: Westview Press, 1996. Print.

Sylves, R. Diaster Policy and Politics: Emergency Management and Homeland Security. New York: CQ Press. 2008. Print.

May need to break into two slides

May need to break into two slides