Characteristics of River Flooding
When it rains, some of the water is evaporated back into the atmosphere, but some will also drip from vegetation onto the soil creating small pools known as surface storage. Some of the water in the surface storage will absorb into the ground in the process of infiltration. If the water isn’t able to infiltrate into the soil due to impermeable or saturated soil, water will flow sideway on the surface which is referred to as surface runoff. They will then reach the river or lake. The water stored in the rivers may runoff to the sea.
River flooding occurs when water can’t no longer be stored or removed from the river because of too much water therefore water will overflow and submerges land. There are many reasons that can cause the amount of water in rivers to increase, which includes both natural and human causes. The natural causes include large amount of rainfall and snowmelt due to global warming. The major human cause of flooding is deforestation. Large areas of forests near the rivers are destroyed therefore there is no trees to soak up the water causing more water to runs off to the rivers.
[Source of picture: http://hk.geocities.com/ka_kit_one/causes2.htm]
River flooding can cause primary effects, secondary effects as well as long-term effects.
The primary effects include both physical damage and casualties. The physical damage includes buildings, houses, and everything along the direction of the flood is destroyed. River flooding also causes the loss of lives. The secondary effects of flooding include water supplies- there won’t be safe drinking water. Flooding can also lead to diseases such as dysentery and diarrhea. Another secondary effect of river flooding is food shortages. Due to flooding, all the crops will be destroyed. Flooding can also affect the economics of a country. There will be a temporary decline in tourism, extreme rebuilding costs, and food shortages can also lead to increase in food prize.
Flood doesn’t only damage the lives of humans and the man-made things, but flooding can also damage the nature. Flooding can cause soil erosion as well as destroy the wildlife habitat.
Areas affected by flooding
[Source for picture: http://www.water.gov.au/SiteImages/good_438up.jpg]
Effects of river flooding on LEDC’s and MEDC’s
- Due to a limited amount of money, there are limited available capital and technology in LEDC’s.
- There is also very little or no warning systems in LEDC’s therefore people won’t be able to escape from the flood.
- Due to bad health care, people in LEDC experiences more diseases after the flood. There are more rescue teams in MEDC’s than in LEDC’s.
- Poor quality housing in LEDC’s can’t withstand the water therefore they will all be destroyed while houses in MEDC’s are much stronger.
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[Sources for pictures: http://www.everythingexmoor.org.uk/images/lynmouthflood6.jpg and http://www.riverside.com/projects/marketing_flyers/pix%5Cbangladesh_ofda_8(1).jpg]
Why do people live in areas where flood can occur?
Even though people know that flooding can damage them, but many of them still live in areas where they could experience flooding. There are many reasons that make people wanting to live in areas where flooding can occur. Areas near the river are areas where flooding usually occur, but people still live near the river. Rivers provide many things to people such as food and water. Most of the people in Egypt live along the Nile River because they have to rely on the river for their daily life. They use water for fishing, growing crops as well as for communication. People in Egypt take flooding as the advantage because flooding can also help make the soil more fertile allowing crops to grow.
[Source for picture: http://www.civilization.ca/civil/egypt/images/geog04b.jpg]
Case Study: 1997 Grand Forks Flood
Date: April, 1997
Place: Grand Forks- a city that is located on the Red River, which is the border between North Dakota and Minnesota.
* The picture above is the map of the Red River before the flood *
[Source for picture: http://www.math.montana.edu/~nmp/materials/ess/hydrosphere/expert/rrf/red_river_flood/march30.jpg]
Causes:
The main cause of the Grand Forks flood is the weather conditions. The worst weather conditions in Grand Forks started from 1996-1997, where they receive 98.6 inches of snow. There are also 8 blizzards that hit Grand Forks.
The Eight Blizzards*
| Name of the blizzard | Period of time | Snowfall | Accumulated |
| Andy | Nov. 16-17 | 12 in. | 13.6 in. |
| Betty | Dec. 16-17 | 8.7 in. | 38.2 in. |
| Christopher | Dec. 20 | 4.2 in. | 42.4 in. |
| Doris | Jan. 9-11 | 8.8 in. | 56.5 in. |
| Elmo | Jan. 14-16 | 0.4 in. | 57.1 in. |
| Franzi | Jan. 22-23 | 8.6 in. | 67.4 in. |
| Gust | March 4 | 0.2 in. | 83.3 in. |
| Hannah | April 4-6 | 6.3 in. | 97.4 in. |
| | Total: 98.6 in. | ||
The last blizzard, Hannah was the biggest of all. It first begins with rain, which later freezes, Hannah lead to the enormous flood as the large amount of snow began to melt since March 21. As snow continued to melt, the amount of water in the Red River was climbing out of its banks and finally flooding occur in Grand Forks in April 18th, 1997.
* This picture shows the map of the Red River during the flood *[Source for picture: http://www.math.montana.edu/~nmp/materials/ess/hydrosphere/expert/rrf/red_river_flood/rvapril21.jpg]
- 300 homes are covered with water to their rooftops
- Dikes failed and water surges across the Red River Valley
- 8,700 residents were evacuated out of East Grand Forks and 52,000 residents were evacuated from Grand Forks.
- Electrical problem in the Security building caused a sparked fire, but trucks couldn’t get through the extremely high water therefore 11 buildings were damaged.
People who live along the Red River were able to prepare for the flood, but the amount of water were what they didn’t expect to happen. According to the National Weather Service, they predicted that the flood would be as high as 49 foot, but it turned out to be at 54 feet. People in Grand Forks had out in a lot of effort into dumping sand into the river as well as building sandbag dikes to prevent them from the flood. People also used sandbags and clay to strengthen dikes throughout the city. They built dikes that were 52 feet high, which they thought they were ready to handle the flood.
[Source for picture: http://www.geo.mtu.edu/department/classes/ge404/mlbroder/mitigate.html]
Conclusion
Another major world problem we are facing is global warming which is related to flooding. Global warming causes the temperature of the earth to increase due to the large amount of carbon dioxide that is released into the atmosphere. Global warming causes the ice from the north and south poles to melt, which will increase the amount of sea level. As time pass by, the climate is beginning to change from cold to hot and more ice will be melted, which might lead to a big flood where the whole world will be under water.
Work Cited (information):
http://www.fenhydro.co.uk/Flooding_rivers.htm
http://en.wikipedia.org/wiki/Red_River_Flood,_1997
http://en.wikipedia.org/wiki/Flood
http://geobytesgcse.blogspot.com/2006/12/differences-in-flood-management-between.html
http://hk.geocities.com/ka_kit_one/causes2.htm
http://www.geo.mtu.edu/department/classes/ge404/mlbroder/during.html
http://www.geo.mtu.edu/department/classes/ge404/mlbroder/mitigate.html
http://www.geo.mtu.edu/department/classes/ge404/mlbroder/contrib.html
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