Causes and Effects of Flooding in Global and Thailand

Causes of flooding


It can be devided into 2 kinds. Natural and Manmade.


Natural Causes of Floods:


1.High rainfall




Heavy rainfall raises the water level. When the water level is higher than the river bank or the dams, the water comes out from the river,there will be flooding.


2.Snowmelt



Because of global warming, the temperature of this year is higher than the temperature of many years ago.The ice caps melt in spring, and the water goes into the sea. The water raises the sea level, and makes the river level rise. When river level rises, flooding may occur.


 3.Relief



Flooding often occurs in lowlands. This is because rivers flow more slowly in low-lying areas. If the water volume increases suddenly, floods occur.


 4.Coastal flooding
Flooding always occurs in coastal areas. High tides or storms cause the water level to rise. If the water level is higher than the level of the coastal lowland, flooding will occur.

 Human Causes of Floods
 1.Deforestation
Large areas of forests near the rivers have been cleared. The lands are used to make room for settlement, roads and farmland. Less vegetation protects the soil, the soil is quickly lost to rivers and the sea.This raises the river bed, so the river overflows its banks easily.




2.Poor farming
Some farming practices can damage the vegetation cover, so the soil will be washed into the river easily.
Overgrazing
People want more food and money. They graze too many animals on the land and the pasture is eaten away quickly. Less vegetation cover results in soil washed into the rivers easily.
Overcultivation
When a piece of land has been used for farming for a long period of time, the soil may became so infertile that no vegetation can grow on it. The land is less fertile than before so the soil washed into the rivers more easily


3.Poor water management



When the dams are poorly constructed or maintained ,they can easily collapse and this results in flooding. Moreover, poor plan of city construction can also cause flooding as the water can't flow out easily.
4.Population pressure


Because of large amounts of people, everything needs more, like wood, land and food……
Soil erosion happens more often and increases the risk of flooding.




Causes of flooding in Thailand


Main cause of flooding in Thailand is heave rain in monsoon season, overloaded capacity of dam, river. Geographical of Thailand, Northern Thailand is hill side, when there is heavy rain the water flow from northern river such as Ping, Wang, Yom, Nan to Chaopraya river, flood-plain area which is central area. When Kangsuaten dam and Naresuan dam are at full capacity, the water is released to central region to Pasakjolasit dam, if Pasakjolasit dam reach full capacity water will be released to lower region of Chaopraya river. Therefore flood happen.
Due to climate change, it become harder to predict the amount of water each year. There are about 6 main dams in central Thailand; only 3 of them were built to retain water. In 2010, first six month of the year Thailand face drought, so most of the dams retain water up to 90% capacity, when heavy rain occur dam capacity was full, flooding occur.

Pasakjolasit Dam

Naresuan Dam


Urbanization, the flood-plain areas that used to be the area to retain water were cover up to support unwell plan expansion of the city, block the natural drainage mechanism.


         Lack of cooperation between government’s organizations, some project may be an obstacle for other project. Government should issue clear regulation for usage of land in flooding area as a long-term prevention, not just some relief plans after floods occur.






Reference:
http://www.haii.or.th/wiki/index.php/ลุ่มน้ำในประเทศไทย
http://www.lks.ac.th/kukiat/student/betterroyal/social/20.html
http://kanchanapisek.or.th/kp5/suaten.htm
http://information.rid.go.th/news/a2.html




Effects of flooding


Thailand is under influence of monsoon, leads to heavy rain 1000-4000 cubic meter per year, 80% of rain is in rainy season (May - October) which flood likely to occur. Importantly, low land which is risky to flood are situated in the lower region of Chaopraya river include 9 provinces, 16.2 million residence, economic size is 44% of GDP. Thai people use 5% of water to consume, 5% for industry, and 90% for agricultural. In 2010 severe tropical storms, heavy rains and flash floods since mid-October have affected two-thirds of the country. The north-eastern provinces were the first to be hit, followed by the central and southern provinces. According to the government, the natural disaster has so far affected 13.4 million people in 51 of the country's 76 provinces, claimed at least 229 lives and forced the closure of some 3,441 schools.



Thailand is the home to 65 million people, the majority of whom live in rural, agricultural areas. The country is the world’s largest exporter of rice, and is often called “the rice bowl of Asia.” Agriculture employs 49% of the population and contributes 10% of GDP. The effects of climate change put Thailand’s rice crops at risk. One degree of warming will destroy the rice crops that are central to the economy.
Thailand is world’s largest rice exporter, with 7.5 million tons of grain shipped oversea in 2005. During the past decade, weather patterns in Thailand have fluctuated from severe droughts to severe floods, leaving residential and agricultural areas reeling. In 2010 were a series of flash floods that hit different areas in Thailand, 2,002,961 households, 7,038,248 people affected and agricultural area was damaged 7,784,368 Rai. Thai Farmers Association president, Prasit Bonchoey said on 11 Nov. “This year’s rice production is expected to drop by about 20 per cent due to the massive flooding in the country”. Environmentalists and scientists say that as the world gets hotter, floods, droughts and rising sea levels can push Thailand’s rice yield down significantly with huge impact on rural communities. Thai farmers are also fear of the changes they see in the weather even though they know little about global warming.

Not only agricultural sector, infrastructure sector was also get effected. After flooding the price of raw materials went up, some of the sites were in water so construction could not continue, and 30% of labors stop working and went back to their homeland to help their family. 126 roads in central area were damaged; 2134.70 million Baht will be given to repair the road.
For health impact, there were 107,000 patients caused by flooding. And not only disease which come with flooding such as Leptospirosis and diarrhea, but also mental health disease such as stress, anxiety, insomnia occur. Initial estimate spending in health care was 24.6 million Baht.

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