Flood as a social problem There are few places on Earth where people need not be concerned about flooding. With the onset of rainy season, we need to be prepared for possible flash floods, landslides, and related disasters especially in high risk and vulnerable areas, that is why in Philippines flood is a major problem. Many people die every year because of this natural disaster. Most floods take hours or even days to develop, giving residents ample time to prepare or evacuate, but not in Philippines floods develop in a shorter period. Others generate quickly and with little warning. These flash floods can be extremely dangerous, instantly turning a babbling brook into a thundering wall of water and sweeping everything in its path downstream. There are many causes of flood. Typhoons may cause flooding to coastal areas. When there is a typhoon, the atmospheric pressure is low. Sea level rises and affects the volume of water flowing from the river to the sea. This indirectly leads to flooding. Flooding always occur in coastal areas. Because whenever there are high tides or storms, the sea level will raise. If the sea level is higher than the level of the coastal lowland, flooding will occur. Heavy rainfall raises the water level. When the water level is higher than the river banks or the dams, the water comes out from the river, there will have flooding. But even small amount of rainfalls in our country may cause flood.
This graph says that ten percent of the fatalities during natural calamities are caused by flood.
788,572 are the number of people who are affected by this phenomenon.
This tells that almost two million dollars cost of private and agricultural properties are damage and devastated
Most flood destruction is attributable to humans' desire to live near picturesque coastlines and in river valleys.
According to these statistics, flooding is a serious problem; it can lead to continuous rise of death rates, property damages, infrastructure devastations, health problems,

1. Economy
Economic loss
The flooding in Jiangxi of China in 1998 caused great damage. The economic loss was HK$156 billion, 400 buildings surrounding the lake were inundated, leaving more than 1 million people homeless.
Resources used in reconstruction
After flooding, government has to input many resources for aiding or reconstruction, e.g., police force, fire control, aid worker, resources used for resisting flood, etc. This also brings loss to society.
2. Environment
Traffic
Flooding will lead to the damages of roads, collapse of bridges or traffic congestion, which may affect the daily operation.
Damaging the farmland
Flooding brings too much water which will cause damage to farmland.
3. Human Beings
People died and lose their homes
Flooding will cause death and injuries. In year 1998, 0.23 billion of people were affected in the flooding of Xian, including 3 thousands people dead, 1 million of people lost their homes. In 1996, the monsoon flood in India affected more than five million people in the northern and eastern part of the country. Severe floods have also killed some 200 people in India and Bangladesh and left millions homeless and starvation.
4. Disease
Flooding usually brings infectious diseases, e.g. military fever, pneumonic plague, dermatopathia, dysentery, common cold (type A), breakbone fever, etc. And for those areas which have no electric supply due to flooding, food poisoning may occur as food may not be properly frozen.
Preventive measures
1. Improve drainage efficiency
• Construct pumping stations, water gates, tunnels.
• Making sure that gullies work. o Road gullies should be checked and cleaned frequently to ensure that they are not blocked or collapsed. Where there is a large area feeling towards a low spot, this area should be checked to ensure that there are adequate gullies and that they are effectively taking the water.
2. Construction of structures
• Flood barriers are effective means to stop excessive amount of water rushing into low grounds.
• For example, Bangkok. o In Bangkok, the Department of Drainage and Sewerage has a massive construction program of building flood barriers:
a. Flood barriers were built along the Chao Phraya River. It has a total length of about 88 kilometers completed. It will have barrier range from 2.5 to 3 meters above mean sea level.
b. They have elevated the Eastern King’s dike.
c. Along the northern side, construction of flood barrier along Klong Mahasawad in Thonburi.
3. Increase areas serve as retention basins
• In some of the existing water retention basins, although the capacity of draining water from the area is enough in normal circumstances, in time of excessive rainfall, it is necessary to allocate areas to be used as retention basins for detaining such amount of water to prevent flooding in low areas, road, and streets.
• Bangkok is running a very successful program in the Monkey Cheek Area. It involves a public as well as private water retention programs. o Private Monkey Cheek is a small retention basin in private land to detain water from houses and housing villages by specifying in the BMA regulations and promoting cooperation from the private sector. o Public Monkey Cheek is large area to detain large amount of water from canals. Presently, there are Monkey Cheeks available to detain water of about 7 million cu.m. the remaining areas to further accommodate 6 million cu.m. of water has to be acquired as soon as possible.
4. Mitigation measures
• Land owner must not construct bridges, fences or other permanent structures across watercourses nor should they restrict the flow capacity by constructing erosion protection within the channel. Nothing should be stored on the banks in such a place or way that it may be washed away or fall in.
• Watercourses must not be used to dispose of debris, even seemingly innocuous materials such as grass cuttings. Such debris may combine with wind blown debris, twigs, etc. to cause blockage of grills and thus a flooding incident.
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Human Causes
Population pressure
Because of large amount of people, more materials are needed, like wood, land, food, etc. This may aggravate the problems of overgrazing and over cultivation. And soil erosion happens more often, it increases the risk of flooding.
Human Causes
Poor Water Management
When the dams are poorly constructed or maintained, they may easily collapse and this results in flooding. Such as more than 240 people were killed and 150 were listed missing after a dam burst in China's northwestern Qinghai province.
In 1938, the Chinese army broke the dyke of the Huang He at Fa Yuan Kou. Water flooded huge area of land. The aim of breaking the dyke was to stop the Japanese army from moving forward.
Deforestation
Large areas of forests near the rivers have been cleared. The lands use to make rooms for settlements, roads and farmlands. Less vegetation protect the soil, the soil is quickly lost to rivers and sea. This raises the riverbed, so the river overflows its banks easily.