You’ve heard of or have read about the word “floodplain” before, maybe in this site, in news articles, or in any other sites. But what is a floodplain? It is actually a flat area of land that is next to a stream or a river that is frequently or occasionally being flooded. The flat area of land can either be dry or semi-dry area, but as long as water naturally flows in these areas when water levels rise, these areas are considered as floodplains.

The frequent flooding of an area help shape the floodplain itself. But erosion and aggradation are usually the two main elements that create floodplains. There are times when rivers or streams cut deeper into its channel creating a narrow channel with little or no floodplain. There are times, however, that rivers and floodplains have no defined lines. Instead of a clear river bank, the land area on either side of the river or stream is so flat that the water just flow to it from time to time.

Naturally occurring floods from the rivers and streams carry sediments. Depending on the flow of the river, sediments are deposited into the floodplains differently. If the river is both deep and fast, more sediments are carried into the floodplain when the water overflows. Most floodplains are made up of sand, silt, and clay which what rivers normally carry. However, when rivers are really fast, instead of sediments in the form of silt and sand, gravel is deposited in the floodplains. As the river change its position, so do the kind and amount of sediments being deposited.

Mainly due to the rich mineral deposits that are contained in the river sediments, the floodplains support a diversity of ecosystems. Microscopic organisms alone thrive in the organic matter. The decomposition and production of nutrients make the floodplains a vital agricultural piece of land. This is one reason why people form settlements in floodplain areas despite the dangers of being flooded. The land here remains fertile for a long time.

Moreover, people build their homes and even towns on floodplains because water is more valuable in this areas, transportation through the river is cheap, and because it is basically easier to develop a flat land area than a rolling hills one. Because of these reasons, people endure the yearly or more frequent river overflow. To them the danger and inconvenience is worth it.

One of the more prominent floodplains is the one in the lower Mississippi River which is about 16 km (10 mi) across. The floodplain the is fed by the Nile River is another example of a large one.  This one is located in the upper part of the Nile Basin. The Ganges and Brahmaputra rivers in India and Bangladesh have caused countless of problems to the millions of people that live in the flood prone areas. The Yangtze River in China is another large river and large floodplain that supports a huge part of the country’s poor population.

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Flood warnings work best if they remain simple. Placing too complicated definitions behind warning signals only causes confusion among the public. This is why some governments failed in their flood warning systems. Also a factor is the process on how they arrive with specific warning signals. Agencies and other organizations involve in the overall government flood control and warning network might not have understood the full concept of their own warning system causing inadequate or wrong warning information.

Despite the arid and desert-like perception of Australia, its river system can cause major flooding. That’s why the government has instituted The Bureau of Meteorology to provide flood warning services. Their flood warning system is a product of an inter-agency cooperation involving the State Emergency Service (S/TES) in each State/Territory as well as water agencies and local Councils.

The Bureau is responsible in providing a  variety of information including Alerts, Watch or Advice notifications of possible flooding or if flood producing rains are to be expected in the next few days.

They can also issue a Generalised Flood Warning which informs the public if a flooding is occurring or is expected to occur in a particular region. As a generalized warning, it only provides information on the possible or current location of flooding and none on the severity of the floods.

With regards to flood specifics, the Bureau provides Minor, Moderate or Major flood warnings which are specialized warning systems. This time, the warning specifies the the river valley, the locations expected to be flooded, when it is likely to occur, and the expected degree or severity of the flooding.

Minor flooding is defined as floods that cause inconvenience and low-lying areas that are near waterways are expected to be affected. It is recommended that stock and equipment be removed or placed on higher grounds. Also, minor flooding warnings can mean that minor roads would be closed and low-level bridges submerged.

A Moderate flooding warning on the other hand, contains all the possibilities of a Minor warning with the addition of the evacuation of some houses due to the increase height of flood waters. Main traffic roads may be flooded and a wide range of low lying areas would be submerged.

Major flooding involves the extensive flooding of rural areas and even urban areas. Properties and towns are likely to be isolated since major roads are most likely to closed since flood waters have put down underwater. Expect people from flood infected areas needing evacuation.

Aside from the warnings above, the Bureau is also expected to provide information and predictions on the height of the river and its expected height over a time period. If you think about it, this information is very essential since it can determine if how long areas have before the rivers swell and flood their homes.

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People are already saying it,  the recent floods that hit Britain were the worst ones to hit the country in the last 60 years. The floods that happened in late July were a culmination of events that started of months before.

The month of April was the hottest April on record in Great Britain. Most of the country received practically little or no rain for the whole month. Then when June came, rain poured in and it poured in hard. Immediately, dozens of homes in villages like Cornish of Boscastle became waterlogged after  torrential rain.

Then continuous rains cause flooding in Yorkshire, Lincolnshire, Wales, Kent, the West Midlands, Worcestershire, and Northern Ireland. What was thought to be a dry spell became the wettest summer in Great Britain’s history. Flooding across the country resulted to thousands of people needing evacuation and heavy damage on human properties. The flooding that month of June was declared to be a one time event. Again, people’s assumptions and generalizations were later proved wrong.

July 20, Friday marked another first in the history of UK. Almost non-stop torrential rains flooded the roads in London, Dorset Berkshire, Buckinghamshire and Surrey. Hampshire, Leicestershire, Gloucestershire, Wiltshire, Oxfordshire and again the West Midlands suffered severe floods. The amount of water that poured from the sky on that day was great that in some areas the rain pour  was equivalent of a month’s worth.

Rivers across the Midlands began to swell, causing river water to swell towards nearby neighborhoods. The thousands of affected people in the July floods were immediately doubled, or even tripled. In the town of Gloucestershire alone, around 350,000 people were evacuated from the swelling rivers and rising flood waters.

The Friday rains also flooded the center of England putting many more towns submerged or cut off. England was paralyzed together with the towns and villages submerged in flood waters.

After the flood waters and the river ways receded, what was left was more than a million people affected. The final toll was nine dead, millions of people affected, several towns without electricity, and had no drinking water either since fresh water pumps had been overwhelmed by flood waters.

Even if Britain considered the floods these last two months as unprecedented and broke records in the country’s history, they should consider themselves fortunate. When some countries in Asia endures torrential monsoon rains, most often than not the results are huge floods, bigger death toll, bigger number of people stranded or affected, and a bigger total amount of damages. It seems when it comes to calamities, everything else seems to be bigger in Asia.

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According news reports and relief efforts, more than 20 million people have been affected by floods in South Asia due to torrential monsoon rains. Most of the victims and the bulk of the damage can be isolated to two countries, Bangladesh and India.

Bangladesh is one of the most flood-prone countries in the region. An estimated 80 million people are said be vulnerable to flooding each year. India, on the other hand, has not less than 40 million hectares at risk from annual floods from monsoon rains.

Part to blame in Bangladesh’s situation is its geographical location and topography. The country has 230 rivers, of which 57 are international. However, Bangladesh is a lower riparian country and depends on India for sufficient and regular flow of water to its river system that is the source of the country’s economic and environmental survival.

The relationship that that country has with floods is a very fragile one. Almost every year, monsoon rains floods about 20% to 25% of Bangladesh’s total territory. The country’s land area can be divided into five categories which ranges from very low to high elevated lands. Only a small percent of the country is classified as high lands leaving most of the other land types flooded but in different degrees. With very high population, it is only expected to find human settlements in all land categories except in very low land areas.

Being an agricultural country, Bangladesh benefits from flooding since river sediments keep their agricultural lands fertile. However, even though the annual floods provide fertile agricultural lands, a huge percent of the country’s population are situation in floodplain areas resulting to adverse effects on human lives and properties. The extreme flooding that occur in the country continue to take its toll on the country’s economy.

Four kinds of flooding can be found in Bangladesh. The first kind is flash flood which is normal during mid-April just before the start of the monsoon season. The second are rain-fed floods which happens in south-western deltas of the country. River floods come next which is only natural given the number of rivers and water ways the country has. River floods go beyond the riverbanks damaging huge amounts of human settlement territories. The last kind are storm surge floods which happens along the Bangladesh’s coastlines. Sometime, large cyclones can flood the whole coastal belt.

There have been at least eight extreme flood events in Bangladesh’s history where the damage and coverage of the flood affected more or less 50% of the country’s total land area. Those recorded in recent memory include the floods of 1987, 1988 and 1998, each time the flooding lasts from 15 days to 45 days.

Almost the same situations can be observed in India. The southwest monsoon rains cause Indian rivers like the the Brahmaputra rivers to swell over its banks flooding farmlands, rice paddies, and even urban areas.

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I was watching a short video clip the other day which reminded me of how hard-headed and stupid humans can sometimes get. The video showed a lady driving into an obviously deep flooded road. And as expected, her car’s engine stopped where the floodwaters is about knee-deep.

We have seen this kind of situation time and time again. We know that we should not enter flooded roads, especially deep flooded ones, and yet when we are presented with such a predicament we always think that we can outdo the floodwaters. We usually end up stuck and shouting for help like the lady in the video did.

It is fortunate that there was no strong current at the time the lady got stuck in the flood. Two feet deep floodwaters can float vehicles as large as a bus. And add a strong current like those in flash floods and you’ll end up being dragged for long distances by raging floodwaters. This is precisely the reason why we should never drive through flooded roads.

Moreover, with your car being uncontrollably lead by the current, stepping outside the car would be the best choice but the action does not mean you will be safe. A big man can be knocked down quite easily by just 6 inches of rapidly moving floodwaters, so imagine what floodwaters two feet deep can do to you.

Calm, stagnant floods at the most can kill your engine and at the worst case scenario you will be walking back towards a dry place in knee-deep waters. But, flash floods are a different matter. In fact almost half of flash flood related deaths happen in vehicles.

Some tips to remember

When you’re in your car and have prior knowledge of a potential flash flood along  your route or near your present location, it is best to back up or try a different route. Again, never drive through a flooded road or bridge. What you should do is go back and look for another way.

Remember to always stay on high ground. This may be a little difficult especially if you’re in unfamiliar terrain, but try your best to look for routes that go up.

Your car probably has a radio, use it. There are a number of radio stations in that offer weather information including flood updates and news. Keep an ear to flash flood warnings and other news.

In situations where your were able to get out of your car during a flood and the current swept you off your feet, make sure to point your feet downstream and always go over obstacles. Going under obstacle could entangle you resulting to drowning.

And a very important thing, never overestimate your car’s ability to drive through floodwater. Half a foot of floodwater can already reach the bottom of most cars. Just avoid contact with any floodwaters and you and your car will do fine.

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