More must be done to prevent floods

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  • Tuesday, 13 Jan 2015

Urban flood woes: Local authorities must monitor drainage in the city to prevent the occurrence of flash floods in urban areas.

AFTER more than 30 years, we recently encountering massive flooding in the country with more than 100,000 people evacuated throughout Malaysia. The North-East monsoon displayed its full strength, devastating the east coast and southern regions of peninsular Malaysia.

Unfortunately, flash floods can develop in just a few minutes of rain and floods can be local, impacting a neighbourhood or community, or very large, affecting entire river basins.

Localised heavy monsoon rains from a series of storms moving over the same area causes flooding when the rate of rainfall exceeds the drainage capacity of the area. When this occurs on tilled fields, it can result in a muddy flood where sediments are picked up by run off and carried as suspended matter.

Rivers may also rise to flood levels at different rates, from within a few minutes to several days, depending on the type of river and the source of the increased flow.

Rapid flooding events, including flash floods, more often occur in smaller rivers, rivers with steep valleys, and rivers that flow for much of their length over impermeable terrains.

Meanwhile, coastal areas may be flooded by storms at sea, resulting in waves over-topping defenses or, in severe cases, by tsunami or tropical cyclones.

Urban flooding, on the other had, occurs in a built environment, particularly in more densely populated areas, and is caused by rainfall overwhelming the capacity of the drainage systems, such as storm sewers.

Although sometimes triggered by events such as flash flooding, urban floods are a condition that causes systemic impact on the community, such as those in Cameron Highlands, Kelantan, Terengganu, Johor, Perak and some parts of Selangor.

The primary effects of flooding include loss of life and damage to buildings and other structures, including bridges, sewerage systems, roadways, and canals.

Floods also frequently damage power transmission and, sometimes, power-generation facilities, which then has a knock-on effect caused by the loss of power. This includes the loss of water treatment and water supply, which may result in a lack of drinking water or severe water contamination.

It may also cause the loss of sewage disposal facilities. Lack of clean water combined with human sewage in the flood waters raises the risk of waterborne diseases such as typhoid, giardia and cholera, depending upon the location of the flood.

The rampant damage to roads and transport infrastructure may make it difficult to mobilise aid or to provide emergency health treatment. Aid in the form of air-drop assistance via helicopters is available but this can only help done to a certain extent

Floodwaters typically inundate farm land, making the land unworkable and preventing the planting and harvesting of crops, thus leading to shortage of food for both humans and animals. A country’s entire harvest can be lost or destroyed in extreme flood circumstances and some tree and plant species may not survive prolonged flooding.

The east coast of peninsular Malaysia will face severe economic hardship due to a temporary decline in tourism, rebuilding costs and food shortages leading to price increases. Such an impact may cause psychological harm to those affected, in particular where deaths, serious injuries and loss of property occur.

While floods are not new in Malaysia, it is important that the Meteorological Department has the techniques to anticipate such disasters and provide forewarning to the people in order for precautions to be taken and lives to be saved.

For instance, farmers will be able to relocate livestock to higher grounds and harvests can be made early. Emergency services can also be on standby and medication as well as first-aid prepared ahead of time.

Those affected will be also able to prepare better for the floods. Such pre-warnings will produce fewer casualties and save more lives.

In order to make the most accurate flood forecasts for waterways, it is best to have long-term historical data relating to stream flows to measure past rainfall events. By combining historical information and real-time knowledge about the volumetric capacity in catchment areas, more accurate flood forecasts can be made.

Radar estimates of rainfall and general weather forecasting techniques are also important components of good flood forecasting. In areas where good quality data is available, the intensity and height of a flood can be predicted with fairly good accuracy and plenty of lead time.

In many countries around the world, waterways prone to floods are often carefully managed. Defences such as detention basins, piers, bunds and reservoirs are built to prevent waterways from overflowing.

Flood controls, such as dams, can be built and maintained over time to try and reduce the occurrence and severity of floods as well. In the US and China, the army maintains a network of such flood control dams and we can also do this in the east coast.

In areas prone to urban flooding, one solution is to repair and expand man-made sewer systems and stormwater infrastructure. Another strategy is to reduce impervious surfaces in the streets, parking lots and buildings through natural drainage channels, porous paving, and wetlands.

Areas identified as flood-prone can be converted into parks and playgrounds that can tolerate occasional flooding. Legislation can be adopted to require developers to retain stormwater on site and require buildings to be elevated, protected by floodwalls and piers.

Property owners can also invest in solutions themselves, such as landscaping their property to divert the water-flow, and installing rain barrels, sump pumps, and check valves.

It is imperative that floods should be controlled in an effective manner. More money must be allocated to obtain state-of-the-art equipment to anticipate the floods; proper mitigation measures like reservoirs, buns, piers and dams must be constructed to contain this natural mishap that drains our natural resources.

Illegal logging and improper development must be controlled. The silt from illegal logging and haphazard development causes the streams and rivers to be heavily silted thus causing heavy overflowing.

The local authorities must step up monitoring of all drains in housing estates and cities to ensure the drains are in top condition. They should also try to increase the capacity of these drains.

The occurrence of floods is not something new to our nation. In fact, it is an annual occurrence in some places yet nothing has been done to improve the situation.

Every year, the nation cries at the devastation, sympathises with the victims and mourns the loss of loved ones swept away in this tragedy.

Enough! Instead of spending millions rebuilding, the government should allocate their budget and focus their efforts on preparing and protecting the nation from this natural disaster.

It is unacceptable and incomprehensible that a country wanting to join the ranks of developed nations has overlooked the basic needs of safety for its people. All concerned parties must come together to find a solution to this phenomenon and protect the people and the nation.

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