Understanding and managing flood hazards in Malaysia
by Dr. Afroz Ahmad Shah
A hazard, natural or artificial, is a process that includes events that could pose danger to infrastructure and human lives. Risk measures the intensity of destruction associated with a hazard and destruction is the measure of devastation caused by a hazard.
Malaysia is quite prone to floods and landslide hazards, but floods are the major hazards that cause significant destruction. This is mainly related to excessive rainfall over a period of time, which means that surplus water floods river channels and banks and often breaches some portions of the river channels during such events.
There are 189 river basins scattered throughout the geographic extent of Malaysia. These rivers and their banks are a source of water for agriculture and preserve a variety of animal and plant life and often add to the overall beauty of this tropical land, ornamented with some of the world’s most beautiful rainforests.
However, often, these rivers could adversely affect both human lives and structures during flooding which is becoming a huge problem to manage.
Recollections and records of flooding in Malaysia are dispersed throughout its history and some recorded data suggest that major flooding occurred in 1886, 1926, 1963, 1965, 1967, 1969, 1971, 1973, 1979, 1983, 1986, 1988, 1993, 1998 and 2005. The devastation caused by recent floods in December 2006, January 2007 and December 2014 is yet another reminder of the colossal loss linked to such hazards.
The total cost of devastation varies with the intensity of the disaster. For example, it was estimated that the January 1971 flood that happened in Kuala Lumpur and several states resulted in a loss of more than RM200 million and the death of 61 people. It was declared a national disaster by the then Prime Minister.
Similarly, the 2006 to 2007 floods in Johor caused some RM1.5 billion in damage. The 2014 to 2015 flood disaster that hit certain parts of Malaysia, particularly Kelantan and Terengganu, caused extensive damage and over 200,000 people were affected with 21 casualties.
Flood disasters in Malaysia is not a new phenomenon and the relevant authorities could have largely avoided the direct losses to human life and property to a great extent. Although various measures have been taken by the authorities to understand the flood hazards and implement a timely remedy, the mitigation of a crisis is impossible without thorough and comprehensive scientific research.
Having said that, a new research planning and strategy is required. It should adopt a systemic methodology to examine the cause of flooding where high-resolution satellite data is used along with meteorological data. This should be followed by extensive field investigations at selected locations where river channel morphology, topography, sediment transport, siltation process and geomorphology is investigated.
Such an approach requires a multidisciplinary team of experts including geologists, geomorphologists, meteorologists, civil engineers and experts in geoinformatics and hazard management. The team would be able to establish scientifically exhaustive data sets that will serve as guides in the preparation of diagnostic flood hazard maps which can be used to get some sense of the flood hazard problem.
Furthermore, through extensive interaction with the affected communities, a comprehensive database can be compiled to be analysed in Geographic Information System (GIS) and statistical software environments. This whole exercise will yield scientifically sound and credible flood hazard and vulnerability maps, which could be used for flood hazard modelling for the whole country.
Such a product could be used by policy makers in Malaysia or in any parts of the world with a similar flood hazard history. Once comprehensive hazard mapping and understanding is achieved, it is only then that flood hazard mitigation plans can be properly organised.
It may take years to properly understand the causes of heavy rains, because weather and climatic patterns are often complicated and are governed by a range of factors. Thus, it is important to focus on planning and organising resources to combat flood hazards, which can only be achieved if one prepares for the worst case scenario in any flood-prone area.
This is similar to earthquake prediction where it may take decades for scientists to understand the exact timing of an impending earthquake. People around the world have learned to live with earthquakes and have established a vigorous scientific and engineering outlook to construct buildings which can withstand earth tremors.
The problem of flood disasters can be partly managed by de-siltation and/or widening of river channels, and diverting the excess waters into other channels. Although this may not achieve the best results, it could minimise the damage to a large extent.
Education also plays an important role in minimising the effects of any disaster. Institutions of higher learning could organise awareness programmes such as short-term disaster management courses or scientific talks to ensure relevant and scientifically updated information is delivered to the community.
Dr. Afroz Ahmad Shah is a former senior lecturer in the Applied Geology Department of Curtin Sarawak’s Faculty of Engineering and Science. The article was previously published in Current Science, Vol. 106, No. 5.