Universiti Putra Malaysia’s civil engineering senior lecturer Balqis Mohamed Rehan agreed flood walls would be far more effective than the sandbags DBKL uses as a temporary measure because of their structural properties.

“Unlike sandbags, the walls are designed to be watertight and have rigidity.”

However Balqis said the effectiveness of a flood wall depends on the type to be used, which can be either permanent or removable.

“Permanent flood walls would be the most effective in terms of safety because they are usually made of concrete and do not need deployment during flash floods.

“The only disadvantage is that the aesthetic value of the surrounding environment could be permanently lost,” she said.

On the other hand, demountable flood walls are panes of lightweight yet durable materials such as steel and plastic that can be removed when not needed.

“But this type can only withstand up to a certain flood depth, so anything above this and the panes may slide down due to the high fluid pressure,” Balqis said.

On Sept 18, mayor Mahadi Che Ngah said DBKL was looking for a suitable design for flood walls.

Disaster preparedness and management expert Khamarrul Azahari Razak of Universiti Teknologi Malaysia advised against rushing to design and build the flood walls even though the monsoon season is nearing.

“There must be no design or construction flaws otherwise the walls will collapse and that will defeat their purpose.

“A long-term preventive scheme will (also) be required post-construction,” he added.