If there are two constants in the Klang Valley, they must be traffic jams and flash floods. The first would be a Leader for the future, but for now, it is flash floods and how to tame them. And taming floods comes with its own wisdom.
Know the causes of floods and the terrain you are working with, says former National Water Research Institute director-general Datuk Nor Hisham Mohd Ghazali. Consider the causes of floods in Kuala Lumpur. The city has a network of outdated drainage systems that is just not made to handle punishing rainstorms.
With climate change bringing with it extreme weather, when it rains in Kuala Lumpur, it pours. It would be unfair to say that our city planners didn't consider the future in mind. They did, but the future happened too quickly.
Give this system a rain of 360mm as it happened on Dec 18, 2021 — a month's rain in 24 hours— and deluge is the result. According to Nor Hisham, there isn't a drainage system in the country that can handle this. Moreover, a 24-hour downpour of 600mm, as shown by rainfall records from the east coast of Peninsular Malaysia and in Sabah and Sarawak, is unmanageable.
If our past city planners didn't plan for such a downpour, our future ones must. They must take a leaf from our oil industry's book, which builds its offshore installations to withstand a 50-year or even a 100-year storm. But cost can be prohibitive, especially for a nation with a debt of RM1.5 trillion.
The way we treat our rivers does not help. We turn them into dumpsites, choking them with rubbish of all kinds. If this is not enough, we do the same to our monsoon drains.
As water quality modelling expert Dr Zaki Zainuddin once put it to this Leader, many Malaysians don't have the "heartware" to let rivers be just rivers. With such a load, rivers can't empty fast enough for floods not to happen. Made to carry only water, our rivers are forced to be landfills. Excess water needs to be diverted elsewhere.
This is where the two planned underground reservoirs come in. But Kuala Lumpur sits on limestone, and, more accurately, floats on it in some places. This is what Nor Hisham means by understanding the terrain.
Limestone formations are a difficult material to work with, says the engineer. "They pose numerous engineering challenges. One such is the fractures that they come with. If the fractures are not sealed, they won't work."
But we must if we are to tame the flash floods, especially with the Klang Valley running out of above-ground space. To Nor Hisham, underground reservoirs are the way to go, though cost will be a concern.
As this newspaper reported on Tuesday, reservoirs are crucial in flood management — be they above ground or underground — as they can reduce river or rainwater flows by 40 per cent during heavy rain.
There are 33 flood reservoirs in the Klang Valley now, but the climate change-induced downpours of the recent past tell us that more are needed to avoid a recurrence of the flash floods of those from August and Oct 15.