Kota Kinabalu: Increasingly unpredictable weather linked to climate change is intensifying flood risks in Sabah, but experts say the root causes lie closer to home — in how cities are designed and developed.
Rising temperatures, prolonged dry spells, and sudden bursts of heavy rainfall are often cited as direct consequences of global warming.
Advertisement
X500px(H).jpg)
However, speakers at a recent panel discussion highlighted deeper structural weaknesses in urban planning that may be amplifying these effects.
“The problem is not that we don’t have enough water. We have plenty of water,” said Datuk Ir Ts Dr Amarjit Singh, former Director of the Sabah Water Department, noting Sabah receives among the highest annual rainfall in Malaysia, estimated at around 2,700 millimetres.
“What has changed is how the water behaves when it enters the city,” he said, noting that urbanisation has significantly reduced the capacity of natural landscapes to absorb and store rainwater. Rapid development has replaced permeable surfaces — once acting like natural sponges — with concrete and asphalt, preventing water from infiltrating the ground.
“With the expansion of development, water becomes surface runoff. It flows faster and in larger volumes into drainage systems that may not have been upgraded to handle it,” he added.
The panel discussion, titled “Urban Flood Resilience: Smart Solutions for Climate-Ready Cities,” was held in conjunction with the Plumbing Asia 2026 Conference & Expo, themed “Smart Water, Strong Nation, Sustainable Asia Future.” The forum was moderated by Benjamin Golimbi, President of the SME Bumiputera Chamber of Commerce Sabah (SBCCS).
While drainage capacity is often blamed, Ir Ts Dr Tom Ngui, committee member of the Institution of Engineers Malaysia (IEM) Sabah Branch, said the issue is far more complex than simply undersized drains.
“Urban flooding is usually not caused by a drain that is too small,” he said. Instead, he attributed the problem to the loss of natural storage and conveyance systems.
Urban expansion has narrowed rivers, removed vegetation, and eliminated low-lying areas that once served as natural retention basins.
“In many cases, we expect drainage systems to behave like full river systems, which they were never designed to do,” he explained, describing flooding as “a failure of space rather than a failure of drains.”
Dr Tom added that climate change worsens flooding not necessarily by increasing total rainfall, but by altering its intensity and timing. Rainfall patterns are becoming more erratic, with longer dry periods followed by short, intense storms that overwhelm urban systems.
“Flood risk today is driven by extreme peaks, not averages,” he said.
“We now see intense rainfall within a short period, which places sudden pressure on drains and rivers.”
For coastal cities such as Kota Kinabalu, the challenge is further compounded by rising sea levels and tidal influences. During high tide events, stormwater cannot discharge efficiently into the sea, causing backflow into drainage systems and increasing flood risk. “This is what we call compound flooding, where rainfall, river levels, and tidal conditions interact simultaneously,” Dr Tom said.
Dr Amarjit also highlighted that ongoing development activities, particularly hillside cutting, exacerbate flood risks.
Large-scale clearing of hills removes vegetation that normally slows runoff, while exposing loose soil that is easily washed into rivers and drainage systems during heavy rain.
“When hills are cut and vegetation is removed, water flows down much faster, carrying sediment into rivers and drains,” he said.
“This reduces the capacity of the system and increases the likelihood of flooding.”
Such practices, increasingly visible across Kota Kinabalu and other parts of Sabah, not only accelerate runoff but also contribute to the long-term degradation of drainage infrastructure due to sediment build-up.
Many existing drainage systems were designed based on earlier development conditions and may no longer be sufficient to handle the increased volume and speed of runoff driven by urban growth.
Meanwhile, Ir Lee Tet Fon, Past Chairman of the Sabah Branch of the Institution of Engineers Malaysia (IEM), said the combined pressures of climate change, rising sea levels, and rapid land-use change are reshaping flood risk in urban areas.
Despite the growing focus on climate change, the panel agreed that addressing flooding requires more than adapting to changing weather patterns alone.
“Unpredictable rainfall is forcing a shift from traditional ‘drain-and-dispose’ systems to redesigned urban spaces that absorb, store, and slow down water like a natural sponge,” Dr. Lee said.
