A lifeline for drowning cities

Once again, heavy rainfalls beleaguer Malaysia, and drainage systems have failed to steer the excess water away from townships causing flooding incidents in the states of Terengganu, Kelantan, Pahang, Johor and Perak. At present, over 32,000 people have been evacuated. Meanwhile, the second week of December opened to tragic news at the borders of Pahang and Selangor. A fatal landslide in Batang Kali, near Genting Highlands not only wrecked physical damage to the land, but claimed the lives of many. Search and rescue efforts are still underway.

The unusually heavy rainfall is believed to be a result of climate change, while rampant deforestation in the name of development, deprived the land of its natural flood buffer. In urban areas, this can lead to the accumulation of excessive runoff water channelled to drains and into shared retention ponds beyond the intended capacity, and when compounded by the rapid water level rise due to the tidal backwater effect, it can cause unusually high volumes of water, and result in whole neighbourhoods facing flooding challenges. Urban floods are also exacerbated by the loss of flood storage as a result of development extending into and taking over flood plains and drainage corridors. Add to this undersized or partially blocked drainage systems and siltation in waterway channels from land clearing operations, and you have urban floods.

A key to mitigating urban floods is to create sponge cities. Born from China’s increasing flood woes, a sponge city is one that can hold, clean, and drain water in a natural way – using an ecological approach. So, rather than funnelling rainwater away, a sponge city retains it for its own use, within its own boundaries for irrigating gardens and urban farms or flushing toilets.

Thought leadership is also calling for the creation of flood plains and overflow areas for rivers, which have been used for development due to urban sprawl. This movement calls to restore these floodplains because of their significant role in flood protection, water management and nature conservation, shielding nearby towns from the effects of heavy rainfall.

As urbanisation studies mature, the faculty of built environment see the importance of creating sustainable drainage comprising permeable pavement, sidewalks and gardens. Urbanisation has brought so much concrete to cities it blocks and redirects water to the drainage systems which often become clogged and then the water overflows into the streets and sidewalks, potentially causing floods. The recommendation is to introduce permeable materials such as grass and gardens. This will allow the rainwater to drain into the soil. The process, known as infiltration, also serves to sustain the plant life.

While post-flood financial recovery affects many quarters – from government, insurance companies to individuals, there is also a need to treat flood induced trauma. The nation must build back better and incorporate river restoration, flood plain planning, sponge city approaches and community capacity-building to reduce the severity of future flooding disasters.