ONE could be forgiven for thinking that urban drainage is a dry topic.
However, for a society becoming increasingly environmentally conscious about how we manage and preserve natural resources, it is a very timely issue, especially with the high rate of urbanisation and development taking place all over Malaysia.
Historically, most of the urban developments in Malaysia adopt the concept of “rapid disposal” – channelling excess stormwater away from the source to downstream, usually through a network of concrete drains and the utilisation of existing river systems.
But unchecked urban development and inefficient, fragmented drainage networks are among the main culprits why certain areas such as the Klang Valley are so susceptible to flash floods. In urbanised areas, there tends to be greater surface area covered by non-permeable materials such as concrete and road surfaces — meaning less rainwater gets absorbed into the ground.
In addition, there is also less natural cover such as trees to help contain excess rainwater and prevent soil erosion.
Heavy downpours over these urban areas often translate into large amounts of stormwater getting channelled into drainage and river systems which often lack the capacity to cope with the sudden surge of stormwater – resulting in flash flooding.
It is relatively easy for the average person to understand the benefits of a good urban drainage system as a public health and safety measure and in terms of environmental welfare.
However, in reality, in Malaysia, there is a lot of room for improvement in terms of adoption and enforcement.
Among major hurdles towards better urban drainage systems is a general lack of subject knowledge, grey regulatory areas, and need for better coordination among various agencies.
Not well understood
“Urban drainage is a subject not well understood, even amongst practitioners,” said Professor IR Dr Mohamed Nor Mohamed Desa from the Centre for Stormwater and Geohazard Management at Universiti Tenaga Nasional (Uniten).
According to a paper titled “Current Trends in Integrated Urban Stormwater Management Practice in the Tropical Region Malaysia” which he co-authored with colleagues Professor Dr Lariyah Mohd Sidek, S Ahmad Husaini, TM Leong and A Anita (Mohd et al), the need to set out urban drainage standards and procedures locally was recognised as early as 1975 when the first urban drainage manual was published in Malaysia.
This was followed by the Urban Stormwater Management Manual or Manual Saliran Mesra Alam (MSMA), endorsed and gazetted by the government in 2001, making it compulsory for any entity or organisation wanting to develop a piece of land in West Malaysia to follow procedures and techniques as spelled out in the manual.
However, Dr Mohamed Nor highlighted that in its original form, the manual had its shortcomings as it was originally a compilation of various practices carried out overseas and had limited applications in Malaysia because of different climate conditions, rainfall and hydrology.
In an effort to bridge this gap, the Department of Irrigation and Drainage (DID) Malaysia has, over the last 10 years, been constantly developing and improving the manual into a set of standards for engineers and developers to follow.
Moreover, local researchers and universities have also carried out studies to expand current knowledge bases, using local case studies and data.
Despite this progress, Dr Mohamed Nor and Dr Lariyah acknowledged much more research and development needs to be done and more funding allocated towards advancing local scientific knowledge and practical applications.
There is also a need for the DID to update current urban drainage guidelines and procedures to incorporate the latest “control at source” approaches towards stormwater management which utilises detention-retention, infiltration and purification processes with the aim of maintaining runoff quantity and quality at pre-development levels, as put forward in Mohd et al.
Kuching under water?
Although it is compulsory to adhere to the MSMA in West Malaysia, developers in Sarawak are not legally bound to follow the manual’s guidelines and procedures as the state government has yet to adopt it, said Alan Tan, state Deputy Director of Department of Irrigation and Drainage (DID), adding that the department has already submitted the proposal to the ministry.
Meanwhile, he said, the department is using indirect methods in trying to encourage developers to adopt more environmentally friendly practices as contained in MSMA.
“On our part, as a (government) agency, we go through the drainage systems submitted by the developer and try to impose certain conditions that they have to fulfill and we will check the requirements,” Tan explained.
“Although they are not bound to comply, we try to encourage them to follow and do things such as build retention walls and so on.”
He admitted that response from some developers have been less than positive mainly because of the higher costs associated with it.
However, DID counters this by trying to get developers to look at it from a practical long-term view.
“For example, we tell them if you build a retention pond in front of your residential area, it can enhance your property value.
“Some developers buy the idea because landscaping nowadays, such as water features, is increasingly a way to enhance property value,” Tan said, adding that developers could also use retention ponds to fulfill part of the requirements for recreational areas in housing developments.
The cost debate
Increased costs mainly arising from the need to purchase more land are often cited by developers as the main sticking point which prevents them from incorporating “control at source” urban drainage practices into their development projects as they will either have to absorb the additional costs or pass it on to end buyers.
However, the true cost of “control at source” may actually be more optimistic than that.
Dr Lariyah pointed out that if carefully designed and properly incorporated from the start of a project, “control at source” could actually be cheaper than conventional concrete drains.
She cited her personal experience during her time at Universiti Sains Malaysia (USM) where she was instrumental in getting a “control at source” drainage system implemented for the campus which followed guidelines set out in the MSMA manual. The system included the construction of retention ponds and wetlands.
“Total cost was about 10 per cent less than having the normal conventional concrete drain,” she said, adding that she has also heard some developers experienced even higher rates of cost savings, depending on the project.
Dr Lariyah echoed a point brought up by Tan that higher costs could be mitigated by the increased environmental and aesthetic values.
“In West Malaysia, most of the developers’ costs are higher because of land costs. They try to charge higher in terms of property value but they compensate for that in terms of aesthetic value because it blends with the landscape and looks environmentally friendly and greener.“
To add clarity to the cost debate, Dr Lariyah said Uniten is currently doing a study on operation, maintenance, and life cycle cost to make a comparison between the different components of MSMA and conventional drainage practices.
However, data has been difficult to come by as most of the developers and contractors they have approached are reluctant to share confidential information about their development costs.
But recalcitrant developers may no longer have a choice in the future about whether or not to implement “control at source” measures.
Dr Lariyah noted that in general, the government was moving towards more sustainable urban drainage and stormwater practices such as the recent directive making it compulsory for developers to incorporate rainwater harvesting into future housing projects.
Tan from DID said it makes good sense for the government to implement such pre-emptive measures as it would cost the government even more in the long run to be retroactive and they would end up shouldering heavy costs to build more drains, desilt rivers and so on.
“The key word here is ‘sustainability’, Dr Mohamed Nor stressed.
“I’m a firm believer of this system (control at source). We have to think of costs in terms of future generations. I can see the popularity of this approach is increasing in the country. There are lots of new housing areas which implement integrated urban water management facilities such as wetlands, retention ponds, park areas, and recreational areas such as the Botanical Gardens in Klang and Bukit Jelutong.”
He added that although these areas were very expensive, people still sought them out because they appreciated the environment.
He predicted that the number of properties practising integrated urban water management would increase despite the heavy capital expenditure because people realised it actually cost less in terms of social and environmental value in the long run.
Coordination and enforcement crucial
Even if MSMA were adopted in Sarawak, it probably won’t be enough on its own to ensure that urban drainage issues would receive the appropriate level of attention it warrants without strict enforcement by governing bodies and the support of developers and industry associations.
Going by the many parcels of land he has observed being developed around Kuching, Dr Mohamed Nor cautioned that residents here may one day face similar problems as Klang Valley if drainage systems are not properly integrated and maintained to deal with excess runoff.
“In a housing area in the peninsula, you can see up to 10 developers developing small parcels of land — so the problem of drainage is a big issue,” said Dr Mohamed Nor, citing Cheras as an example where there is a big sign board with the names of 30 taman (housing developments).
With so many different developers and different developments covering a relatively small area, coordinating and integrating drainage systems can be frustrating and problematic.
Putting an effective integrated urban drainage and stormwater management system in place requires a goliath undertaking in terms of cooperation, coordination and communication between various federal, state and local government agencies and regulatory bodies as well as with the private and public sector stakeholders such as housing developers and water utility operators.
Unfortunately, despite good intentions, progress is painfully slow as there remain many areas of conflict in terms of regulatory jurisdiction and enforcement which have to be ironed out.
However, urban drainage is an issue which modern society can ill-afford to delay tackling because the longer it is left unresolved, the more difficult and expensive it will be to undo its causes and rectify its effects.
“The cost of managing an urban water management system is ever increasing in tandem with the rate of urbanisation, not just in Malaysia, but worldwide,” Dr Mohamed Nor said.