Johannesburg stormwater management

The promise and peril of stormwater management in Johannesburg

Founded in 1886, Johannesburg is one of the world’s youngest major cities. The metropole grew up fast, however, quickly taking on enormous proportions – both in size and impact. Expanding from a tented camp, to a town of tin shanties, it soon morphed into a city of modern skyscrapers. Today is the commercial, industrial and financial hub of South Africa.

Johannesburg
Joburg.

Stormwater in a city of Joburg’s proportion is no joke. I lived there once – it’s a beast! In the suburbs there are many trees, but is covers vast areas of grey and hard surfaces. Towards the centre, the belly of the beast is filled with cement, tarred roads and buildings. The way the city is built dictates the route that rainwater takes once it hits all these hard surfaces. In Cape Town, the 21 catchments that city sits on dictates how stormwater is managed there. Durban, again, is located right at the bottom of a catchment, between the mountains and the sea, which shapes the route of rainwater there.

To understand the promise and the peril of stormwater management in any city, you have to understand its location. Let’s look at Johannesburg.

Where Joburg gets its water from

Joburg straddles a major watershed, the Witwatersrand. From here rivers flow either into the Indian Ocean to the east, or to the Atlantic Ocean in the west. Drinking water for the city’s 4 million plus people is imported (purchased in bulk from Rand Water). It’s pumped about 50 km from the region of the Vaal River.

This source, again, is supplemented with water transferred all the way from Lesotho via the Lesotho Highlands Water Project – Africa’s largest ever water transfer project.

One of Johannesburg's conspicuous water towers.
One of Johannesburg’s conspicuous water towers

Rain on the city itself usually falls in short, sharp showers in the summer (between September and April). The area is renowned for impressive thunderstorms and sometimes, explosive hail makes Joburgers run for cover.

Stormwater management in Johannesburg

As with other cities, the approach to stormwater in Johannesburg has been to send the water away as quickly and efficiently as possible. Here, it happens via a combination of man-made infrastructure and natural features. The water is sent towards 12 river systems and 106 dams within the municipal boundaries. This is complimented with detention or retention ponds, as well as wetlands and other natural features that retain water.

The meteoric rate of development has not been without consequence. In particular, the stormwater system and the environment that it is sent to, are showing the strain.

The state of stormwater in Johannesburg

The entire system is described as being under severe stress. For some time already, many parts of it have been functioning close to or beyond peak capacity.

Poor maintenance and budget constraints contribute to the crisis. Estimated annual clean-up costs associated with rain and stormwater (as reported in 2007/8) has spiraled to R25 to 30 million. The bulk is for clearing of stormwater drains from major blockages. Mostly, its blocked by mountains of litter.

Most natural features like rivers have been severely degraded over the years. Wetlands have been progressively filled and drained to make space for the ever increasing demand for urban development.

In addition, portions of streams have been canalised to try and improve their degradation. All surface water quality within the city has been severely affected by the growing city, its blocked sewers, aging infrastructure and the sea of litter transported by the stormwater.

Johannesburg stormwater system.
The Jukskei River, now a polluted and canalised stream that flows through the back-alleys of Joburg.

For Joburg, times of drought, times of floods

As the hard surfaces in the city grew, the runoff patterns and peak flows of rivers in Joburg have were dramatically altered. Though the city suffers from water scarcity at times, it is thus also familiar with floods.

Already, the problems associated with the quantity and quality of stormwater in Johannesburg has a substantial, detrimental knock-on impact on the health and safety of the people that live there. The infrastructure will take more punches due to climate change. This is likely to aggravate existing issues, including increased volumes of stormwater and flooding overloading the already overburdened system.

The people that run the city are not unaware of the situation. The alarm has been raised long ago. Many reports have highlighted these, serious concerns regarding the city’s stormwater (and sanitation) systems.

The potential that lurks in the stormwater system

However, where there are big challenges, there is large room for improvement. For Johannesburg this is encapsulated in policies that are laying the groundwork for water resilience through stormwater management.

“Stormwater is an untapped resource that can help to offset drinking water supply or supplement and reduce the pressure on the stormwater system downstream”, says Jane Eagle, the City of Johannesburg’s Deputy Director for Open Space Planning, that falls under the Department of Environment and Infrastructure Services.

Jane Eagle talks Johannesburg stormwater management
Jane Eagle, the City of Johannesburg’s Deputy Director for Open Space Planning

“To me it is underrated, and offers many solutions,” she says. The flagship work that has been done in this regard in Johannesburg is encapsulated in the stormwater bylaw and draft design manual.

Laws and regulations for stormwater management in Johannesburg

The Stormwater Management By-laws were promulgated in 2010, and addresses some of the key issues regarding stormwater management in the city.

The recent Stormwater Design Manual takes these further and emphasises the retention and attenuation of stormwater at source. It stipulates that the developer must attenuate runoff if the development covers more than 500 m² with impermeable surfaces.

The draft Stormwater Design Manual Guidelines provides detailed requirements for stormwater attenuation and for discharge into the receiving environment. The city has also just embarked on a feasibility study for regional attenuation for supplementing water supply.

Light at the end of the stormwater tunnel

“We are making headway,” says Jane. The stormwater design manual contains “quite revolutionary stipulations”, including requirements for attenuation at all scales. Further, it ensures that runoff meets certain quality standards, reducing the negative impact on the receiving environment and improving the health of the city’s rivers.

In this way, sustainable stormwater management is also seen as key to creating a more resilient Johannesburg in the face of climate change. This includes the basic principles of increased infiltration to decrease runoff and reduce the impacts of floods.

Sustainable stormwater management system in Johannesburg
Walkways that let water through, allowing it to infiltrate into the soil

Critically, the guidelines also addresses the quality of stormwater generated by a property. “It gives you the option to look at complex filters contained in natural systems and green infrastructure,” says Jane. “We are making a call for more green solutions which mimic natural systems,” she says.

Hurdles in the way of change

However, though the groundwork has been laid by the Stormwater Management Bylaws, among others, the benefits have been hampered by slow implementation. Jane says there are a number of challenges to overcome to ensure that there is compliance.

For one, implementation of the policies is held back by a fragmented institutional model, as the provisions need to be applied by both the Johannesburg Roads Agency, as well as Environment and Infrastructure Services Department.

Not only are roles and responsibilities unclear, but the mandates are often conflicting. Traditionally, stormwater was regarded as only the domain of roads departments or entities. They have the responsibility to keep the city safe from flooding, and to ensure that stormwater is efficiently conveyed off sites and roads.

Increasingly, however, stormwater is a concern also for Environment and Infrastructure Services because of the substantial impact that stormwater has on the receiving environment and natural systems. “Building relationships are important, but this requires ongoing effort” notes Jane.

Another challenge is a lack of knowledge on the bigger- scale application and impacts. There is also a lack of skills and experience both in-house and within the profession to correctly apply this. Pilot sites to test and demonstrate effective application of concepts are necessary, but currently lacking.

Blocked stormwater management system in Johannesburg
A blocked stormwater drain in the streets of Johannesburg

A range of roleplayers also need to be brought on the bandwagon. “Engineers, architects and property developers need to be convinced of the validity and co-benefits of these concepts and then take the baton and run with it,” says Jane. There is thus also a need for champions.

The status quo is not an option

The transformation of mindsets is key to transforming stormwater management in Johannesburg.

“I’m not saying sustainable stormwater management is easy,” says Jane. “The question is rather, if we take the rate of development, the increased scarcity of water, and the lurking dangers hidden in our current urban infrastructure in mind, if we can afford not to try.”

Notes

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