AECOM’s Associate Director of Sustainability, Michael Henderson, considers the environmental and economic benefits of effective water management in urban areas.

Green spaces provide key to alleviate urban flooding

It’s hard to see any good coming out of the flooding that has devastated parts of the UK over recent months. But once the waters have receded, there must be a clear focus on how to prevent similar disasters in the future through effective management of our cities’ water systems.

Michael Henderson, associate director of sustainability for AECOM, welcomes this opportunity, and says there are wider issues to be considered; issues that are vital to both the environment and the health of our local economies. By taking a more holistic approach to water management, one that incorporates more than just flood defence measures – what AECOM calls “Water Sensitive Urban Design” (WSUD) – UK cities and local authorities will also gain from an array of economic benefits.

Whilst developers will soon be mandated to incorporate use of more permeable materials into new urban landscapes, due to the Flood and Water Management Act of 2010, Henderson says that the Act only goes so far with its focus on new build projects and not on addressing the current design problems found within our urban areas.

As Henderson explains, “The Act requires the development of new standards for sustainable drainage which – after a lot of toing and froing – is due to be published imminently. In essence, it requires that new urban landscapes are designed with areas that can control runoff, thereby slowing its progress to rivers and drains.

“However, there needs to be a greater emphasis on retrofitting areas. AECOM has been exploring the business case for incorporating more green spaces into urban landscapes at the early design stages of regeneration, and the figures really do stack up,” he reports.

“For a start, the cleaner the water is, the lower the energy cost of treating it for local reuse or discharge into our rivers. Moreover, if the UK can clean up its waterways, it will be liable for fewer fines under the EU Water Framework Directive, bringing another financial incentive to pursue this strategy.

“In addition, there is evidence to show that productivity increases when people look out over a green area, and other benefits like improved health and wellbeing are also detected. Finally, property prices tend to be stronger in more aesthetically pleasing surroundings, giving a helpful stimulus to the local economy.”

Of course, an increase in the number of green spaces in the urban landscape speaks to one of the clearest advantages of such an approach to water management: namely, its environmental benefits. These spaces can provide storage or infiltration and, in turn, slow down the progress of water to urban spaces.

“By reducing the speed of overland flow in the urban environment, greater use of green spaces can actually help to improve water quality in rivers,” Henderson continued. “That’s because water that passes through certain plants and soil structures is cleaned – so by the time it reaches a waterway, it has already had some filtration.

“The problem with urban landscapes is their predominant use of hard, non-porous materials, which do nothing to slow the progress of water towards the drainage system,” he states. “As a result, sewers can rapidly become overloaded, resulting in flooding and pollution of our waterways – water in which we extract a significant portion of drinking water from – through combined sewer overflows.”

Overall, Henderson concludes, WSUD provides a way of responding to some of the challenges highlighted by the recent floods. “We won’t solve the problems affecting individual communities overnight,” he observes. “But that shouldn’t stop central and local government taking a lead on more holistic water management, to protect the environment and drive economic growth.”


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