by David Balmforth
Conventional drainage solutions have served the needs of the developed world well, providing a high level of public health. However, in the context of population growth, urbanisation and climate change, the escalating cost of increasing capacity is proving prohibitive. If the additional demands of environmental regulation are factored in, traditional approaches become unsustainable.
This decade will mark a paradigm shift in thinking in urban drainage. Already we are seeing the “spring” of change, perhaps not in the Middle East, but certainly in pockets of the developed world. Roof drainage disconnection and rainwater barrels in the USA, dual use flood storage areas in Japan and Sweden, rainwater harvesting and source control in Australia, and “water streets” in the Netherlands. Urban drainage is being seen in a wider context, from source through pathway to receptor. In the UK this will shift the emphasis away from underground piped systems.
We will see source control measures retrofitted into urban areas – what works for new development will be made to work for existing systems. There will be some enhancement of conveyance capacity, but attention will turn more to extreme events and the management of residual flood risk. Thus roads will become temporary conveyance channels and parks and open space “dual use” sacrificial flood storage. Development will be relocated away from flood risk areas and buildings made more resistant to floods. Local Authorities might be seen as the engines for change, especially with their new Lead Flood Authority responsibilities. Yet funding is likely to prove a long term barrier. However, there is evidence of a growing appetite amongst water companies in England and Wales to act as the catalyst for change.
All future infrastructure will have to operate in an environment subject to climate change impacts, larger populations, scarcer water resources and high energy charges. Systems will become less rather than more centralised. Storm water will become an important resource, as a secondary local supply. More wastewater will be treated locally rather than moved long distances to centralised treatment plants. Systems will be operated dynamically with rapid response to defects as and when they arise. Urban drainage will be integrated into urban design to make our urban areas better places in which to live. The work of the drainage engineer will change beyond all recognition.
For more information, contact David.
