Most of my career has been focused on sewerage, drainage management and flooding, especially in the urban environment. I have worked with teams globally to deliver flooding solutions for our clients. However, the impact of extreme rainfall events still causes major disruptions to our lives and regular loss of life. In tropical and sub-tropical areas increasingly the temperate areas, flooding of urban areas appears to be becoming more frequent. With the significant increase in population living in our urban areas, the emergence and increased number of ‘mega’ cities the risk of flooding and its impact is becoming more acute. Combining this with the impact of climate change, suggests living with flooding is to become more and not less frequent.
The solution? Traditionally, engineering solutions have focused on getting flows out of the built up areas as quickly as possible. With urban areas now spanning hundreds of hectares and the level of run-off increased with urban development, this strategy can no longer cope. There is neither the space nor funding to keep building larger sewers/drains and flood channels. Our traditional pipes and channels have a finite capacity once this capacity is exceeded flooding occurs and often in an unmanaged way.
A different approach is required, one which accepts and works with the urban environment and recognises that not all rainfall can be channelled away from our buildings and roads. For several decades several town planners, architects and engineers have developed visions of an urban environment featuring open areas for public amenity, areas which make the environment desirable to live in. With these and other professionals working together and accepting that we need to make space for water the needs of both people and nature are not just possible but need to be made possible.
This is where both flood management and blue-green corridors can play their parts. By accepting and actively managing roads as flood channels during extreme events, flood water can be kept away from critical assets and infrastructure, by warning the people who need to know the risks of doing this can also be managed. The use of blue-green corridors recognises that moving water away form an area as quickly as possible is not necessarily a good approach. By creating numerous pockets of green space which can be used to temporarily store floodwater retaining and slowing the movement of water spreads and reduces the impacts of flooding. When these areas hold the water in a managed way, we can minimise the impacts of flooding while working with our environment to produce pleasant places to live.
While we will need to keep maintaining and improving our traditional conveyance systems, we also need to look at what happens once this is exceeded, develop strategies and design our urban landscape to manage extreme flooding events above ground.
What do you think? Tweet to us at @MWHGlobal or use #MWHGlobal and tell us your thoughts.
Tony along with Professor David Balmforth (Executive Technical Director) of MWH presented this similar topic at the MWH Water Dome during Singapore International Water Week. Their theme: flooding, the consequences of flooding and how we can best manage extreme flooding events when they occur.
