Floods, explained
While floods and other extreme weather events such as droughts aren’t exactly new, their frequency and intensity have been increasing in the past years due to climate change. Unfortunately, these destructive natural phenomena are causes of concern almost everywhere in the world.
Storm Babet in mid-October brought exceptionally heavy and widespread rain to the UK. The storm has been the most severe we have experienced this year, affecting thousands of homes and businesses and tragically causing seven casualties.
Floods happen when water soaks land that’s usually dry. Heavy storms might be the most common cause behind them but ruptures in dams or levees, rapid melting of snow or ice and even tsunamis can lead to flooding. Urbanisation also contributes to increasing the flood risk in cities. As the population grows, more buildings and roads are built, adding pressure on drainage systems, and leaving less space for water to soak. Rivers and waterways have also been modified, straightened, and culverted, making them overflow more easily than if they were in their natural states.
Usually, floods can take hours or days to develop, giving residents and businesses time to prepare for potential damage and evacuate if there’s a need. However, they can also evolve quickly and without warning – what we call flash floods. Roads become rivers, and brooks become dangerous fast-moving streams able to sweep anything in their way.
There can be many devastating impacts of severe floods. They can destroy homes and businesses, disrupt transport links leaving people isolated, overload sewage and drainage systems leading to spills and the spread of diseases, and ultimately, cause deaths. The aftermath can be equally harmful: power cuts, lack of drinking water, and silt and mud areas contaminated with toxic substances, not to mention the economic toll.
The Thames Barrier is an important tool to protect London from tidal flooding and storm surges. It became operational in 1982 and is one of the largest movable flood barriers globally. Since its opening, it’s been closed 208 times – 117 to protect against tidal flooding and 91 to protect against combined tidal-fluvial flooding.
However, there are also simple and natural ways to mitigate flood risks. Nature-based solutions address societal challenges, such as climate change, and human health while protecting the environment and helping us build resilience to extreme weather events. Natural flood management and sustainable urban drainage systems (SuDS) are examples of effective strategies to do so.
At Thames21, we use both methods mentioned above in our projects. Besides enhancing the natural landscape’s ability to cut down water overflow, absorb pollution and improve biodiversity, these also provide blue and green spaces for people to enjoy. Natural flood management techniques include building wetlands and storage ponds, planting trees and reducing soil compacting. Some of the common SuDS are rainwater harvesting with a water butt, rain gardens, swapping hard paving for permeable surfaces, and green roofs.
Beckenham Place Park River Restoration, Chinbrook Meadows Wetlands, and Glassmill Pond are examples of some of our current projects that make use of nature-based solutions.
While these can’t solve the problem, they can play an important role in helping both people and the environment cope with a changing climate.
Header image by Michael Elliott Photography