In 1953, the dykes broke. One of the biggest disasters the Netherlands has ever suffered. Since then, we managed to set up one of the most extensive flood protection projects in the world. Our feet have been dry ever since. But, the tide may be changing. The Netherlands will get hotter, drier and wetter. According the Climate scenarios from the KNMI we will see more and more extreme rainfall towards 2085. Next to that, in between these extreme events, there will be dry periods. Whether you like this or not, it raises the question: ‘’Are our cities ready for the future?’’
It is not just a future scenario. It is happening already. Extreme showers will happen more frequently and will be heavier. This leads to certain problems. For example, in cities like Leiden, the sewage system isn’t able to cope with the extreme amounts of rain that will fall during short periods of time. This will result in flooding in streets and houses, which leads to lots of damages. Already this has happened in Leiden.
Cities are most vulnerable because of increasing urbanization. This causes problems with increased flash flooding after sudden rain. As areas of vegetation are replaced by concrete, asphalt, or roofed structures, the area loses its ability to absorb rainwater. This rain is instead directed into the city sewage system, often overloading it and causing floods.
Municipalities can take measures to prevent the streets from turning into rivers. Some more natural examples include, more green and wide ditches/ponds in suburbs to allow the ground to take up more water. On the other hand, a more mechanical solution is building surface water drainage systems to relief the sewage systems by transporting rain water to rivers or basins.
The solutions named above may not always be possible. For example, there might not be enough space for creating green areas, which is the case in Noorderkwartier, a district in Leiden. I think especially in those areas it is vital to let the citizens know what problems the council is facing in protecting them. With the right incentives, communities can transform their own neighbourhoods in flood save and sustainable places to live. Below are some solutions people can take to achieve this:
- Green open gardens. Paved gardens direct water straigt into the sewage system. Green gardens on the other hand, absorb water and also look more attractive.
- Installing water butts. Green gardens need water. Instead of tapping fresh water, a more sustainable way is to collect rain water. If all houses in a neighbourhood have one, it might just be enough to take up the first beating of a heavy shower. A more advanced idea is the collection of rainwater in large tanks and use that water in a so called ‘grey water system’ (see picture below).
- Green roofs. This is a more challenging solution. Roofs are large surfaces, which potentially can take up a lot of water if planted with grass. However, roofs must be able to support the weight of them.
Let’s embrace these solutions and turn our paved surroundings into green sustainable neighbourhoods where rain is welcome.