Wednesday, 12 February 2014

Can bioswales stop flooding in the UK?

The flooding in Somerset and the south of England  has highlighted the need for a determined overhaul of the UK's management of flood waters.

Clearly the priority in many of the worst hit areas is to look at the maintenance of existing watercourses and how the catchment area is used further upstream.

But to effectively limit the effects of flooding a much wider view has to be taken with many different factors being taken into account.

One of these must be the role green infrastructure can play; in particular Sustainable Drainage Systems, or SUDS.

Many of our villages, towns and cities are expanding rapidly and as they do so areas which were once fields and shrub-land are coated in impenetrable concrete.

This means any rain that falls is quickly diverted, through guttering and drainage systems, into our water courses and rivers in one great flush.

The rainwater is never allowed to soak slowly down into the soil to join the existing watertable, as it did before the development, which would result in a more gradual and less extreme rising of nearby river levels.

The problem is becoming exacerbated with the ever diminishing size of gardens and green spaces; while the strain placed on overloaded existing drainage systems can cause localised flooding around drain covers.

One solution could be bioswales.

Bioswales are a form of Sustainable Drainage System (SUDS), which can be relatively small and incorporated neatly into an urban environment.

Bioswales  (sometimes referred to as a type of rain garden) are areas which can be built around drains on the sides of roads which allow water to soak down into the ground - preventing the rush of flood waters gushing into rivers.

The transpiration of specially selected plants grown in them to further help divert water away from drainage systems.

The existing drain still works in the usual way if needed, during heavy rain or storms, but when combined with the 'soakaway' abilities of the bioswale there is less of a risk of either the localised pooling or the large-scale flooding you often get from standalone drains.

Bioswales do not even need to take up much room; they can be the same size as many of the grass banks we currently have on our pavements - they just need to be constructed a little differently.

Bioswales can also help remove some of the pollutants in water runoff from our roads and pavements.

And of course, bioswales look good and add some much needed greenery and biodiversity to our urban areas.

The more research I do on bioswales as a wetland scientist the stronger I feel that they should become an integral part of not just any new housing and commercial development, but also our wider flood management plan.

Thankfully there is a push for Sustainable Drainage Systems (SUDS) to be used more extensively in the UK and I think the recent flooding will highlight this need even more.

Bioswales and SUDS are certainly an interesting topic for the MSc in Wetland Science and Conservation.