• Question: What is the best environmentally friendly way to protect against flooding and how practical is it?

    Asked by anon-253939 to Sylvia, Josh, Daire on 20 May 2020.
    • Photo: Josh Wolstenholme

      Josh Wolstenholme answered on 20 May 2020:

      Improving soil health is a good way to start. Soil that is in poor health is compacted or has poor structure, and therefore can’t store as much water as a healthy soil can. This is often due to farming practices and driving heavy machinery over the soil. Doing this reduces the amount of cavities present in the soil that can store water, so when the soil is waterlogged, any excess water becomes surface runoff, eroding the soil and concentrating in streams. If we can better store the water, we can reduce the volume going into streams all at one time, slowing the flow and reducing the likelihood of flood risk.

      As for how practical? I think it depends on how much it would cost to the farmer and how much the government might be able to contribute in terms of funding.

Comments

  • Photo: Kirsty

    Kirsty commented on :

    It’s not my area of research, but I have been to a few talks that explained that one problem in cities now is that so much of the ground is concrete (where water can’t soak in) rather than soil (where the water can gradually soak in). I’d love to see this idea incorporated into town planning – green areas are thought of as nice for leisure, but really they provide so many services too, like helping to prevent flooding!

  • Photo: Sophie

    Sophie commented on :

    Hi Tess!

    I work as a Flood Risk Engineer at a large Engineering company. I design flood risk solutions to protect people, properties and infrastructure (i.e. roads and railways).

    The best way, in my opinion, to protect against flooding is to not build new development in the flood plain! This mapping shows the flood zones in the UK: https://flood-map-for-planning.service.gov.uk/

    Now-a-days, there is lots of policy and legislation which makes it much hard to build in the flood plain. However, there are lots of properties and infrastructure already built in the flood plain, and with climate change, the flood plains are increasing.

    As a result, we try and build sustainable urban drainage systems i.e. attenuation basins, geocellular storage etc to deal with surface water (rainfall). If possible, we infiltrate flood water into the ground using this systems. If that is not an option, then water is discharged either into a river/ sea or sewer (in that order). Sewers are least preferable as lots of them are already near or at capacity in the UK.

    To ensure that we don’t increase flood risk, we design all flood solutions for the 1 in 100 year rainfall event, and include an allowance for climate change (normally a 40% increase on rainfall). This is a pretty good solution but obviously, if a larger flood occurred, there might still be some flooding but there are normally contingency plans in place.

    River flooding is more difficult and tends to cause some of the bigger floods – depending on the number of properties affected, we might design bespoke flood defences. But for single properties, we can design property level protection for example, installing a flood gate on all doors.

    Hope this helps!