Planning for Flooding – Natural Flood Defences and Biodiversity

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Last week I attended the All Party Parliamentary Group on Biodiversity. The topic was “Natural Flood Defences – what works, who pays and can biodiversity benefit too?” Panel speakers included the Director of Natural England, the Government environmental advisory body, and others from industry, NGOs and academia.

You’d have had to have been living in a black hole to have missed the recent flooding in Cumbria, which hit some communities not once but twice! We are told that the total estimate of cost due to the 2015 winter floods was around £5.5bn to the UK’s insurance sector, businesses, individuals, communities and Government. While Government has pledged to spend £2.3bn on flood defences in this Parliament, the concern is that new and innovative ways need to be found to stem the flows.

Natural flood defences can be used alongside more traditional measures (floodwalls, embankments etc.) to provide some mitigation for smaller catchments. Such natural measures include soil improvement and porous surfacing to increase infiltration, slowing flows (e.g. contour planning and woody debris dams) and storing floodwaters (e.g. floodplain reconnection and retention ponds and bund).

Is there a role for planning in all this?

As is so often the case at the moment, talk focussed on the Housing and Planning Bill which will be entering the Committee Stage at the House of Lords on 8 March. 

There have been calls from some quarters for the Bill to introduce a statutory “duty of resilience” on developers to mitigate and account for the costs of the impacts of development on sewerage systems and wetlands. It is difficult to see how this goes any further than the current position. Most planning permissions for large-scale residential or mixed developments are conditional upon drainage and flood programmes being approved by the local planning authority prior to commencement of development to manage the risk of flooding. If there are potential impacts on protected wetlands, these should also be addressed through condition. The importance placed on these types of conditions is highlighted by Parliament’s decision to exclude them from the deemed discharge provisions introduced in April 2015 to deal with delays.

Although many developments coming through do incorporate natural flood defences it would be good to see more incorporated into design.  However, this needs to be incentivised – the carrot as opposed to the stick approach. Placing a heavier burden on developers is only going to slow development further. There also needs to be a better body of evidence supporting the efficacy of such measures. Neighbourhood planning is one way that people concerned about flooding in their local area can use their local knowledge as to where natural culverts and watercourses lie to influence development design.

As to whether biodiversity can benefit too, the huge storage capacity of wetlands means we are more resilient to floods, but wetlands must be properly managed for nature to thrive. We heard from Rewilding Britain that a licensed beaver re-introduction in Devon could be having a positive effect on flooding there. Beavers are well-known for their natural woody dam-making tendencies. Whether or not such a measure would have the desired effect from a flooding perspective remains to be seen - beaver dams can of course cause floods themselves - and Natural England are yet to comment as to whether or not this re-introduction is to be repeated across the country. Beavers would add a true element of uncertainty, they can bring down trees which can damage infrastructure and buildings, and certainly aren’t likely to abide by a TPO. But, planning aside, it would be nice to see these little chaps scampering around the British countryside again!