Climate change: Impact of land management on flood risk ignored for too long – How Natural flood management and using land more intelligently will limit flood damage
In an Expert Focus article on Waterbriefing, Daniel Johns, head of adaptation at the Committee on Climate Change explores how natural flood management and using land more intelligently will limit flood damage. Daniel Johns: Over centuries our communities have developed around rivers, to ensure easy access to water for use by populations, industry and for navigation. At the same time, landowners have straightened and dredged rivers, drained their land and removed natural features, aiming to raise agricultural output and get excess water away downstream as quickly as possible. But, in recent years, we have seen time and again the enormous cost of too much water at once flowing into our heavily populated floodplains, despite the billions spent by the government on flood defences.
Only last winter, storms Desmond, Eva and Frank caused damages estimated at £5 billion. Recently constructed flood defences were overwhelmed, such as those in Carlisle, as record rainfall came rushing off the hills. Herein lies part of the problem, but also part of the solution. The way we currently manage the land creates greater flood risk for communities. As the climate continues to warm, and the effects in terms of rainfall become ever clearer, it won’t be acceptable nor affordable in many cases to build higher and higher defences. Alongside continuing to invest in improved structures where we can, we need to harness the land to better deal with the flood water: to slow down and manage flood flows so that the defences can do the job they were built for.
Can storm water management and planning be the answer to preventing flooding in the UK?
In an Expert Focus article for Waterbriefing, Jeremy Jones, Associate Director, Technical Authority for Storm Water Management and Planning, Atkins discusses whether storm water management and planning can provide the answer to preventing flooding in the UK.
Jeremy Jones: With the disruption that storm Angus left behind last week, it provokes the question – are we doing enough to prevent flooding and tackling it at source? Last week during the height of the storm, we had 103 flood alerts in place; a high of 2 inches of rain in Exeter; and flooded properties and roads in Devon. And our weather conditions are showing no sign of changing. Rainfall has increased across all regions of the UK over the last 50 years – winters are wetter and even with drier summers, rainfall is becoming concentrated into more intensive downpours (up 5% in the last 20 years). Traditional methods of removing rainwater – i.e. removing it as quickly as possible from our roads and pavements through the network and out to sea – are not always fit for purpose during periods of severe rainfall. Climate change, urban creep and new developments have together meant that the infrastructure is no longer adequate. So after each period of heavy rain as technical experts we continue to bang the drum that more preventative action should be taken instead of last minute urgent care.
SuDS not only employed in new developments but also as a retrofit opportunity for water companies
Attention then has to turn to Storm Water Management (SWM) and sustainable urban drainage systems (SuDS). SuDS mimic natural processes enabling natural drainage around buildings and other developments which work by slowly draining, or sometimes holding in surplus water caused by rain and surface water. We are now seeing SuDS not only employed in new developments but also as a retrofit opportunity for water companies, with many water companies now grasping the opportunity and developing processes, governance procedures and implementing new measures for SWM.
At Atkins we are advisors to the majority of UK water companies. In addition to assisting them with new ways of working for SWM, we have created the SuDS Studio toolkit which is a unique geospatial tool that brings together our experience in planning and engineering with cutting edge geospatial modelling capabilities. It works by rapidly mapping out potential areas which could benefit from the implementation of SuDS. As a rapid scanning tool, it is a much more cost effective tool than the traditional approach of assessing each area individually. It also prioritises the opportunities for SuDS, which is extremely helpful to the end user.
SuDS can typically cost less than half of what traditional drainage systems cost
As experts working with SuDS on a daily basis, we continue to praise the benefits. SuDS can typically cost less than half of what traditional drainage systems cost, and they can cost much less than retrospective flood defences (even though these will remain an essential part of the flooding protection mix).
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