Nature and Nurture: How to manage floods

Flood management and prevention has been a controversial, yet key subject of discussion in recent months. A strategy to avoid a repeat of this winter is being examined by scientists, land owners, policy-makers and land-management experts. At last week’s biodiversity APPG meeting, six speakers – scientists and land management professionals – came together to discuss how we should tackle extensive natural and anthropological damage caused by extreme floods.

Speaking in Westminster were Dr. Tim Pagella (Bangor University), Dr. Iwan Jones (Queen Mary University, London), Charles Cowap (Harper Adams University), Martin Ross (Chair, Rivers Trust), Prof. Richard Brazier (University of Exeter) and Rob McInnes (Independent wetlands consultant and Head of Wetland Conservation at Wildfowl &Wetlands Trust).

All contributors were in agreement that the mitigation of floods needs be a collaborative effort including land owners, farmers, scientists, land managers and policy makers. By implementing a catchment-based response we can ensure that all stakeholders benefit from and can contribute to responding. This will ensure productive and cohesive solutions that are area-suitable. In addition, as stated by Charles Cowap, land tenures must be taken into account during planning as how we can manage land depends on who owns it.

Furthermore, all emphasised the need to work with ecosystems and natural-methods of flood prevention in order to be successful. There are multiple ways in which flooding damage can be reduced by promoting and enhancing ecosystem services. Tim Pagella discussed the effectiveness of planting trees to prevent flooding. There are several ecological benefits to this aside from water storage such as carbon sequestration, preventing soil erosion, increasing biodiversity and increasing habitat for farmer livestock in winter. Additionally, there are many cultural and health benefits which, according to Tim’s study, farmers found most valuable. In this small scale study, it was found that planting trees up stream could reduce peak flow of water by 30% in sub catchments – a large scale study is now needed. This sentiment was echoed by Iwan Jones, Richard Brazier and Robert McInnes who discussed the success of using natural systems to control flooding and the water system. By protecting water storage systems such as wetlands and grasslands we can ensure that we reduce flooding in winter and have a sustainable water source in summer. Although, McInnes warns that there are many types of wetlands and that to manage and use these correctly we must adjust practice for each and allocate experts accordingly. Additionally, by working with natural systems, we can achieve good results with a lower economic input.

Professor Brazier investigated how 19^th century drainage ditches on farmland affect water quality and flow. He found that man-made drainage systems – that stopped the natural flow of water through bogs and rivers – were increasing floods and reducing the water storage potential of the land. This causes poor water quality (increased flow carries pollutants and sediment), increased water acidity, decreased biodiversity, decreased ecosystem services and less water available for summer months. By strategically blocking ditches  to reduce flow, they observed a 68% reduction in water loss, increased carbon storage, reduced flood damage and an increase in biodiversity. Although this was on a small scale, similar practices may be implemented in comparable landscapes as observed by the WWF collaboration with farmers in Norfolk.

Although extreme flooding can be damaging to ecosystems and human civilisation, it is also an important part of freshwater cycles. Flooding brings new nutrients, encourages habitat heterogeneity, creates habitat for specialists and creates connectivity to permit migration. This is important for species such as salmon. However, by following damaging land management practices that cause severe floods and destructive flood alleviation like dredging we are compromising this system, ourselves and ecosystem services. Therefore, when policy makers make discuss water management, they must also take into account ecologically clever land management to reduce damaging events.

Check out the British Ecological Society’s Ecological Issue on the impact of extreme flooding on freshwater ecosystems here!