A restatement of the natural science evidence concerning catchment-based ‘natural’ flood management in the UK

Abstract

Flooding is a very costly natural hazard in the UK and is expected to increase further under future climate change scenarios. Flood defences are commonly deployed to protect communities and property from flooding, but in recent years flood management policy has looked towards solutions that seek to mitigate flood risk at flood-prone sites through targeted interventions throughout the catchment, sometimes using techniques which involve working with natural processes. This paper describes a project to provide a succinct summary of the natural science evidence base concerning the effectiveness of catchment-based ‘natural’ flood management in the UK. The evidence summary is designed to be read by an informed but not technically specialist audience. Each evidence statement is placed into one of four categories describing the nature of the underlying information. The evidence summary forms the appendix to this paper and an annotated bibliography is provided in the electronic supplementary material.

Capturing the multiple benefits associated with nature‐based solutions: Lessons from a natural flood management project in the Cotswolds, UK

“…In most European projects, NBSs are used in combination with more conventional flood risk techniques, such as culverts, flood walls, and engineered dams (Burgess‐Gamble et al, ); the evidence from Stroud suggests that minor flood events have been nullified by the numerous NFM interventions installed across the SF Catchment. The idea that NBS could be utilized as a flood defence mechanism does present some challenges to the traditional cost–benefit framework as much of the evidence regarding the impact of NFM interventions (i.e., LWD) is modelled rather than observed and there is therefore little information on the performance, longevity, and operation and maintenance of such structures (Burgess‐Gamble et al, ; Dadson et al, ) to be able to effectively cost these. In the SF Project, it is generally accepted that LWD will need managing but that the structures can be replaced or reinforced during normal woodland or farm management practices using material on site or nearby.…”

Fragmentation and thresholds in hydrological flow‐based ecosystem services

“…Any flood peak mitigation effects will also be dependent on synchronicity of hydrograph peaks between tributaries (Saghafian and Khosroshahi ), and the scale at which flood risk is a concern (Dadson et al. ). Nonetheless, the LUCI model has shown good performance in validation against observed data for simulated flow and N concentration in streams at the national scale in Wales (see supplementary material in Sharps et al.…”

Mesoscale rainfall patterns observed around wetlands in sub‐Saharan Africa

“…It is estimated that wetland CH 4 emissions represent 20–40% of the global CH 4 budget, making them the largest single natural source of atmospheric CH 4 (Denman et al ., ). Wetlands also provide important benefits for aquatic and terrestrial ecosystems via water quality and elements of natural flood control (Acreman and Holden, ; Dadson et al ., ). In some wetland areas (e.g.…”