Evaluating wider benefits of natural flood management strategies: an ecosystem-based adaptation perspective

Abstract

Climate change is projected to alter river flows and the magnitude/frequency characteristics of floods and droughts. Ecosystem-based adaptation highlights the interdependence of human and natural systems, and the potential to buffer the impacts of climate change by maintaining functioning ecosystems that continue to provide multiple societal benefits. Natural flood management (NFM), emphasising the restoration of innate hydrological pathways, provides important regulating services in relation to both runoff rates and water quality and is heralded as a potentially important climate change adaptation strategy. This paper draws together 25 NFM schemes, providing a meta-analysis of hydrological performance along with a wider consideration of their net (dis) benefits. Increasing woodland coverage, whilst positively linked to peak flow reduction (more pronounced for low magnitude events), biodiversity and carbon storage, can adversely impact other provisioning serviceespecially food production. Similarly, reversing historical land drainage operations appears to have mixed impacts on flood alleviation, carbon sequestration and water quality depending on landscape setting and local catchment characteristics. Wetlands and floodplain restoration strategies typically have fewer disbenefits and provide improvements for regulating and supporting services. It is concluded that future NFM proposals should be framed as ecosystem-based assessments, with trade-offs considered on a case-by-case basis.

Challenges for mainstreaming Ecosystem-based Adaptation into the international climate agenda

“…In fact, vulnerability assessments are the foundation for any EbA strategy and are fundamental instruments to understand where climate change will have impacts and which ecosystems are more susceptible to change [45]. EbA recognizes the uncertain future expected under climate change, and that the most effective strategies to reduce risk are in the line of improving the systems resilience rather than focusing on a particular outcome [46]. Long-term adaptation strategies would enhance social and ecological resilience even without specific information on the future climate conditions of a target ecosystem [7].…”

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

“…As a consequence of major flood events, climate change adaptation, and societal pressure, a sustainable flood management approach emerged as a ‘philosophy which prioritises risk reduction through a range of measures that can include structural measures, but are more economically and environmentally sustainable than relying on structural measures alone’ (Waylen, Holstead, Colley, & Hopkins, , p. S1078). According to Waylen, Holstead, Colley, and Hopkins (), this new approach includes NFM alongside related terms, such as ‘Making space for the river,’ ‘Working with Natural Processes,’ ‘Working with Nature,’ ‘Ecosystem‐based Flood Risk Management,’ or ‘Engineering with Nature.’ NFM may involve altering multiple elements of a catchment water balance by promoting interception, infiltration, and groundwater storage, enhancing water losses through evapotranspiration, lengthening hydrological pathways, and increasing flow resistance (Forbes, Ball, & McLay, ; Iacob, Rowan, Brown, & Ellis, ).…”

Realising the potential of natural water retention measures in catchment flood management: trade‐offs and matching interests

“…Afforestation is known to have multiple effects on catchment hydrology, including increased infiltration and reduced runoff due to higher rates of evapotranspiration (Neary et al ., ). Afforestation can also reduce flood peaks (Iacob et al ., ) and may support precipitation recycling where water returned to the atmosphere falls as rain in downwind areas (Ellison et al ., ). SRF where willow or other fast‐growing tree species are grown for bioenergy production has been evaluated in Sweden (Lindroth and Båth, ) and elsewhere in the Baltic Sea basin (Mola‐Yudego, ).…”