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.

A distributed hydrological model (WASIM-ETH) was applied to a meso-scale catchment to investigate natural flood management as a non-structural approach to tackle flooding and climate change. Changes in peak flows were modelled using climate projections (UKCP09) in combination with afforestation-based land use change. Runoff projections showed a significant increase in peak flows from climate change. Afforestation could reduce some of the increased flow, with greatest benefit from coniferous afforestation, especially when replacing lowland farmland. Nevertheless, large-scale woodland expansion was required to maintain peak flows close to present and effects were reduced for more extreme floods. Afforestation was also modelled to increase risks of low flow episodes in summer. Evaluation using land-use scenarios showed catchment-scale trade-offs across multiple objectives were particularly complex when afforestation replaced lowland farmland. Hence, combined structural/non-structural measures may be required here and in similar catchments, with integrated catchment management to synergize across multiple objectives. Naturalflood management, land use and climate change trade-offs: the case 1 of Tarland catchment, Scotland 2 3

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