Restoring natural floodplains

What is a floodplain?

A floodplain is the low-lying land adjacent to a river that is shaped by the continuous interaction between river flow, sediment transport, topography, soils and living organisms. Rather than being static landscapes, floodplains are dynamic systems that evolve through natural flooding and sediment deposition over time.^[1] They form the transition zone between aquatic and terrestrial ecosystems and are among the most productive and biologically diverse landscapes in Europe.^[2],[3]

A defining characteristic of a healthy floodplain is its lateral connectivity with the river. In a naturally functioning system, water, sediment, nutrients and organisms can move freely between the river channel and the surrounding floodplain, supporting the ecological and hydrological processes that sustain both ecosystems.^[4],[1]

Why floodplains matter

Connected floodplains provide a wide range of ecosystem services that benefit both nature and society. During periods of high river discharge, they temporarily store excess water, slowing flood waves and reducing flood levels downstream.^[1] This natural buffering capacity is an important component of sustainable flood risk management.

Floodplains also improve water quality by trapping sediments, retaining nutrients and filtering pollutants before they enter downstream waters.^[4],[1],[5] At the same time, they provide essential habitats for aquatic and riparian species, supporting biodiversity and maintaining ecological connectivity across the landscape.^[1],[4]

Because floodplains combine flood regulation, water purification and biodiversity conservation within the same landscape, they play a key role in building resilient river basins and adapting to climate change.^[2],[4]

How floodplains have been disconnected

Over the past century, many European rivers have been heavily modified to support flood protection, navigation, agriculture and urban development. Levees and dikes, river channelisation and straightening, dams and other flow regulation structures, together with urban expansion and land-use change, have progressively disconnected rivers from their floodplains.^[1] As a result, water, sediment and nutrients can no longer move naturally between the river and its floodplain. This loss of connectivity reduces the floodplain’s capacity to store floodwater, degrades riparian habitats and weakens many of the ecosystem functions on which people and nature depend.^[3],[1] To support land-use planning and reduce flood risks, floodplains are often classified into different hydraulic zones. These classifications help authorities assess flood hazards, guide spatial planning and identify areas where development should be restricted.^[6]

What restoring floodplains means

Floodplain restoration aims to re-establish the natural connection between rivers and their floodplains, allowing ecological and hydrological processes to function again. The objective is not simply to recreate historical conditions, but to restore the natural dynamics that underpin healthy and resilient river systems. Depending on local conditions, restoration measures may include setting back or removing levees and dikes, reconnecting side channels, restoring natural flooding regimes, or implementing nature-based solutions such as Room for the River approaches.^[1] By restoring lateral connectivity, these measures increase natural water storage, improve water quality, enhance biodiversity and strengthen the resilience of river basins to climate change and extreme weather events.^{[1],[4],[5],[7]}

Contribution to EU restoration objectives

The restoration of floodplain functions complements the ambition to restore free-flowing rivers by addressing the connection between rivers and their surrounding landscapes. While the Water Framework Directive recognises the importance of hydromorphological processes, it does not explicitly require the restoration of lateral connectivity between rivers and floodplains when ecological status can be achieved without it. The Nature Restoration Regulation strengthens this aspect by requiring Member States to restore degraded ecosystems and improve the ecological functioning of river-floodplain systems.

The Habitats Directive (92/43/EEC) has played an important role in protecting valuable floodplain habitats, such as alluvial forests and floodplain meadows, mainly within the Natura 2000 network. However, its focus is primarily on designated habitats and species. The Nature Restoration Regulation expands this ambition by requiring restoration efforts beyond protected areas, creating opportunities to restore ecological processes and habitat networks at the landscape scale.

Floodplain restoration is also closely linked to European climate objectives. Under the Land Use, Land Use Change and Forestry (LULUCF) Regulation (EU) 2018/841, amended by EU 2023/839, Member States have commitments to maintain and increase carbon removals from land use. Healthy floodplains, wetlands and floodplain forests can contribute to these goals by storing carbon and maintaining important ecosystem functions. The EU Adaptation Strategy (2021) further highlights the role of natural water retention measures and ecosystem restoration in reducing climate risks, including flood and drought impacts.

For policymakers and practitioners, this creates a strong basis for integrating floodplain restoration with biodiversity conservation, flood risk management and climate adaptation. Measures that restore natural floodplain processes can contribute simultaneously to biodiversity objectives under the Nature Restoration Regulation and Habitats Directive, flood risk reduction under the Floods Directive (2007/60/EC), ecological objectives under the Water Framework Directive, and climate mitigation and adaptation targets under EU climate policy. This integrated approach supports restoration strategies that deliver benefits for ecosystems, climate resilience and society.

Key functions to restore

Successful floodplain restoration focuses on restoring natural hydrological, geomorphological and ecological processes rather than recreating specific habitats. Depending on local conditions and project objectives, practitioners should aim to restore one or more of the five key floodplain functions below.

Comparing the five functions

The five functions

Key guidance documents

Several European guidance documents support the planning and implementation of floodplain restoration projects:

• European Environment Agency (2020) – Floodplains: A Natural System to Preserve and Restore
• Ecoflood Guidelines (Blackwell et al. 2006)
• REFORM – Framework for process-based river restoration
• SER International Principles and Standards for Ecological Restoration
• IUCN Global Standard for Nature-based Solutions
• Natural Water Retention Measures (NWRM) Platform
• SpongeScapes Project
• Dam Removal Europe (for projects involving barrier removal and floodplain reconnection)