Scaling Nature-based Solutions for flood resilience: from evidence to investment
May 14, 2026
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As climate risks intensify across Europe, flood management systems are under increasing pressure to evolve. Traditional grey infrastructure, such as dams, dykes, and channelisation, continues to dominate but is proving insufficient in addressing the growing scale and frequency of extreme weather events.
Nature-based Solutions (NbS) are increasingly recognised as a complementary approach. As highlighted in research titled Nature-based Solutions for managing rising flood risk and delivering multiple benefits, “NbS, which use natural or modified ecosystems to manage runoff and floodwaters, can potentially address both challenges, contributing to a diversified portfolio for reducing flood risk while simultaneously promoting the protection or restoration of riverine ecosystems and their social and environmental benefits.”
This growing recognition is reflected in the work of the Global Infrastructure Basel Foundation (GIB) in collaboration with the World Wide Fund for Nature (WWF) on flood resilience in Thessaly, Greece, where NbS are being explored as part of catchment-level flood management strategies. These approaches demonstrate that restoring natural systems, such as floodplains and river corridors, can play a meaningful role in reducing risk.
However, while NbS are increasingly included in policy discussions and European frameworks, they are not yet mainstream in practice. Moving from recognition to implementation remains a key challenge, particularly at larger scales, where greater financial and institutional support is required.
Work led by WWF in Greece offers practical insight into how NbS are being implemented on the ground. Over the past two decades, efforts have evolved from biodiversity-focused conservation to approaches that explicitly link ecosystems with flood risk reduction.
Early initiatives, such as wetland inventories across Mediterranean islands, focused primarily on ecological value. While these projects acknowledged the role of wetlands in mitigating floods, the emphasis was not on public safety. Over time, this narrative has shifted.
Wetlands, rivers, and coastal ecosystems have increasingly been framed as systems that directly contribute to human protection. Coastal wetlands, for example, act as buffer zones that absorb wave energy and protect inland areas, while also maintaining groundwater quality. Similarly, restoring natural water flows can reduce flood risks by allowing water to move more freely through the landscape.
This shift is reflected in practical interventions. In Chania, Crete, the removal of approximately 40,000 cubic metres of debris from a coastal wetland restored its natural drainage function, reducing flood risk in the surrounding area. On islands such as Paros, the construction of small traditional stone check dams in seasonal streams has contributed to both increased biodiversity and improved groundwater recharge.
“If we apply sustainable measures, and not only large-scale works such as dams, we achieve multiple positive impacts in the local context, biodiversity, aquifer recharge.”
Thanos Giannakakis, WWF Greece
Read more about implementations of combined Nature-based Solutions in the Greece
Despite growing evidence of effectiveness, NbS implementation continues to face significant structural barriers. A key issue is the gap between knowledge generation and large-scale execution.
Funding programmes such as Horizon Europe play an important role in supporting research, stakeholder engagement, and early-stage project development. They help build the case for NbS and bring together relevant actors. However, these instruments are not designed to finance full implementation at the scale required to address flood risks across entire catchments.
As a result, many NbS initiatives remain at the level of studies, pilot projects, or monitoring efforts. Scaling them requires substantially larger investments, typically from national governments, regional funding mechanisms, or major financial institutions.
The WWF pre-feasibility study on NbS in Thessaly also emphasises the need to scale up investment and strengthen financial frameworks, including the mobilisation of private capital. Private sector actors, such as insurance companies, have a clear interest in reducing flood-related losses, particularly in rural and agricultural areas. However, pathways for their involvement are not yet well defined.
Another key challenge lies in technical integration. While engineers are well equipped to design conventional infrastructure, NbS lack standardised technical guidance. Translating ecosystem restoration into engineering language, so that it can be designed, costed, and implemented within existing systems, remains a critical gap.
Without addressing these financial, policy, and technical barriers, NbS will continue to be applied in limited contexts rather than becoming a mainstream solution.
Recent flood events in Greece illustrate the scale of the challenge. Extreme weather systems such as the Ianos Medicane (2020) or Daniel and Elias Mericanes (2023) have caused widespread damage, with economic losses estimated to reach up to one billion dollars and more than 5 billions respectively. Reporting from BBC News and scientific assessments indicates that even a single event can result in damages exceeding hundreds of millions.
Despite these recurring impacts, there is still no standardised methodology for quantifying the full economic cost of floods. This limits the ability of governments to plan proactively and prioritise preventive measures.
“If we show governments that every few years we face events of this magnitude and cost, we can begin to consider how to reduce floods by applying measures that are more cost-effective than traditional infrastructure, while also providing additional ecosystem services.”
Thanos Giannakakis, WWF Greece
NbS offers a way to reduce long-term costs by addressing flood risks at their source. Measures such as river restoration, floodplain reconnection, and natural water retention can reduce the need for reactive spending on disaster recovery.
At the same time, these approaches provide additional benefits, including improved biodiversity, enhanced water systems, and more sustainable land use. However, implementing them often requires changes in land use, particularly in areas with agricultural activity. This makes early engagement with local communities essential to ensure feasibility and long-term success.
NbS has demonstrated their potential to reduce flood risk while delivering broader environmental benefits. The challenge now is to move beyond small-scale applications and implement them at the scale required to address systemic risks.
This transition will depend on strengthening financial frameworks, developing clear policy incentives, and integrating NbS into standard engineering and planning practices. It will also require closer collaboration between public institutions, private investors, and local communities.
The evidence is already in place. What remains is the ability to translate that evidence into action at scale.
