Abstract Nature-based flood defences (NBFD) are receiving considerable attention in the coastal adaptation field. Advocates of NBFD point to their cost-effectiveness, flexibility and the range of co-benefits they produce beside flood risk reduction. However, NBFD are not yet common practice. One reason for this may be found in financial barriers. To date, there has been little attention for financial aspects of NBFD, as the literature has focused on design, effectiveness and socio-economic impact of such projects. We address this gap by analysing the financial attractiveness of real-world NBFD from the perspective of the public actor. We address the following research questions: through which mechanisms can public investments in NBFD projects be leveraged? and ii) what are the enabling conditions for these mechanisms? We find two types of revenue generating mechanisms: value capture, in which the public actor generates revenues from private beneficiaries through taxes; and co-investment, in which the project attracts in-kind or cash contributions from other actors. We illustrate the potential of these leveraging mechanisms in four case studies and find that NBFD can generate significant tax revenues in locations with high demand for certain co-benefits, whereas project size, type, timing and beneficiaries of co-benefits determine the potential for co-investment.

中文翻译：

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基于自然的防洪在沿海适应方面利用公共投资的潜力：来自荷兰、印度尼西亚和格鲁吉亚的案例

摘要 基于自然的洪水防御（NBFD）在海岸适应领域受到了相当大的关注。NBFD 的拥护者指出了它们的成本效益、灵活性以及它们在减少洪水风险之外产生的一系列共同利益。但是，NBFD 还不是普遍的做法。造成这种情况的一个原因可能是财务障碍。迄今为止，几乎没有人关注 NBFD 的财务方面，因为文献主要关注此类项目的设计、有效性和社会经济影响。我们通过从公共参与者的角度分析现实世界 NBFD 的财务吸引力来解决这一差距。我们解决以下研究问题：通过哪些机制可以利用对 NBFD 项目的公共投资？ii) 这些机制的有利条件是什么？我们发现了两种类型的创收机制：价值获取，其中公共行为者通过税收从私人受益人那里获得收入；和共同投资，其中项目吸引其他参与者的实物或现金捐助。我们在四个案例研究中说明了这些杠杆机制的潜力，并发现 NBFD 可以在对某些共同利益有很高需求的地方产生可观的税收，而项目规模、类型、时间和共同利益的受益人决定了共同利益的潜力。 -投资。其中项目吸引了其他参与者的实物或现金捐助。我们在四个案例研究中说明了这些杠杆机制的潜力，并发现 NBFD 可以在对某些共同利益有很高需求的地方产生可观的税收，而项目规模、类型、时间和共同利益的受益人决定了共同利益的潜力。 -投资。其中项目吸引了其他参与者的实物或现金捐助。我们在四个案例研究中说明了这些杠杆机制的潜力，并发现 NBFD 可以在对某些共同利益有很高需求的地方产生可观的税收，而项目规模、类型、时间和共同利益的受益人决定了共同利益的潜力。 -投资。