Abstract Nature-based measures (NBMs), understood here as measures such as floodplain restoration that use ecosystem processes to meet societal challenges, are increasingly advocated as promising solutions for managing flood risks. A suitable instrument to implement NBMs are flood risk management plans (FRMPs) stipulated by the EU Floods Directive. While prior research suggests several governance challenges for NBM uptake in FRMPs, little is known so far regarding the actual extent of NBM uptake and its role in decision-making of flood risk management. Germany, with a coherent water policy framework but state-specific implementation conditions, provides a suitable case study for exploring the decision-making practices that are used in the planning process for FRMPs by German federal states with different water governance characteristics. The aim of this study is to analyze the actual uptake of NBMs in German FRMPs, and to explore potential factors of the FRMP preparation and decision-making practices explaining this uptake. Our explorative research design is based on a document analysis method which assesses the contents of FRMPs of three German federal states. The results offer the first empirical evidence of the uptake of NBMs in Germany and insights into how NBMs and other measure types are chosen for FRMPs. Our findings confirm an overall low uptake of NBMs, with diverging preferences for particular NBM types between the three states. Looking across the states, the level of NBM uptake is likely to be higher if rivers with higher stream order are considered in the FRMP's spatial scope, the potential flood risk in a river basin is low, and positive flood impacts and positive cost-benefit ratios are expected. We conclude that FRMPs still hold substantial potential to enhance the NBM uptake in flood risk management planning. To make use of this potential, we suggest three key strategies to increase the change for a better NBM uptake including applying FRMPs at different spatial levels and degrees of details.

中文翻译：

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探索在洪水风险管理中采用基于自然的措施：来自德国联邦各州的证据

摘要 基于自然的措施 (NBMs)，这里被理解为诸如利用生态系统过程来应对社会挑战的洪泛区恢复等措施，越来越被认为是管理洪水风险的有希望的解决方案。实施 NBM 的合适工具是欧盟洪水指令规定的洪水风险管理计划 (FRMP)。虽然先前的研究表明在 FRMP 中采用 NBM 面临一些治理挑战，但到目前为止，对于 NBM 的实际采用程度及其在洪水风险管理决策中的作用知之甚少。德国具有连贯的水政策框架和特定于州的实施条件，为探索具有不同水治理特征的德国联邦州在 FRMP 规划过程中使用的决策实践提供了合适的案例研究。本研究的目的是分析德国 FRMP 中 NBM 的实际吸收情况，并探索解释这种吸收的 FRMP 准备和决策实践的潜在因素。我们的探索性研究设计基于评估德国三个联邦州 FRMP 内容的文件分析方法。结果提供了德国采用 NBM 的第一个经验证据，并深入了解了如何为 FRMP 选择 NBM 和其他措施类型。我们的研究结果证实了 NBM 的总体低吸收率，三个州之间对特定 NBM 类型的偏好不同。纵观各州，如果在 FRMP 的空间范围内考虑河流秩序较高的河流，则 NBM 的吸收水平可能会更高，流域的潜在洪水风险较低，预计会产生积极的洪水影响和积极的成本效益比。我们得出的结论是，FRMP 仍然具有在洪水风险管理规划中提高 NBM 吸收的巨大潜力。为了利用这种潜力，我们提出了三个关键策略来增加改变以获得更好的 NBM 吸收，包括在不同的空间水平和细节程度上应用 FRMP。