Droughts are the most expensive climate disasters as they leave long-term and chronic impacts on the ecosystem, agriculture, and human society. The intensity, frequency, and duration of drought events have increased over the years and are expected to worsen in the future on a regional and planetary/global scale. Nature-based solutions (NBS) such as wetland and floodplain restorations, green infrastructures, rainwater harvesting, etc., are highlighted as effective solutions to cope with the future impacts of these events. While the role of NBS in coping with the impacts of other disasters, such as floods, has been extensively studied, there has been a lack of comprehensive review of NBS targeting drought. The following paper provides a unique critical state-of-the-art literature review of individual drought-related NBS around the world, in Europe, and particularly in Belgium, and assesses the critical differences between the NBS applied globally and in Flanders. An extensive literature review was conducted to systematically analyze NBS, listing the type, the location, the status of the implementation, and the possible recommendations proposed to optimize future NBS applications. Finally, a comparison is made between small- and large-scale applications of NBS. By analyzing all these aspects, especially the level of effectiveness and recommendations, insight was gained into the future potential of NBS and possible improvements. The research indicated a lack of scientific publications, especially in Belgium. Hence, grey literature was also included in the literature review. Only four papers included a quantitative assessment regarding the effectiveness of drought on a global level, all stating a positive impact on groundwater recharge. In contrast, at regional and country levels, the performance of NBS was not quantified. The number of large-scale implementations is low, where landscape- or watershed-scale holistic approaches to drought mitigation are still scarce. Some successfully implemented projects are only very local and have a long realization time, two aspects that limit achieving visible impact at a larger scale. Among the many NBS, wetlands are recognized as highly effective in coping with drought but are still degraded or lost despite their significant restoration potential. A common effectiveness evaluation framework shall be followed, which gives policymakers a clear view of the different NBS investment options. Furthermore, a more collaborative approach is recommended globally, including different stakeholder groups, with specific attention to the local communities. To conclude, future research should increase the evidence base and implementation of drought-mitigating NBS.

Drought impacts are increasingly recognized as interdisciplinary, socially influenced processes often resulting in uneven outcomes across different social groups, rather than as mere hydro-climatic events. Yet, many drought impact studies do not fully integrate the knowledge and perspectives of those who directly experience the impacts of droughts. While knowledge co-creation represents a promising avenue to address this challenge, there still remains an ample margin of improvement in the depth and breadth of transdisciplinary approaches in drought impact studies: most studies either limit co-creation to specific phases of the research process (breadth) or fail to meaningfully incorporate non-academic knowledge within those phases (depth). Drawing from a diverse body of literature on transdisciplinarity in sustainability science, integrated water resources management, socio-hydrology, science and technology studies, and critical water studies, we delineate five key dimensions which can support broader and deeper knowledge co-creation processes in drought impact studies, including (1) setting up a collaborative space, (2) framing the co-modelling process, (3) shaping a shared knowledge of drought, (4) co-selecting and co-developing models to understand drought impacts, and (5) being aware of power biases and knowledge imbalances. Incorporating all five dimensions promotes broader and more comprehensive studies, while exploring each dimension in greater detail enhances their depth. Together, these dimensions provide conceptual guidance for developing transdisciplinary approaches that are more integrated, power-sensitive, inclusive, situated, and reflexive.