What does co-creation of knowledge look like in water sciences?  

Co-creation is increasingly promoted within hydrological research as a way to address complex and contested water challenges, yet its meaning, scope, and implementation are necessarily highly variable in practice due to the specifics of local contexts and goals. Within the framework of the IAHS HELPING (Hydrology Engaging Local People IN one Global world) decade and as part of the Co-Creation of Water Knowledge working group (CCWK), we conducted a systematic review of co-creation in water-related research to examine how collaborative knowledge production is conceptualized, operationalized, and evaluated across the hydrological research lifecycle. We focus explicitly on co-creation processes that involve empowering or co-leading of societal engagement, excluding one-way consultation or extractive participation.Following a structured multi-stage screening of 3,971 publications retrieved from Web of Science and Scopus, we identified and analysed 144 case studies that met stringent co-creation criteria. The review was guided by a qualitative screening framework developed within the CCWK working group and structured around four core elements of co-creation—relationship building, leadership, tools and techniques, and knowledge inclusion—together with four overarching principles: inclusivity, openness, legitimacy, and actionability (Castelli et al., 2025).We observed a rapid increase in co-creation approaches in hydrology after 2013, concentrated in Europe and North America. Rivers, urban water systems, and watershed management were the most frequent focus of co-creation. Most processes were initiated by researchers, in contrast to community- or government-led initiatives. While collaborative and facilitative leadership was frequently reported, genuine redistribution of decision-making power was rare and/or poorly documented.Recurring bundles of tools rather than single techniques were used for co-creation, most commonly workshops, interviews, participatory mapping, modelling, and scenario-based approaches. Scientific and governance knowledge overwhelmingly dominated, in contrast to Indigenous and traditional knowledge systems. Although most studies claim actionable outcomes, concrete evidence of implementation, long-term impact, or environmental change was uneven, and evaluation frameworks were scant.Overall, our review shows that co-creation in water science is widely invoked but inconsistently defined, implemented, and assessed. We identify recurring structural barriers related to funding architectures, institutional constraints, power asymmetries, and short project timeframes. By synthesising empirical patterns across cases, this study clarifies where and how co-creation contributes meaningfully to addressing wicked water problems, and where its application risks becoming rhetorical rather than transformative. This review lays the work for our future work developing a vision for what co-creation of water knowledge should become in the next decade and how we can get there.This work was performed as part of the IAHS HELPING Working Group on “Co-Creating Water Knowledge”: https://iahs.info/Initiatives/Scientific-Decades/helping-working-groups/co-creating-water-knowledge/ References: Castelli, G., Howard, B. C., Adyel, T. M., AghaKouchak, A., Agramont, A., Aksoy, H., … Ceperley, N. (2025). Co-creating water knowledge: a community perspective. Hydrological Sciences Journal, 70(16), 2899–2919. https://doi.org/10.1080/02626667.2025.2571065