From Flow to Gate: Integrating Knowledge in Collaborative Governance of Cross-Border Estuaries—Comparative Insights from the Schelderaad and the Forum Tideelbe

Estuary governance exemplifies the challenge of decision-making under incomplete knowledge, thereby turning knowledge integration into a central practice of governance. Varying across cross-border governance settings, the forms of this integration try to respond to the persistent challenges of governing complex socio-environmental systems characterized by uncertainties and contested stakeholder landscapes. Tracing the pathway ‘from flow to gate’, this paper examines how knowledge integration unfolds within collaborative estuary governance, using a comparative case study of the Schelderaad (Scheldt estuary) and the Forum Tideelbe (Elbe estuary) as illustrative governance regimes. Empirical data were collected through document analysis, media sources, and semi-structured interviews with stakeholders from both examples. This study employs a novel three-phase conceptual lens to systematically assess contextual preconditions, integration processes, and resulting effects of knowledge integration in these settings. The findings highlight that effective knowledge integration depends not solely on technical expertise and institutional arrangements, but also on social dynamics, ultimately shaping the legitimacy and learning capacity of collaborative estuary governance. In this way, the comparative analysis highlights the relevance of context sensitivity, institutional anchoring, and the fundamentally social nature of knowledge integration, which can either foster shared understanding and cross-border learning or reinforce disagreement, mistrust, and conflict.