Invited perspectives: Reframing Transboundary Flood Vulnerability Through Hydrosocial Systems Thinking: Towards Just and Adaptive Governance

Abstract. Transboundary flood risks are intensifying across South Asia due to climate change, land-use change, and rapid development in shared river basins. Yet, governance responses remain dominated by hydrological control and infrastructure-heavy strategies, overlooking the deeper social, institutional, and political drivers of vulnerability. We define transboundary flood vulnerability as the heightened and unequal exposure of downstream and marginalised communities to flood risk, shaped by systemic governance disconnections between hydrological flows, governance fragmentation, and systemic inequalities across borders. Adopting a hydrosocial systems perspective, we conceptualise the Ganges–Brahmaputra basin as an interdependent socio-environmental system where hazards and vulnerabilities are co-produced through feedback between environmental dynamics and governance structures. Through a critical review of the India–Nepal–Bangladesh floodplain, we examine how the absence of basin-wide agreements, limited data-sharing, and the exclusion of local knowledge reinforce vulnerability and undermine resilience. We argue for a fundamental shift toward governance approaches that embrace hydrosocial connectivity, the dynamic interlinkages between water flows, social relations, and governance processes. This framing enables recognition of how risk and resilience are shaped not just by physical flows but by power, politics, and participation. By centring justice, equity, and collaboration, a hydrosocial approach offers a pathway for rethinking transboundary flood governance beyond borders, beyond hydrology, and toward more coordinated approach with adaptive and inclusive outcomes.