The AquaNbS framework for climate resilience: planning and assessing ecological function of aquatic landscapes at the catchment scale

The Nature-Based Solutions (NbS) framework offers a promising pathway to address societal challenges such as food security, water management, and biodiversity loss, all under accelerating climate change. Aquatic ecosystems are central to addressing these challenges; however, their current implementation remains largely focused on isolated sites, limiting their effectiveness at landscape scales. Here, we address this gap by proposing the Aquatic Nature-based Solutions (AquaNbS) framework, which uses catchments as a biophysically meaningful boundary unit to capture the cumulative effects of hydrologically connected aquatic ecosystems with their surrounding land-use. This enables: (1) representation of connectivity across aquatic ecosystems, supporting planning that captures spatial and temporal variation in biodiversity and ecosystem function; (2) coordination across land-use types, allowing areas with greater implementation potential to support downstream and constrained regions; (3) application of standardized hydrologic indicators to establish baselines and track landscape-scale ecological change; and (4) improved accounting of aquatic carbon transport to better constrain mitigation outcomes. For these reasons, we argue catchments provide the functional basis for aligning aquatic NbS planning, implementation, and monitoring with the landscape-scale processes that govern climate adaptation and mitigation outcomes.