Contrasting the Middle Paraná and Mississippi Rivers to develop a template for restoring large floodplain river ecosystems

Abstract Effective rehabilitation of large rivers requires a concept of normal floodplain river behavior ‐ the reference condition ‐ to understand system‐level disturbance history and to develop plans to improve river health. However, reference conditions are difficult to obtain for large rivers. Using Correspondence Analysis of a select subset of the world's great rivers, we show that the Paraná and Mississippi Rivers are relatively similar at the watershed scale based on general geographical and physico‐chemical variables, although these rivers differ substantially in disturbance history. We believe that the less disturbed Paraná River provides reference conditions for the more disturbed Mississippi River for some processes and functions whereas the Mississippi River provides a compelling vision of the future state of the Paraná River unless sustainable development plans are developed and implemented. By integrating information between them, this pair of rivers provides a unique opportunity for scientists to develop more robust conceptual models and improved deterministic models to better guide river management and rehabilitation actions. We suggest that development of large river reference conditions may be better obtained through expanded inter‐hemispheric scientific collaboration on multiple systems than through increased focus on a single impacted system.