Introduction: The Mississippi River Basin—a model for studying the Anthropocene in situ

Is it possible to trace ongoing transitions in the Earth system back to the regional scales at which they are produced and where their effects can be directly experienced? This editorial introduces two special issues of The Anthropocene Review that document a two-year, transdisciplinary experiment: a collaborative investigation of the Mississippi River Basin (MRB) as a model region for studying the Anthropocene condition in situ. Coordinated by the Anthropocene Curriculum, an initiative led by the Haus der Kulturen der Welt and the Max Planck Institute for the History of Science,1 the project Mississippi: An Anthropocene River involved a large consortium of institutions and more than three hundred researchers, artists, activists, and local community members. Together, participants learned about, questioned, and experienced the Anthropocene at a level meaningful to people, a level at which historical legacies and future commitments play out amid concrete infrastructures and socio-ecological formations, and alongside existing inequalities and life’s everyday struggles. The introduction summarizes eleven scientific and creative research outputs that were selected from this wide-ranging experiment, contextualizes the river’s history, and explains the regional approach the project undertook.

Leveraging River Network Topology and Regionalization to Expand SWOT-Derived River Discharge Time Series in the Mississippi River Basin

The upcoming Surface Water and Ocean Topography (SWOT) mission will measure rivers wider than 50–100 m using a 21-day orbit, providing river reach derived discharges that can inform applications like flood forecasting and large-scale hydrologic modelling. However, these discharges will not be uniform in time or coincident with those of neighboring reaches. It is often assumed discharge upstream and downstream of a river location are highly correlated in natural conditions and can be transferred using a scaling factor like the drainage area ratio between locations. Here, the applicability of the drainage area ratio method to integrate, in space and time, SWOT-derived discharges throughout the observable river network of the Mississippi River basin is assessed. In some cases, area ratios ranging from 0.01 to 100 can be used, but cumulative urban area and/or the number of dams/reservoirs between locations decrease the method’s applicability. Though the mean number of SWOT observations for a given reach increases by 83% and the number of peak events captured increases by 100%, expanded SWOT sampled time series distributions often underperform compared to the original SWOT sampled time series for significance tests and quantile results. Alternate expansion methods may be more viable for future work.