The Widths of Rivers and Streams Across Spatial Scales: A Framework for Improving River-Atmosphere Biogeochemical Exchange Estimates

The width of rivers, and how it scales from narrow headwater streams to wide basin outlets, is a key yet highly uncertain parameter in estimating river-atmosphere biogeochemical exchange. This study characterizes the full distribution of river widths across all stream orders in the Mississippi River Basin using multi-source remote sensing, field surveying, and a nested sampling approach. River widths within each stream order consistently follow a log-normal distribution. When integrated with basin-wide river network lengths, these width distributions combine to form an emergent Pareto distribution. Using this newfound width scaling framework for the Mississippi Basin, we estimate a sum river surface area of 17,828 ± 2,563 km², an area broadly consistent with previous evaluations. This study's refined characterization of river widths across scales has wide-ranging applications including a more accurate accounting of river and stream surface area with implications for global river-atmosphere biogeochemical exchange assessments.