Deltas Retain 28% of Global River Sediment, the Rest Enters the Ocean

Credit: USGS, Unsplash Editors’ Highlights are summaries of recent papers by AGU’s journal editors. Source: AGU Advances Deltas cover vast areas, including many where humans live. While it is widely known that deltas are defined as where river sands and mud are deposited along coastlines, it remains uncertain how much sediment sticks around on deltas compared to how much ends up in the ocean. Deltas are also diverse in shape and how they are formed, making this question harder to crack. Nienhuis et al. [2026] apply a model to more than 1,700 deltas around the world and find that about 30% of all river sand and mud builds delta plains. The authors note that this is enough to fill the Empire State Building with sediment every two hours. This number shows how much land these deltas are building, which is important for understanding how much deltas will be able to keep up with sea level rise and subsidence. Citation: Nienhuis, J. H., Paniagua-Arroyave, J. F., Dunn, F. E., Cohen, S., & Törnqvist, T. E. (2026). Global river sediment retention on delta plains. AGU Advances, 7, e2026AV002503. https://doi.org/10.1029/2026AV002503 —M. Bayani Cardenas, Editor, AGU Advances Text © 2026. The authors. CC BY-NC-ND 3.0Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.