Entropy and optimality in river deltas
The form and function of river deltas is intricately linked to the evolving structure of their channel networks, which controls how effectively deltas are nourished with sediments and nutrients. Understanding the coevolution of deltaic channels and their flux organization is crucial for guiding main...
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Published in | Proceedings of the National Academy of Sciences - PNAS Vol. 114; no. 44; pp. 11651 - 11656 |
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Main Authors | , , , , , , |
Format | Journal Article |
Language | English |
Published |
United States
National Academy of Sciences
31.10.2017
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Subjects | |
Online Access | Get full text |
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Summary: | The form and function of river deltas is intricately linked to the evolving structure of their channel networks, which controls how effectively deltas are nourished with sediments and nutrients. Understanding the coevolution of deltaic channels and their flux organization is crucial for guiding maintenance strategies of these highly stressed systems from a range of anthropogenic activities. To date, however, a unified theory explaining how deltas self-organize to distribute water and sediment up to the shoreline remains elusive. Here, we provide evidence for an optimality principle underlying the self-organized partition of fluxes in delta channel networks. By introducing a suitable nonlocal entropy rate (nER) and by analyzing field and simulated deltas, we suggest that delta networks achieve configurations that maximize the diversity of water and sediment flux delivery to the shoreline. We thus suggest that prograding deltas attain dynamically accessible optima of flux distributions on their channel network topologies, thus effectively decoupling evolutionary time scales of geomorphology and hydrology. When interpreted in terms of delta resilience, high nER configurations reflect an increased ability to withstand perturbations. However, the distributive mechanism responsible for both diversifying flux delivery to the shoreline and dampening possible perturbations might lead to catastrophic events when those perturbations exceed certain intensity thresholds. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 Author contributions: A.T., A.L., D.A.E., I.Z., T.T.G., A.R., and E.F.-G. designed research, performed research, analyzed data, and wrote the paper. Reviewers: A.K., Max Planck Institute for Biogeochemistry; and J.B.S., University of Arkansas. Contributed by Andrea Rinaldo, August 29, 2017 (sent for review May 22, 2017; reviewed by Axel Kleidon and John B. Shaw) |
ISSN: | 0027-8424 1091-6490 |
DOI: | 10.1073/pnas.1708404114 |