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Self-adjustment in rivers: Evidence for least action as the primary control of alluvial-channel form and process
Nanson, Gerald C.1; Huang, He Qing2
2017-03-30
Source PublicationEARTH SURFACE PROCESSES AND LANDFORMS
ISSN0197-9337
Volume42Issue:4Pages:575-594
Corresponding AuthorNanson, Gerald C.(gnanson@uow.edu.au)
AbstractLeast action principle (LAP) in rivers is demonstrated by maximum flow efficiency (MFE) and is the foundation of variational mechanics based on energy and work rather than Newtonian force and momentum. Empirical evidence shows it to be the primary control for the adjustment of alluvial channels. Because most rivers flow with imposed water and sediment loads down valley gradients they have largely inherited, they self-regulate energy expenditure to match the work they are required to do to remain stable. Overpowered systems develop a variety of channel patterns to expend excess energy and remain stable. Australia offers an opportunity to study low-energy rivers closely adjusted to very low continental gradients. The anabranching Marshall and single-thread Plenty Rivers flow down nearly straight channels with average H numbers [ratio between excess bed shear and width/depth (W/D) ratio] close to the optimum of 0.3 for stationary equilibrium. Ridge-form divisions of the original channel width create anabranches that radically alter W/D ratios relative to bed shear, the same being true for short-wide islands on the large low-gradient Yangtze River in China. In contrast, Mount Chambers Creek in Australia's tectonically more active Flinders Ranges is accreting an alluvial fan with unstable distributary channels exhibiting H numbers well below the optimum. LAP also explains profound biases in Earth's stratigraphic record. Because meandering is an energy-shedding mechanism, sinuous rivers sequester relatively little sediment resulting in all sequences being just a few tens of metres thick. In contrast, low-energy braided disequilibrium systems can sequester sediment piles over a kilometre in thickness and tens of kilometres wide. LAP provides a new paradigm for river research by identifying the attractor state controlling river channel evolution. It links advances in theoretical physics to fluvial geomorphology, stratigraphy and hydraulic engineering and opens opportunities for diverse investigations in Earth system science. Copyright (C) 2016 John Wiley & Sons, Ltd.
Keywordleast action principle H number self-adjusting rivers alluvial sequestration Earth system science
DOI10.1002/esp.3999
WOS KeywordARID CENTRAL AUSTRALIA ; DISTRIBUTIVE FLUVIAL SYSTEMS ; HYDRAULIC GEOMETRY ; NORTHERN PLAINS ; YANGTZE-RIVER ; ANABRANCHING CHANNELS ; RIPARIAN VEGETATION ; EQUILIBRIUM STATES ; BED STREAMS ; POINT BARS
Indexed BySCI
Language英语
Funding ProjectAustralian Research Council[A00103535] ; Australian Research Council[DP1096911] ; Australian Research Council[DP130104023] ; National Natural Science Foundation of China[41330751] ; National Natural Science Foundation of China[41561144012]
Funding OrganizationAustralian Research Council ; National Natural Science Foundation of China
WOS Research AreaPhysical Geography ; Geology
WOS SubjectGeography, Physical ; Geosciences, Multidisciplinary
WOS IDWOS:000396740300002
PublisherWILEY
Citation statistics
Cited Times:12[WOS]   [WOS Record]     [Related Records in WOS]
Document Type期刊论文
Identifierhttp://ir.igsnrr.ac.cn/handle/311030/64702
Collection中国科学院地理科学与资源研究所
Corresponding AuthorNanson, Gerald C.
Affiliation1.Univ Wollongong, Sch Earth & Environm Sci, Wollongong, NSW, Australia
2.Chinese Acad Sci, Inst Geog Sci & Nat Resources Res, Key Lab Water Cycle & Related Land Surface Proc, Beijing, Peoples R China
Recommended Citation
GB/T 7714
Nanson, Gerald C.,Huang, He Qing. Self-adjustment in rivers: Evidence for least action as the primary control of alluvial-channel form and process[J]. EARTH SURFACE PROCESSES AND LANDFORMS,2017,42(4):575-594.
APA Nanson, Gerald C.,&Huang, He Qing.(2017).Self-adjustment in rivers: Evidence for least action as the primary control of alluvial-channel form and process.EARTH SURFACE PROCESSES AND LANDFORMS,42(4),575-594.
MLA Nanson, Gerald C.,et al."Self-adjustment in rivers: Evidence for least action as the primary control of alluvial-channel form and process".EARTH SURFACE PROCESSES AND LANDFORMS 42.4(2017):575-594.
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