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Spatial Variability in Bankfull Stage and Bank Elevations of Lowland Meandering Rivers: Relation to Rating Curves and Channel Planform Characteristics
Author(s) -
Lindroth Evan M.,
Rhoads Bruce L.,
Castillo Cesar R.,
Czuba Jonathan A.,
Güneralp İnci,
Edmonds Doug
Publication year - 2020
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/2020wr027477
Subject(s) - floodplain , hydrology (agriculture) , stage (stratigraphy) , channel (broadcasting) , elevation (ballistics) , geology , alluvium , bank , rating curve , planform , spatial variability , bank erosion , range (aeronautics) , geomorphology , sediment , geography , geometry , geotechnical engineering , statistics , mathematics , cartography , paleontology , materials science , engineering , electrical engineering , composite material , aerospace engineering , aerodynamics
Abstract Mutual adjustment between process and form shapes the morphology of alluvial river channels, including channel banks. The tops of banks define the transition between the channel and adjacent floodplain, which corresponds to the level of incipient flooding. Despite the geomorphological and hydrological importance of this transition, few, if any, studies have extensively examined spatial variability in bank elevations and its influence on bankfull stage. This study uses an objective method to explore this variability at two spatial resolutions along three alluvial lowland meandering rivers. Results show that variability in bankfull stage is inherent to all three rivers. The mean variability of bankfull stage about the average downstream gradient in this stage is 10% to 20% of mean bankfull depth. Elevations of channel banks exhibit similar variability, even after accounting for systematic variations in heights of inner and outer banks associated with river meandering. Two‐dimensional hydraulic simulations show that the elevation range of mean variability in bankfull stage overlaps considerably with the elevation range of high curvature on rating curves, confirming that variability in bankfull stage influences the shape of these curves. The simulations verify that breaks in channel banks allow flow to extend onto the floodplain at stages below the average bankfull stage. The findings provide fundamental insight into the variable nature of bankfull conditions along meandering rivers and the role of this variability in channel‐floodplain connectivity. The results also inform river‐restoration efforts that seek to re‐establish the natural configuration of channel banks.