Abstract
This article explores the length scales and statistical characteristics of form roughness along the outer banks of two elongate bends on a large meandering river through investigation of topographic variability of the bank face. The analysis also examines how roughness varies over the vertical height of the banks and when the banks are exposed subaerially and inundated during flood stage. Detailed data on the topography of the outer banks were obtained subaerially using terrestrial LiDAR during low flow conditions and subaqueously using multibeam echo sounding (MBES) during near-bankfull conditions. The contributions of various length scales of topographic irregularity to roughness for subaerial conditions were evaluated for different elevation contours on the bank faces using Hilbert–Huang Transform (HHT) spectral analysis. Statistical characteristics for discrete areas on the bank faces were determined by calculating the root-mean-square of normal distances from a triangulated irregular network (TIN) surface. Results of the HHT analysis show that the characteristics of roughness along bank faces composed primarily of non-cohesive sediment, and eroding into cropland, vary with bank elevation and exhibit a dominant range of roughness length scales (~15–50 m). However, bank faces composed predominantly of cohesive material and carved into a forested floodplain have relatively uniform topographic roughness characteristics over the vertical extent of the bank face and do not exhibit a dominant roughness length scale or range of length scales. Additionally, comparison between local surface roughness for subaerial versus subaqueous conditions shows that roughness decreases considerably when the banks are submerged, most likely because of the removal of vegetation and eradication of small-scale erosional features in non-cohesive bank materials by flow along the bank face. Thus, roughness appears to be linked to the hydraulic conditions affecting the bank, at least relative to conditions that develop when banks are exposed subaerially.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 2024-2037 |
| Number of pages | 14 |
| Journal | Earth Surface Processes and Landforms |
| Volume | 42 |
| Issue number | 13 |
| DOIs | |
| State | Published - Oct 2017 |
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Keywords
- fluvial geomorphology
- meander bank roughness
- multibeam echo sounding
- terrestrial LiDAR
ASJC Scopus subject areas
- Geography, Planning and Development
- Earth-Surface Processes
- Earth and Planetary Sciences (miscellaneous)
Cite this
Length scales and statistical characteristics of outer bank roughness for large elongate meander bends : The influence of bank material properties, floodplain vegetation and flow inundation. / Konsoer, Kory; Rhoads, Bruce L; Best, James Leonard; Langendoen, Eddy; Ursic, Mick; Abad, Jorge; Garcia, Marcelo Horacio.
In: Earth Surface Processes and Landforms, Vol. 42, No. 13, 10.2017, p. 2024-2037.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Length scales and statistical characteristics of outer bank roughness for large elongate meander bends
T2 - The influence of bank material properties, floodplain vegetation and flow inundation
AU - Konsoer, Kory
AU - Rhoads, Bruce L
AU - Best, James Leonard
AU - Langendoen, Eddy
AU - Ursic, Mick
AU - Abad, Jorge
AU - Garcia, Marcelo Horacio
PY - 2017/10
Y1 - 2017/10
N2 - This article explores the length scales and statistical characteristics of form roughness along the outer banks of two elongate bends on a large meandering river through investigation of topographic variability of the bank face. The analysis also examines how roughness varies over the vertical height of the banks and when the banks are exposed subaerially and inundated during flood stage. Detailed data on the topography of the outer banks were obtained subaerially using terrestrial LiDAR during low flow conditions and subaqueously using multibeam echo sounding (MBES) during near-bankfull conditions. The contributions of various length scales of topographic irregularity to roughness for subaerial conditions were evaluated for different elevation contours on the bank faces using Hilbert–Huang Transform (HHT) spectral analysis. Statistical characteristics for discrete areas on the bank faces were determined by calculating the root-mean-square of normal distances from a triangulated irregular network (TIN) surface. Results of the HHT analysis show that the characteristics of roughness along bank faces composed primarily of non-cohesive sediment, and eroding into cropland, vary with bank elevation and exhibit a dominant range of roughness length scales (~15–50 m). However, bank faces composed predominantly of cohesive material and carved into a forested floodplain have relatively uniform topographic roughness characteristics over the vertical extent of the bank face and do not exhibit a dominant roughness length scale or range of length scales. Additionally, comparison between local surface roughness for subaerial versus subaqueous conditions shows that roughness decreases considerably when the banks are submerged, most likely because of the removal of vegetation and eradication of small-scale erosional features in non-cohesive bank materials by flow along the bank face. Thus, roughness appears to be linked to the hydraulic conditions affecting the bank, at least relative to conditions that develop when banks are exposed subaerially.
AB - This article explores the length scales and statistical characteristics of form roughness along the outer banks of two elongate bends on a large meandering river through investigation of topographic variability of the bank face. The analysis also examines how roughness varies over the vertical height of the banks and when the banks are exposed subaerially and inundated during flood stage. Detailed data on the topography of the outer banks were obtained subaerially using terrestrial LiDAR during low flow conditions and subaqueously using multibeam echo sounding (MBES) during near-bankfull conditions. The contributions of various length scales of topographic irregularity to roughness for subaerial conditions were evaluated for different elevation contours on the bank faces using Hilbert–Huang Transform (HHT) spectral analysis. Statistical characteristics for discrete areas on the bank faces were determined by calculating the root-mean-square of normal distances from a triangulated irregular network (TIN) surface. Results of the HHT analysis show that the characteristics of roughness along bank faces composed primarily of non-cohesive sediment, and eroding into cropland, vary with bank elevation and exhibit a dominant range of roughness length scales (~15–50 m). However, bank faces composed predominantly of cohesive material and carved into a forested floodplain have relatively uniform topographic roughness characteristics over the vertical extent of the bank face and do not exhibit a dominant roughness length scale or range of length scales. Additionally, comparison between local surface roughness for subaerial versus subaqueous conditions shows that roughness decreases considerably when the banks are submerged, most likely because of the removal of vegetation and eradication of small-scale erosional features in non-cohesive bank materials by flow along the bank face. Thus, roughness appears to be linked to the hydraulic conditions affecting the bank, at least relative to conditions that develop when banks are exposed subaerially.
KW - fluvial geomorphology
KW - meander bank roughness
KW - multibeam echo sounding
KW - terrestrial LiDAR
UR - http://www.scopus.com/inward/record.url?scp=85020865494&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85020865494&partnerID=8YFLogxK
U2 - 10.1002/esp.4169
DO - 10.1002/esp.4169
M3 - Article
AN - SCOPUS:85020865494
VL - 42
SP - 2024
EP - 2037
JO - Earth Surface Processes and Landforms
JF - Earth Surface Processes and Landforms
SN - 0197-9337
IS - 13
ER -