Objectively identifying spatial variability in bankfull stage

The bankfull flow concept has occupied a prominent role in geomorphological theory about process dynamics in alluvial meandering river systems for decades. As the flow that defines the transition between channel and floodplain and marks the level of incipient flooding, bankfull flow represents an important geomorphic and hydrological threshold. However, most field methods of bankfull identification rely on subjective judgement which can result in varying measurements of the same location. The focus of this study is the development of an innovative, objective method for extracting bankfull elevation data from high resolution LiDAR data at different spatial scales. The capability of this method is demonstrated on three different alluvial lowland meandering rivers to provide a range of scale and geomorphic and hydrologic conditions. Selection criteria are defined to maximize objectivity in identification of bankfull surfaces. Bankfull elevations are extracted at any spacing along the river that the user desires, providing the basis for high-resolution mapping of longitudinal variability and the exploration of geomorphic factors that produce this variability. Two-dimensional hydrodynamic modeling is employed to assess the effects of bankfull variability on inundation patterns. The results of this work demonstrate the considerable variability inherent in the study rivers at large and small scales. The presence of geomorphic features, such as sloughs, secondary channels, and meanders, has been shown by this method to affect bankfull elevation. Modeling results display changing spatial patterns of floodplain inundation with increasing flow. The findings have implications for river management efforts related to the natural configuration of channel banks. Additionally, the results illustrate the role of variability in the hydrological complexity of channel-floodplain connectivity.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Geography

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2020

Author dc:creator

• Lindroth, Evan Morrow

Contributors dc:contributor

• Rhoads, Bruce L

• bankfull
• alluvial rivers
• spatial variability
• rating curves

Statement dc:rights

• Copyright 2019 Evan Lindroth

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/106402

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/106402