Dissertation/Thesis Abstract

Derivation and Application of Idealized Flow Conditions in River Network Simulation
by Afshari Tork, Shahabeddin, Ph.D., The City College of New York, 2018, 216; 13422984
Abstract (Summary)

Streamflow information is essential for many important uses across a broad range of scales, including global water balances, engineering design, flood forecasting, reservoir operations, navigation, water supply, recreation, and environmental management.

Natural streams are characterized by changes in cross-section geometry, slope, and geophysical properties (bed-roughness, channel slope, etc.) along their reaches. Variations in the shape and size of the channel bed geometry result from several interacting features of the river system including the effect of different flow regimes, slope, sediment load, etc. Simplifying the river bed geometries could reduce the burden of assembling the required data, so implementing less detailed routing procedures could lower the computational burden. “At-a-station” hydraulic geometry (AHG) relationships are power-law functions which relate river discharge to key the hydraulics (i.e., velocity, depth, width, and flow area). The AHG relations have been introduced and discussed among researchers, engineers, and geomorphologist since the '50s based upon a limited number of observations made over few flow monitoring stations across the United States.

This doctoral thesis starts with an introduction to statistical data filtering procedures that are being trained and tested over both synthetic and realistic data followed by being applied over ~4000 U.S. Geological Survey’s river monitoring stations to compute AHG parameters based upon robust discharge-hydraulic measures. Given “refined” dataset, estimated AHG parameters are combined with morphological (channel pattern, channel slope, etc.) and geophysical features at a site. Doing so, potential interrelation among independent and dependent variables will be highlighted. Accordingly, given some assumptions, it is verified how well channel morphology and hydraulic components are intertwined and combined with AHG parameters and how categorizing river monitoring stations according to these characteristics will be practical and useful for further studies. For instance, the application of AHG parameters in modifying numerical hydraulic routing coefficients will result in an improvement in predictability of flood routing schemes (here, Muskingum-Cunge). The thesis will be concluded by the analysis of trade-off between computation time and accuracy or complexity vs. simplicity among advanced, hydrodynamic (HEC-RAS 2D) vs. low-complexity (AutoRoute and HAND) models that is also an alternative way to affirm the advantage of idealizing or simplifying a hydraulic system over-relying on time- and energy-costly approaches.

Indexing (document details)
Advisor: Fekete, Balazs M.
Commitee: Bjerklie, David, Devineni, Naresh, Dingman, S. Lawrence, Khanbilvardi, Reza
School: The City College of New York
Department: Civil Engineering
School Location: United States -- New York
Source: DAI-B 80/06(E), Dissertation Abstracts International
Subjects: Civil engineering, Water Resource Management
Keywords: At-a-station hydraulic geometry, Climate change, Flood mapping and analysis, River morphology and geophysics, Simplified hydraulic routing, Statistical analysis
Publication Number: 13422984
ISBN: 978-0-438-82649-6
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