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You are here : eLibrary : IAHR World Congress Proceedings : 36th Congress - The Hague (2015) ALL CONTENT : Water resources and hydroinformatics : Development of an anisotropic spatial interpolation method for velocity in the meandering river chan...
Development of an anisotropic spatial interpolation method for velocity in the meandering river channel
Author : HOJUN YOU(1), DONGSU KIM(2)
ABSTRACT
Understanding of the two-dimensional velocity field is crucial in terms of analyzing various hydrodynamic and fluvial
processes in the riverine environments. Until recently, many numerical models have played major roles of providing
such velocity field instead of in-situ flow measurements, because there were limitations in instruments and
methodologies suitable for efficiently measuring in the broad range of river reaches. In the last decades, however, the
advent of modernized instrumentations started to revolutionize the flow measurements. Among others, acoustic Doppler
current profilers (ADCPs) became very promising especially for accurately assessing streamflow discharge, and they are
also able to provide the detailed velocity field very efficiently. Thus it became possible to capture the velocity field only
with field observations. Since most of ADCPs measurements have been mostly conducted in the cross-sectional lines
despite their capabilities, it is still required to apply appropriate interpolation methods to obtain dense velocity field as
likely as results from numerical simulations. However, anisotropic nature of the meandering river channel could have
brought in the difficulties for applying simple spatial interpolation methods for handling dynamic flow velocity vector,
since the flow direction continuously changes over the curvature of the channel shape. Without considering anisotropic
characteristics in terms of the meandering, therefore, conventional interpolation methods such as IDW and Kriging
possibly lead to erroneous results, when they dealt with velocity vectors in the meandering channel. Based on the
consecutive ADCP cross-sectional measurements in the meandering river channel, the present study attempts to
develop a specialized velocity interpolation framework and an ArcGIS-based software named A-VIM, which
encompassed anisotropic or multi-directional reference ranges following the varying streamwise direction as well as
channel geometry. The geographic coordinate with the measured ADCP velocity was converted from the conventional
Cartesian coordinate (x,y) to a curvilinear coordinate (s,n). The results from application of A-VIM showed significant
improvement in accuracy as much as 41.5% in RMSE. Estimating of two-dimensional velocity based on ADCP was
rarely compared with other in-situ flow measurements or two-dimensional numerical model. Therefore, The proposed
method can be a method that validate result of two dimensional velocity field based on other methods.
File Size : 610,240 bytes
File Type : Adobe Acrobat Document
Chapter : IAHR World Congress Proceedings
Category : 36th Congress - The Hague (2015) ALL CONTENT
Article : Water resources and hydroinformatics
Date Published : 19/08/2015
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