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Errors of kinematic wave and diffusion wave approximations for time‐independent flows with infiltration and momentum exchange included
Author(s) -
Singh V. P.,
Jain S. K.,
Sherif M. M.
Publication year - 2005
Publication title -
hydrological processes
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.222
H-Index - 161
eISSN - 1099-1085
pISSN - 0885-6087
DOI - 10.1002/hyp.5633
Subject(s) - kinematic wave , froude number , mathematical analysis , mathematics , boundary (topology) , hydrograph , flow (mathematics) , mechanics , physics , ecology , surface runoff , biology
Error equations for kinematic wave and diffusion wave approximations were derived for time‐independent flows on infiltrating planes and channels under one upstream boundary and two downstream boundary conditions: zero flow at the upstream boundary, and critical flow depth and zero depth gradient at the downstream boundary. These equations specify error in the flow hydrograph as a function of space. The diffusion wave approximation was found to be in excellent agreement with the dynamic wave approximation, with errors below 2% for values of KF (e.g. KF ≥ 7·5), where K is the kinematic wave number and F is the Froude number. Even for small values of KF (e.g. KF = 2·5), the errors were typically less than 3%. The accuracy of the diffusive approximation was greatly influenced by the downstream boundary condition. For critical flow depth downstream boundary condition, the error of the kinematic wave approximation was found to be less than 10% for KF ≥ 7·5 and greater than 20% for smaller values of KF . This error increased with strong downstream boundary control. The analytical solution of the diffusion wave approximation is adequate only for small values of K . Copyright © 2005 John Wiley & Sons, Ltd.