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Theoretical assessment of changes in design flood peak of an overland plane for two opposing urbanization sequences
Author(s) -
Wong Tommy S. W.,
Li Yunjie
Publication year - 1999
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/(sici)1099-1085(19990815)13:11<1629::aid-hyp833>3.0.co;2-s
Subject(s) - urbanization , flood myth , surface runoff , permeability (electromagnetism) , environmental science , hydrology (agriculture) , geotechnical engineering , geology , geography , chemistry , ecology , biochemistry , archaeology , membrane , biology
By considering urbanization on an overland plane as a process whereby a relatively rough, permeable surface is gradually replaced by a relatively smooth, less permeable surface, the effect of urbanization sequence on the flood peak is theoretically assessed by the kinematic wave method. In the assessment, two opposing urbanization sequences are considered: one from downstream to upstream, and the other from upstream to downstream. The assessment is carried out in terms of the individual effect as well as the combined effect of the Manning resistance coefficient and the runoff coefficient. For both urbanization sequences and for all degrees of urbanization, the assessment shows that surface conversion from rough to smooth, or from permeable to less permeable causes the flood peak to increase. A comparison of the individual effects shows that for equal reductions in surface roughness and permeability, the reduction in permeability causes greater increases in the flood peak compared with the reduction in surface roughness. For a partially urbanized plane and for the same degree of urbanization, due to the partial area effect, urbanization at the downstream end generally causes greater increases in the flood peak. In terms of urbanization sequence, the downstream to upstream urbanization sequence generally causes greater increases in the flood peak. The effect of urbanization sequence on the flood peak, however, is only significant for the larger reductions in surface roughness and permeability. Finally, a comparison of the results of this study with those obtained from drainage basins shows that for most of the results from the basins, they correspond to those for the small reductions in surface roughness and permeability on an overland plane. For these cases, the effect of urbanization sequence on the flood peak is small. Copyright © 1999 John Wiley & Sons, Ltd.