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A MODIFIED RATIONAL FORMULA FOR FLOOD DESIGN IN SMALL BASINS 1
Author(s) -
Hua Jiapeng,
Liang Zhongmin,
Yu Zhongbo
Publication year - 2003
Publication title -
jawra journal of the american water resources association
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.957
H-Index - 105
eISSN - 1752-1688
pISSN - 1093-474X
DOI - 10.1111/j.1752-1688.2003.tb03689.x
Subject(s) - flood myth , hydrograph , hydrology (agriculture) , structural basin , storm , interval (graph theory) , ellipse , mathematics , meteorology , environmental science , computer science , geology , geometry , combinatorics , geotechnical engineering , geomorphology , physics , geography , archaeology
New formulas and procedures under the framework of the Rational Formula are presented that are applicable to flood design problems for a small basin if the geometry of the basin can be approximated as an ellipse or a rhombus. Instead of making the assumption in the traditional rational formula that the rainfall is uniformly distributed in the whole duration ( D w ) of a design storm, the new method modifies that assumption as: the rainfall is uniformly distributed only in each time interval CD) of the design storm hyetograph, thus extending the rational formula applicable to the case that the rainfall duration is less than the basin concentration time ( T c ). The new method can be applied to estimate the flood design peak discharge, and to generate the flood hydrograph simultaneously. The derivation of the formulas is provided in detail in this paper, and an example is also included to illustrate how to apply the new formulas to the flood design problems in small basins.