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The effect of the time distribution of rainfall intensities on small watershed floods: technical report

dc.contributor.authorDowner, Richard Neal, author
dc.contributor.authorColorado State University, Department of Civil Engineering, publisher
dc.date.accessioned2019-09-17T19:45:32Z
dc.date.available2019-09-17T19:45:32Z
dc.date.issued1967-09
dc.descriptionCER67-68RND14.
dc.descriptionSeptember 1967.
dc.descriptionIncludes bibliographical references (pages 113-117).
dc.description.abstractThe time-intensity pattern of the storm rainfall is described by taking the moments of area of the hyetograph about the intensity-axis and about the time-axis. The effect of these parameters on the shape of the hydrograph is studied by means of multiple regressions. Three groups of hydrograph parameters are used as dependent variables in the regressions. They are: the moments of area of the hydrograph about the discharge-axis; the traditional hydrograph parameters of volume, peak and rise time; and the parameters of a mathematical function fitted to the hydrograph. The fitted function was an incomplete gamma function of the form q = q0 ty e-y(t-r)/ryr where q is the unit discharge in inches/hour, q0 is the peak unit discharge in inches/hour, t is the time in minutes, Y is shape parameter with the units of reciprocal minutes, r is the rise time in minutes, and e is the base of Naperian logarithms. The fitting process was accomplished by the method of weighted least squares, whereby the squared deviations between the observed discharge and computed discharge were weighted in proportion to the observed discharge. The results indicate that the moments of the hyetograph are objective descriptors of the time distribution of rainfall intensities. All three groups of hydrograph parameters can be predicted with nearly equal accuracy. The similarity of the relationships for the observed peak and the fitted peak, and the observed rise time and the fitted rise time attest to the methodology of fitting the three-parameter gamma function to the observed hydrograph.
dc.format.mediumtechnical reports
dc.identifier.urihttps://hdl.handle.net/10217/198135
dc.languageEnglish
dc.language.isoeng
dc.publisherColorado State University. Libraries
dc.relationCatalog record number (MMS ID): 991020770529703361
dc.relation.ispartofCivil Engineering Reports
dc.relation.ispartofCER, 67/68-14
dc.rightsCopyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright.
dc.subject.lcshHydraulics -- Tables
dc.subject.lcshRain and rainfall
dc.subject.lcshFlood control
dc.titleThe effect of the time distribution of rainfall intensities on small watershed floods: technical report
dc.typeText
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