Record Display for the EPA National Library Catalog


Main Title Instantaneous Unit Hydrograph: Its Calculation by the Transform Method and Noise Control by Digital Filtering.
Author Ra, Ramachandra A. ; Delleu, J. W. ;
CORP Author Purdue Univ., Lafayette, Ind. Water Resources Research Center.
Year Published 1971
Report Number TR-20; DI-14-01-0001-1902 ;DI-14-01-0001-3080; OWRR-B-008-IND ;OWRR-B-022-IND; 12330,; B-008-IND(5)
Stock Number PB-202 701
Additional Subjects ( Watersheds ; Rainfall) ; ( Surface water runoff ; Mathematical models) ; Storms ; Fourier transformation ; Laplace transformation ; Linear systems ; Digital filters ; Noise ; Numerical integration ; Indiana ; Instantaneous unit hydrograph
Library Call Number Additional Info Location Last
NTIS  PB-202 701 Some EPA libraries have a fiche copy filed under the call number shown. 07/26/2022
Collation 61p
Linear system analysis techniques are used to evaluate the kernel function (instantaneous unit hydrograph). The methods used were the Fourier, the LaPlace and the Z-transforms. The Z-transform requires the least computer time, but the Fourier transform provides the best insight in the understanding of the methodology. Oscillations of the kernel function were often observed. These were either generated by the computational procedure or by the noise in the data. The oscillations due to the computational procedure are, in general, related to the discretization rate, and often can be controlled by increasing the time step in the discretization of the data. The oscillations due to noise in the data usually can be controlled by digital filtering. Of particular importance is the selection of the truncation values in the numerical integrations in the transform domain, the selection of the proper number of intervals in these integrations and in the discrete convolution which approximates the convolution integral. The properties of the noise attributed to the rainfall excess data are discussed. Computational techniques are illustrated by several examples using data from rural and urban Indiana watersheds. (Author)