Estimation and Regionalization Procedures of Nash's Instantaneous Unit Hydrograph

by Ricardo A. Smith,
Oscar J. Mesa,
Stella Ramirez,

Document Type: Proceeding Paper

Part of: Engineering Hydrology


A 'total fit' method is suggested for computing Nash's instantaneous unit hydrograph (IUH) which minimizes the errors of all ordinates between the observed and generated hydrographs. Previous methods have used the method of moments or minimized peak flow errors. The results of the total fit method are compared with the above two methods using 34 storms from three different river basins. In each case, the total fit criterion produced superior results. A regionalization procedure is also presented and applied to a region in Colombia using nine watersheds and 523 effective rainfall-direct runoff events. The results shows that the proposed regional model gives better results than other methodologies.

Subject Headings: Hydrographs | Numerical methods | Storms | Errors (statistics) | Runoff | Rainfall-runoff relationships | Peak flow | Colombia | South America

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