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Abstract:The regional frequency analysis of extreme annual rainfall data is a useful methodology in hydrology to obtain certain quantile values when no long data series are available. The most crucial step in the analysis is the grouping of sites into homogeneous regions. This work presents a new grouping criterion based on some multifractal properties of rainfall data. For this purpose, a regional frequency analysis of extreme annual rainfall data from the Maule Region (Chile) has been performed. Daily rainfall data series of 53 available stations have been studied, and their empirical moments scaling exponent functions K(q) have been obtained. Two characteristics parameters of the K(q) functions (γ max and K(0)) have been used to group the stations into three homogeneous regions. Only five sites have not been possible to include into any homogenous regions, being the local frequency analysis of extreme daily rainfall the most appropriate method to be used at these locations.

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México. Av. de los Barrios núm 1. Los Reyes Iztacala, Tlalnepantla, Estado de México. MÉXICO. RESUMENE n el presente artículo se realiza un análisis comparativo de tres métodos para obtener hidrogramas unitarios sintéticos (HUS). Los métodos de Snyder, de "U.S. Bureau of Reclamation" y el de Témez se analizaron en dos cuencas de la zona mediterránea de Chile. Para ello, se realizó una caracterización morfológica y vegetacional de cada cuenca. Además, se utilizó la información de tres tormentas reales con intensidades clasificadas como alta, media y baja, a fin de obtener los hidrogramas de escorrentía directa (HED) para ambas cuencas. La escorrentía asociada a los eventos de precipitación se obtuvo utilizando la metodología del número de curva. Los resultados demostraron que, a nivel general, los HUS utilizados no presentaron diferencias estadísticamente significativas (P = 0.05) para ambas cuencas. Por otra parte, la metodología del HUS de Snyder fue la única que detectó diferencias estadísticamente significativas en los HED respecto a los otros métodos y sólo bajo una tormenta de alta intensidad en la cuenca Cunculén. ABSTRACTT his paper compares three methods to obtain synthetic unit hydrographs (SUH). The Snyder (modified for Chile by Astorga and Benítez), the US Bureau of Reclamation, and the Témez methods are analyzed on two watersheds located in Mediterranean areas of Chile. To do so, each watershed was characterized in terms of its morphology and vegetation type. In addition, data from three actual storms, with high, medium, and low rainfall intensities, were used to obtain direct runoff hydrographs (DRH) for both watersheds. The NRCS Curve Number method was used to estimate runoff responses to storm events. Our results suggest that, in general, the SUH used had no significant differences between watersheds. On the other hand, the Snyder SUH method was the only one that found significant differences in the DRHs relative to the other methods and only under a highintensity storm in the Cunculén watershed.