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[EN] The two-parameter gamma function (G2P) design storm is a recent methodology used to obtain synthetic hyetographs especially developed for urban hydrology applications. Further analytical developments on the G2P design storm are presented herein, linking the rainfall convectivity n-index with the shape parameter of the design storm. This step can provide a useful basis for future easy-to-handle rainfall inputs in the context of regional urban drainage studies. A practical application is presented herein for the case of Valencia (Spain), based on high-resolution time series of rainfall intensity. The resulting design storm captures certain internal statistics and features observed in the fine-scale rainfall intensity historical records. On the other hand, a direct, simple method is formulated to derivate the design storm from the intensity-duration-frequency (IDF) curves, making use of the analytical relationship with the n-index.

[EN] The present research develops a systematic application of a selected family of 11 well-known design storms, all of them obtained from the same rainfall data sample. Some of them are fully consistent with the intensity¿duration¿frequency (IDF) curves, while others are built according to typical observed patterns in the historical rainfall series. The employed data series consists on a high-resolution rainfall time series in Valencia (Spain), covering the period from 1990 to 2012. The goal of the research is the systematic comparison of these design storms, paying special attention to some relevant quantitative properties, as the maximum rainfall intensity, the total cumulative rainfall depth or the temporal pattern characterising the synthetic storm. For comparison purposes, storm duration was set to 1 h and return period equal to 25 years in all cases. The comparison is enhanced by using each of the design storms as rainfall input to a calibrated urban hydrology rainfall¿runoff model, yielding to a family of hydrographs for a given neighbourhood of the city of Valencia (Spain). The discussion and conclusions derived from the present research refer to both, the comparison between design storms and the comparison of resulting hydrographs after the application of the mentioned rainfall¿runoff model. Seven of the tested design storms yielded to similar overall performance, showing negligible differences in practice. Among them, only Average Variability Method (AVM) and Two Parameter Gamma function (G2P) incorporate in their definition a temporal pattern inferred from empirical patterns identified in the historical rainfall data used herein. The remaining four design storms lead to more significant discrepancies attending both to the rainfall itself and to the resulting hydrograph. Such differences are ~8% concerning estimated discharges

Las tormentas de diseño son un input clave dentro de la información necesaria para el diseño de infraestructuras hidráulicas. Existen numerosas metodologías de cálculo de tormentas de diseño desarrolladas durante la segunda mitad del siglo XX mundialmente y que pueden ser clasificadas en dos grupos principalmente. En primer lugar, se tienen aquellas basadas exclusivamente en curvas IDF, como son el hietograma rectangular (1970) o el método de los bloques alternos (1957), el cual ha sido el más extendido por su simplicidad de cálculo a pesar de los inconvenientes derivados de su planteamiento. En segundo lugar, se encuentran las tormentas de diseño basadas en registros de precipitación reales con la finalidad de obtener una aproximación más realista. Estos tienen en cuenta otras variables además de la intensidad media máxima, que si bien puede ser suficiente para el diseño de ciertos elementos, puede ser insuficiente en algunos casos en los que obtener un patrón temporal muy alejado de la realidad climática de la zona puede derivar en un diseño inadecuado. Ejemplos de este segundo enfoque son los métodos de Huff (1967) y posterior Illinois State Water Survey design storm (1974), Pilgrim y Cordery (1975), las tormentas de diseño del Servicio Atmosférico Ambiental canadiense (1980), Flood Studies Report (1975), etc. Una de las metodologías más recientemente desarrolladas dentro de esta segunda categoría es la realizada por García-Bartual y Andrés-Doménech (2017), mediante una función gamma de dos parámetros la cual pretende ser empleada en aplicaciones reales y servir de alternativa a las tormentas de diseño aplicadas en zonas mediterráneas. El siguiente trabajo describe cada uno de los métodos anteriores y otros, para después aplicar varios de ellos a un mismo conjunto de datos disponibles. Los datos se han extraído de un análisis previo de series pluviométricas cinco-minutales pertenecientes a un pluviómetro situado en la ciudad de València. El objetivo es realizar u, Design storms are a key input to the necessary information for hydraulic infrastructures design. There are numerous methodologies for calculating design storms developed during the second half of the 20th century worldwide and they can be classified, mainly, into two groups. First, there are those based exclusively on IFD curves, such as the rectangular hyetograph (1970) or the alternative blocks method (1957), which has been the most widespread due to its simplicity of calculation despite the drawbacks derived of its approach. Second, there are design storms based on real rainfall records in order to obtain a more realistic approach. These take into account other variables in addition to the maximum average intensity, which although it may be sufficient for the design of certain elements, may be insufficient in some cases in which obtaining a temporal pattern very far from the climatic reality of the area can be derived in an inappropriate design. Examples of this second approach are the methods of Huff (1967) and later Illinois State Water Survey design storm (1974), Pilgrim and Cordery (1975), the design storms of the Canadian Environmental Atmospheric Service (1980), Flood Studies Report (1975). ), etc. One of the most recently developed methodologies within this second category is that carried out by García-Bartual and Andrés-Doménech (2017), through a gamma function of two parameters, which is intended to be used in real applications and serve as an alternative to the storms of design applied in Mediterranean areas. The following work describes each of the above methods and others, and then apply several of them to the same set of available data. The data have been extracted from a previous analysis of five-minute rainfall series belonging to a rain gauge located in the city of València. The objective is to perform a comparative synthesis of the design storms obtained according to selected parameters, such as the maximum intensity and its temporal location, th