Abstract

RAMIREZ CRUZ, Hilario; LOPEZ VELASCO, Osiel  and  IBANEZ CASTILLO, Laura Alicia. Estimation of monthly 30 minute rainfall intensity based on pluviometric data. Terra Latinoam [online]. 2015, vol.33, n.2, pp.151-159. ISSN 2395-8030.

Some hydrological models for the evaluation of water erosion, such as the Soil and Water Assessment Tool (SWAT), require input data such as monthly half-hour rainfall intensity (I30), which should be obtained preferentially based on historical pluviographic records or an automatic meteorological gage (AMG). However, in absence of a pluviograph or AMG, the objective of this work was to obtain the monthly I 30 based on pluviometric data. In order to calculate I 30 based on 24 hour rainfall data, the following equations were applied: Bell (1969), Chen (1983), and the World Meteorological Organization (WMO, 2009). These equations were applied in the Copalita, Oaxaca, watershed using data from the four rainfall gaging stations: Pluma Hidalgo, San Francisco Ozolotepec, San Miguel Suchixtepec, and La Hamaca. Part of the methodology consisted of obtaining maximum monthly rainfall depths for half-hour duration and return periods, T, over 10, 20, 25, 50, and 100 years. The results were validated with intensity isohyetals from the Mexican Secretaría de Comunicaciones y Transportes (SCT), which were based on pluviograph data (SCT, 2000), (SCT, 2014) for several return periods. The statistical variance analysis and average comparison for T of 10 years (Tukey, P > 0.05) showed that the SCT data are not significantly different from those of Chen y OMM, but they are different from those of Bell. Finally we recommend factors for calculating the I 30 of 10 years of return based on 24 hour, 10-year rainfall depth, for each meteorological station included in the study.

Keywords : short duration rainfalls; water erosion; SWAT; coast of Oaxaca watershed.

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