Drenaje de Carreteras. Comparación Entre las Curvas I–d–T_r Obtenidas Mediante Mediciones con Pluviógrafo y las Obtenidas con los Métodos Indirectos de Chen y de Bell

Surface runoff generated by rainfall can affect highways, if not drained properly. Therefore, it is necessary to design bridges, culverts, ditches and counterditches to drain the runoff volumes. Most of these drainage structures are located in small basins, with fast response to high intensity and short duration rainfall.

The hydraulic design of new drainage structures or the revision of existing structures requires information about the magnitude of the rainfall events. This information is included on Rainfall intensity – duration – Frequency ( I – d – F ) curves known as Isohyets and are based on pluviograph measurements.

The distribution and number of pluviographs in Mexico is limited, therefore the information is scarce. Because of this, there has been a tendency to use indirect methods to calculate rainfall intensities for short durations using 1 hour and 24 hours rainfall depths. The most commonly used methods are Chen’s and Bell’s.

In order to determine the degree of concordance of these methods with measurements in different regions of Mexico, I – d – F curves were prepared using the Isohyets maps elaborated by Secretaría de Comunicaciones y Transportes (SCT) in 2000 and applying the indirect methods proposed by Chen and Bell.

The results obtained with these three alternatives were compared and it was observed that these methods do not agree with the measurements taken in different parts of Mexico.

In this research, some proposals are included to improve the distribution of pluviographs, rainfall measurement and its statistical processing.

Key words: rainfall, rainfall intensity, frequency (return period), pluviograph, pluviometer, I – d – F curves, isohyet maps (I – d – F maps).