Estimation of flood design using the instantaneous hydrograph unit: a case study of the Tecolutla river watershed, Mexico

In this research an instantaneous hydrograph unit (IUh), is used to characterize the flood design at the El Remolino station, located in the Tecolutla river watershed. Rainfall data from 24 stations, all of them located within, or in the vicinity of the watershed was used for the period 1961-1999 to learn about the flood design. From this period we selected 16 more intense storms recorded in the watershed, which generated a peak discharge expenditure greater than 3000 m super(3)/s. The design hydrograph was obtained, using the maximum rainfall within 24 hours, for the return periods of 25, 50 and 100 years. It was found that the design hydrographs for 25 years would have a discharge peak of 21053.7 m super(3)/s, to 50 years of 23653.5 m super(3)/s and 100 years of 26281.4 m super(3)/s. These results indicate that the HUI has an over-estimation in the peak discharge, this over estimation might be because the design storms used have a duration in excess of four days and rainfall in excess of 495.4 mm, 557.2 mm and 618.6 mm for each return period. Finally, the peak discharge estimated, with the HUI, and the peak discharge registered, show a coefficient R super(2) = 0.956, what shows the effectiveness of the model here proposed.