Abstract

QUEVEDO-TIZNADO, J. Antonio et al. Direct runoff events simulation in small basins with the HIDRAS model. Agrociencia [online]. 2016, vol.50, n.7, pp.787-798. ISSN 2521-9766.

Direct runoff is the integrated effect of rain, interception, evapotranspiration, infiltration and depth of overland flow at a specific point in the watershed. Conversion of precipitation to runoff is a complex process that depends on both spatial and temporal distribution of the rains and the physical characteristics of the watershed. This study had the objective of proposing procedures for simulating direct runoff at the event scale in small watersheds. We selected two experimental watersheds of Mexico with different characteristics in terms of size, location, vegetation type, topography, and rainfall regime: the Mixcoac River watershed in the Valley of Mexico, and the Cerro Blanco runoff unit, in Tabasco. The simulations were conducted with our own hydrological model, which we call HIDRAS, in which the methods proposed by Haan et al. (1994) and Sánchez and Gracia (1997) were implemented to calculate hydrographs using a scheme of unitary response to correct the effects of regulation. Flow routing was done using an integral form of the dynamic advection-diffusion equation. The hydrographs resulting from the simulation were assessed comparing their main elements quantitatively with the measured hydrographs and in terms of the NashSutcliffe index (NS). The results were favorable after applying calibration techniques. NS efficiency indexes of 0.75 and 0.83 were obtained for the first and second study cases, respectively. In the Cerro Blanco runoff unit, for which the database is ample, the model was validated: NS was 0.81 and 0.74 when events previous and posterior to that used for calibration were simulated. This validation allows us to recommend application of the methodology developed in this study to other cases of interest with characteristics similar to those presented here.

Keywords : Synthetic hydrographs; HIDRAS; distributed hydrological modelling; hydrograph calibration.

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