Abstract

MOZO, Joaquín; VARNI, Marcelo; ARES, María Guadalupe  and  CHAGAS, Celio Ignacio. Rainfall-runoff hydrological modeling of an agricultural watershed of Azul district, Buenos Aires. Cienc. suelo [online]. 2020, vol.38, n.1, pp.121-132. ISSN 1850-2067.

The precipitation-runoff processes were analyzed in a micro-basin under agricultural use (566 ha) located in the Hilly/Perirange area of Azul District, Buenos Aires, Argentina. The hydrological model 3.2 HEC-HMS was used in combination with the QGIS software, dividing the basin into several sub-basins interconnected by an internal channel. For the rainfall-runoff model, the NRCS curve number method was considered. CN values were calculated for 2012 using two procedures: a) the original SCS-CN method and b) the Hawkins method. When an adequate adjustment between the observed data and the estimated values was not achieved, a CN was finally used according to the calibration of the model using its own historical records. The correlation coefficient and the Nash Sutcliffe efficiency coefficient were greater than 0.7 for all floods. The mean root square of the error yielded low values indicating an acceptable model fit. Then, an event-to-event sensitivity analysis was performed. To this end, two of the parameters included in the model (curve number and lag time) were subjected to the sensitivity analysis. In turn, the CN values estimated for the adjustment were analyzed versus precipitation data (mm), considering all the floods and including as third variable: a) preceding rainfall and b) precipitation duration. Based on historical flood data available for 2012, the model predicted acceptably maximum discharge, runoff volume and peak time. These results highlight the need to obtain CN values calibrated in situ. Under this condition, HECHMS can be adequate to model the hydrological response of the studied basin for the analysis of available hydro-meteorological data and to predict future floods, which is relevant for land management and conservation of the region.

Keywords : Rainfall; runoff; CN; HEC-HMS model.

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