Abstract

ARES, M. Guadalupe; VARNI, Marcelo; CHAGAS, Celio  and  ENTRAIGAS, Ilda. Runoff curve number calibration of a 116 km² agricultural basin, Buenos Aires province, Argentina. Agrociencia [online]. 2012, vol.46, n.6, pp.535-541. ISSN 2521-9766.

In the mountainous area of Buenos Aires, Argentina, an increase in precipitation and in cultivated area has contributed to generating excessive runoff that has had severe impact on the region and on soil water erosion. The rain-runoff ratio in this region can help estimate the effects of floods. The local values of the runoff curve number (N) were calculated for the basin of the Arroyo Videla (Buenos Aires, Argentina), and its relationship to rainfall events was studied parting from daily rain data and runoff volumes. Values of 51 to 99 were obtained, and the most frequent were between 60 and 90. The relationship between N and precipitation exhibited a standard pattern that allowed adjusting an asymptotic value of 57. Rains less than 15 mm were associated with N between 85 and 90, while rains between 15 and 85 mm were related to N of 60 to 85. There was concordance between intermediate observed N and tabulated values of this parameter associated with each plant cover. This highlights the importance of obtaining local values of the studied variable to appropriately implement the method in basins of 100 km².

Keywords : daily rainfall; runoff; runoff curve number; basin size; hydrographs.