Abstract

ALONSO-SANCHEZ, Homero; IBANEZ-CASTILLO, Laura Alicia; ARTEAGA-RAMIREZ, Ramón  and  VAZQUEZ-PENA, Mario Alberto. Runoff Curve Identification in Three Micro-Basins of the Coatan River, Chiapas, Mexico. Tecnol. cienc. agua [online]. 2014, vol.5, n.4, pp.153-161. ISSN 2007-2422.

The curve numbers (CN) method by the Soil Conservation Service (SCS) has applications in the field of hydrology and has been widely used in many countries, including Mexico. Nevertheless, these values were obtained in United States basins and pertain to very general land use categories. Therefore, using them can result in errors. This study identified and compared the runoff curve number for three micro-basins in the Coatan River watershed, in Chiapas, for several rain events ranging from 13 to 36 events during 2011. This watershed is located in the Mexican humid tropics. On the one hand, values were used from SCS tables corresponding to the micro-basins and its events, with the respective corrections for antecedent moisture and slope. On the other hand, NC values were calculated from direct rainfall and runoff measurements. Rainfall was measured using rain gauges and runoff using water level recorders near the watershed and at its outlet. Both NC were compared, those obtained from the measurements (69 in Vega de los Gatos, 55 in Progreso and 72 in Chanjale) and those provided by SCS tables (79 for Vega de los Gatos, 79 for Progreso and 78 for Chanjale). Significant differences in means were found between these two sets of data. These results are attributed to the use of SCS tables that do not have the required land use, thereby needing to subjectively use those which are closest, resulting in accuracies.

Keywords : Runoff depth; measurement of rainfall and runoff in tropical watersheds; runoff coefficients in tropical watersheds.

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