Abstract

SALAS AGUILAR, Víctor Manuel et al. Non-linear modelling separation of the base flow in subbasins of Chiapas, Mexico. Terra Latinoam [online]. 2015, vol.33, n.4, pp.285-297. ISSN 2395-8030.

Base flow is an important element in hydrological modelling in a basin. Its study is key in estimating the rainfall-runoff relationship. In this work, base flow was separated from total stream flow in three subbasins in Chiapas. Variation in potential recharge of shallow aquifers was also evaluated. Recession curves were calibrated monthly using the nonlinear relationship between storage-discharge of an aquifer. The model was calibrated monthly based on a parameter (a). It was associated with the monthly stream flow quantile regression approach (RC) for parameter values on a daily scale. Recession curves for the different subbasins, fit the proposed model (R2 > 0.85) well. The use of quantile regression allowed adjusting a potential model in the outliers, so that base flow did not exceed total stream flow. Base flow indices (IBI) were 0.74, 0.69 and 0.54, for the subbasins Caimacán, Zanatenco and Tulijá, respectively. The recharge potential exhibited strong seasonality, product of high rainfall in the area. Recharge was higher for subbasins Caimacán and Zanatenco. The subbasin Tulijá is located in a small aquifer, which limits greater recharge. It was shown that a nonlinear model to analyze the recession curve is applicable to assessing separation of base flow from total stream flow in subbasins with different hydrogeological characteristics.

Keywords : underground water balance; storage-discharge relationship; quantile regression.