Mejora de los parámetros de cálculo del modelo del número de curva y su validación mediante un modelo hidrológico distribuido

Resumo

This work proposes a set of improvements to the curve number method for runoff estimation. It deals with a more precise procedure to the calculation of the hydrological soil group as well as the reduction of ambiguity in determining the antecedent soil moisture condition. For hydrological soil group, a previous deep analysis of the method has been performed from the definitions of its reference organism. The proposed procedure determines a continuous hydrological soil group index by means of combining pedotransfer estimations of hydraulic conductivity of soil horizons with the soil depth where minimum hydraulic conductivity occurs. The continuous index should reduce the probability of error arising from the traditional sharp classes. The continuous index obtained of hydrological soil group leads to the proposal of continuous curve numbers. This has been done by shifting from the standard tables to a set of functions with the hydrological soil group index as independent variable. The antecedent moisture condition (AMC) is based so far on previous rainfall, not taking in account pedologic parameters. Soil water balance has been transformed from monthly to daily in order to propose two continuous models for AMC, based on the water content evolution related to time. To validating the proposals made, as well as their level of improvement, a test has been conducted in a controlled watershed, containing five meteorological automated stations in South western Spain. Real runoff hydrograms of several storms were compared to the results of a distributed hydrological model that uses curve number, running on a geographical information system.