Abstract
ABSTRACT This study aimed to use global sensitivity analysis (GSA) methods to evaluate the sensitivity of the SAC-SMA hydrologic model parameters in the estimation of daily flows of the Piracicaba river basin. The study was carried out in three sections of flow monitoring of the Piracicaba river basin, with an area of 5,304.0 km2 and located in the State of Minas Gerais, Brazil. For the global sensitivity analysis of the SAC-SMA model, the Morris and Sobol methods were used. The model parameters showing high sensitivity were UZFWM, which represents the free water depth in the upper zone of the soil and interferes with the subsurface flow and groundwater aquifer recharge; ADIMP, which represents the additional impermeable area of the basin and interferes with the direct runoff generation; and LZPK, LZSK, LZFPM, and LZFSM, which are related to the base flow of the basin. The results showed that most of the SAC-SMA model parameters do not provide expressive variations in the output variable, most of the SAC-SMA model parameters with high sensitivity are the intervenient in the base flow, and the Morris method should be used as a preliminary analysis to the use of the Sobol method.
Highlights
Hydrologic simulation models allow understanding the hydrologic behavior of a basin, making possible their use for the evaluation of strategies of water resources management and prediction of extreme events (Andrade et al, 2013).Several hydrologic models have been developed and used worldwide with a variety of purposes (Devia et al, 2015)
Based on the interpretation of values of mean (μ∗) and standard deviation (σ) of the elementary effects obtained in the monitoring sections 56696000 (Mário de Carvalho) and 56610000 (Rio Piracicaba), five parameters among the 13 of the SAC-SMA model it was identified by the Morris method, providing higher variations in the output variable, i.e. the daily flow (Figures 3a and b)
Among the parameters highlighted by these authors, LZTWM presented sensitivity in the three monitoring sections of the flow of the Piracicaba river basin, while PCTIM showed high sensitivity only in the section Carrapato
Summary
Hydrologic simulation models allow understanding the hydrologic behavior of a basin, making possible their use for the evaluation of strategies of water resources management and prediction of extreme events (Andrade et al, 2013).Several hydrologic models have been developed and used worldwide with a variety of purposes (Devia et al, 2015). Even considering the importance of hydrologic modeling, the great difficulty of its practical application is the calibration/validation and understanding of the behavior of hydrological models with a high number of parameters In this context, the sensitivity analysis is an important tool to be adopted before the calibration/validation process and flow estimation (Shin et al, 2013; Song et al, 2015). Sensitivity analysis allows evaluating the influence of input data and their interactions on the performance of mathematical models The results of this analysis allow understanding the behavior of hydrologic models and are useful in the parameterization, optimization, and quantification of model uncertainties (Song et al, 2015)
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