Calibration technique for modeling the São Francisco watershed, Brazil, using SWAT

Abstract

The Soil and Water Assessment Tool (SWAT) is a hydrosedimentological model whose main focus is to evaluate the impacts of changes in land use on the quality and quantity of water in watersheds. For these evaluations to be adequate, considering the representativeness of the processes simulated by the model, it is necessary to carry out the calibration procedure. Many modelers find a great challenge in this essential stage of modelling. There are a wide variety of parameters to consider, different algorithms, as well as different objective functions. Another aspect to be highlighted is the fact that the processing time can be high, when considering representative watersheds, as is the case of the São Francisco River basin, Brazil (639,219 km²). To meet the demand for the creation of an integrated water management model for BIS countries (Brazil, India and South Africa) under climate change scenarios, the São Francisco basin was calibrated. This scientific note aims to provide an overview of the calibration procedure using flow data in a monthly time step from 1961 to 2016 in the studied basin. The SWAT model calibrated for the São Francisco River basin can be used to analyze climate change scenarios and their impacts on the water availability of the basin, thus supporting decision-making on water resources and the creation of a management model. integrated with the other BIS countries.