Análise da eficiência do modelo SWAT para simulação dos processos hidrossedimentológicos, utilizando diferentes abordagens de calibração

Abstract

Anthropogenic actions have led to various consequences for the environment, posing significant challenges for those responsible for managing and handling watersheds. One available approach for investigating these issues is the modeling of hydrosedimentological processes, with the Soil and Water Assessment Tool (SWAT) being a widely used model for watershed studies. This research assessed the efficiency of the SWAT model in simulating hydrosedimentological processes in the Taboão/RS watershed. The goal was to identify which equations and methods for evapotranspiration, runoff propagation, and sediment transport in channels, available in the model routines, best represent the present processes. This consideration involved the daily scale of hydrosedimentological output data from the model and different temporal resolutions of precipitation input data. Calibration of flow utilized data from 2013 (from March onwards), 2014, and 2016, with 2011 and 2012 designated as the warm up periods. Sediment production calibration used data from 2013 and 2015, with 2011 and 2012 also considered for warming up. In the validation process, 2015 data were employed for flow estimation, while 2014 and 2016 data were used for sediment production. A total of 27 parameters were analyzed for flow calibration, 22 for the Bagnold equation, and 20 for the Yang equation in sediment transport, degradation, and channel input calculation. Simulation results for flow, evaluated by the Nash-Sutcliffe coefficient (NS), indicated values of 0.66 and 0.33 for calibration using the GA and CN methods, respectively, in the best scenarios. In validation, these values were 0.76 and 0.44 for the GA and CN methods, respectively. Regarding daily sediment production calibration, the NS was 0.73 for both GA and CN methods, while in validation, these values were 0.64 and 0.48 for GA and CN methods, respectively. The simulation results underscore that the most accurate representation of flow and daily sediment production in the Taboão/RS watershed is achieved by incorporating hourly precipitation data, the Green & Ampt infiltration method, the Penman-Monteith evapotranspiration equation, the Variable Storage runoff propagation method, and the Bagnold sediment transport method. The combined use of these methods demonstrated superior performance, showcasing greater predictive capability for observed hydrosedimentological processes in small agricultural watersheds, such as the Taboão watershed, characterized by the prevalence of subsurface and underground runoff.