Using a Hierarchical Approach to Calibrate SWAT and Predict the Semi-Arid Hydrologic Regime of Northeastern Brazil

Abstract

The Paraguaçu watershed in northeastern Brazil faces increasing water scarcity, with water resources unable to meet the increasing demand. Accurate assessment of water availability is thus essential for efficient planning and management of local resources. In this work, the potential of the SWAT model for predicting daily and monthly variability of the hydrologic regime of the Paraguaçu River was assessed. Model calibration/validation followed: (i) A hierarchical framework; (ii) the assessment of maximum, average and minimum streamflow based on paired t-test and linear regression analysis; and (iii) the definition of permanence curves for streamflow with a probability of occurrence of 90% (Q90) and 95% (Q95). The goodness-of-fit indicators revealed a “satisfactory” model performance (model efficiency ranged from 0.42 to 0.83) when predicting streamflow in monitored sub-basins using a unique set of parameters for wet and dry conditions. The flow duration curves also showed that the model underestimated higher flows resulting from extreme events but performed well for flows with exceedance probabilities of <90%. The regression analysis and paired t-test demonstrated that the SWAT model can be used for estimating maximum, average and minimum monthly streamflow in a region where information is insufficient to support water authorities in the decision-making process. The SWAT model can thus be considered adequate for simulating monthly streamflow in the Paraguaçu watershed.

Influence of different methods of potential evapotranspiration estimation in the catolé grande river flow using the swat model

“…According to Schneider et al (2007), evapotranspiration may play a significantly larger role in the water balance of the semi-arid basins because it represents the largest water withdrawal in the system. Santos et al (2018) reinforce the statement by showing that evapotranspiration is responsible for the loss of up to 86% of the water system, after applying the SWAT model to a semi-arid region of Northeast Brazil. Thus, the use of different methodologies in the calculation of potential evapotranspiration (ETo) may represent influences on the calculated amount of available water in the river basin.…”

Using a Hydrologic Model to Assess the Performance of Regional Climate Models in a Semi-Arid Watershed in Brazil

“…Table 1 lists the default and calibrated parameters used during the water balance simulations for the Paraguaçu River basin. These were first tested in Santos et al [20], who calibrated/validated the SWAT model for simulating streamflow in the Andaraí, Fortém, and Iguaçu sub-basins of the Paraguaçu watershed, and applied here now for assessing the accuracy of streamflow predictions in Itaeté and Argoim. Table 2 presents the statistical indicators obtained for the Itaeté and Argoim station after comparing model simulations with field measurements.…”

“…Santos et al [20] applied the SWAT model for simulating streamflow in the Paraguaçu watershed. There, the study area was divided in 69 sub basins and 1906 HRUs based on the digital elevation model (DEM), land use and soil maps available for the region (Figure 2).…”

“…Precipitation data was obtained at Agência Nacional de Águas (ANA), while the remaining weather data was from Instituto Nacional de Meteorologia (INMET). Xavier et al [38] meteorological grid of This study followed Santos et al [20] in performing calibration and validation of the SWAT model by comparing simulated and observed monthly streamflow at two additional hydrometric stations: Itaeté and Argoim ( Figure 2). Daily discharge data at these stations were collected at Agência Nacional de Águas (ANA).…”

“…The dynamical downscaling of the RCM Eta from two GCMs (MIROC5 and HadGEM2-ES) of the Fifth Assessment Report (AR5) dataset [24] provided climate projections for two different This study followed Santos et al [20] in performing calibration and validation of the SWAT model by comparing simulated and observed monthly streamflow at two additional hydrometric stations: Itaeté and Argoim ( Figure 2). Daily discharge data at these stations were collected at Agência Nacional de Águas (ANA).…”