Hydrological simulation in a basin of typical tropical climate and soil using the SWAT Model Part II: Simulation of hydrological variables and soil use scenarios

Study region: The study was developed for the Pomba river basin, which is located in southeast region of Brazil in the continent of South America. Study focus: Hydrological simulation may be used to estimate the water availability, flood streamflows and the basin's hydrological response due to changes in soil use. Thus, aimed to apply the SWAT model, version 2005, to simulate (i) the minimum and maximum annual daily streamflows associated to different return times, (ii) minimum reference streamflows for water rights, and (iii) scenarios of changes in soil use. Were simulated the following scenarios of soil use: S1—preservation, considering the permanent preservation areas (PPAs); S2—reforestation expansion and S3—agricultural expansion, considering the replacement of 10% of the basin's total area covered with pastures for eucalyptus and crops, respectively. The current use (S0) being employed as the baseline. New hydrological insights for the region: It was observed that the values of maximum and minimum annual daily streamflows with different return times, and of minimum reference streamflows for water rights simulated by the SWAT did not statistically differ from the values observed according to T-test at 5% probability level. When assessing the effects of changes in soil use, a mean annual reduction in runoff from 13.6, 4.0, and 6.5 mm was observed for scenarios S1, S2, and S3, respectively. Keywords: Maximum streamflows, Minimum streamflows, Reference streamflows, Soil use and cover, Annual runoff, Basi