Avaliação do modelo Soil and Water Assessment tool (SWAT) na bacia hidrográfica do Ribeirão Taquaruçu

Abstract

Due to the process of city growth and agricultural activity there are impacts that affect water resources such as scarcity, degradation of water quality and consequent conflicts of uses. In this context, hydrological models are important tools to evaluate the hydrological behavior of watersheds, and can also be used to predict scenarios to verify the impact of land use and occupation. Thus, the present study had as purpose to evaluate the performance of the Soil and Water Assessment Tool (SWAT) model in the flow simulation in the Ribeirão Taquaruçu Watershed. The automatic calibration was performed with the SWAT-CUP program, in a daily step, with data from two BRK Ambiental fluviometric stations from April 2013 to July 2014, while data from August 2014 to August 2015 were used in the period of validation. The sensitivity analysis was performed with 14 parameters chosen considering the most significant ones for the simulation of flow in the Cerrado region. The results of the sensitivity analysis indicated that the most influential parameters are the SOL_K (saturated hydraulic conductivity of the soil) and CN2 (number curve for condition II). The Nash-Sutcliffe objective functions (NSE) and the determination coefficient (R2) were used to evaluate the performance of the model, which indicated, in the calibration period, the following values: - 0.05 and 0.55 (sub-basin 1); 0.51 (sub-basin 3), respectively. In the validation period, the following results were presented for NSE and R2: 0,44 and 0,54 (sub-basin 1); 0.24 and 0.29 (sub-basin 3), in that order. Considering that the object of study is important because it is responsible for a large part of the water supply of the municipality of Palmas – TO and that the software was not able to simulate the minimum flows adequately, the results are considered unsatisfactory.