Evapotranspiration represents a significant part on the water balance and, thus, the correct evaluation of this hydrological parcel is relevant when modeling a watershed. The objective of this work is to evaluate the Soil and Water Assessment Tool (SWAT) model’s capability in adequately simulating evapotranspiration in a watershed with predominance of the Brazilian Cerrado biome. Hydrological modeling of the Gama watershed located in the Federal District, which has 57.5% of its total area covered by pristine Cerrado, was conducted. Hydrometeorological and turbulent flow variables have been monitored in weather station and Eddy Covariance (EC) tower, respectively. SWAT simulations were performed for potential evapotranspiration methods: Hargreaves (H), Priestley–Taylor (PT) and Penman–Monteith (PM). Modified versions of SWAT for estimating actual (ET) by Strauch and Volk (2013) (SV) and Arroio Junior (2016) (AR) were also tested. The calibration and verification of the SWAT model, in terms of daily flow, were carried out using a Particle Swarm Optimization algorithm, and fair results were obtained with all the methods evaluated. The actual evapotranspiration (ET) simulated with SWAT (ETsim) using the PM, PT, H, SV and AR methods for a Cerrado hydrological response unit (HRU) were evaluated and compared with the ET obtained using the turbulent flow (Eddy Covariance) method (ETobs). Comparing ETobs and ETsim results, the PM method showed the best fitness and the H and PT methods showed better fit for the dry and the rainy periods, respectively. Although representing an advance on ET modeling, the SV and AR modifications did not improve the response in terms of simulation of the studied area.

中文翻译：

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用 SWAT 模型模拟巴西塞拉多生物群落的蒸散评估

蒸散是水平衡的重要组成部分，因此，在模拟流域时，正确评估该水文地块是相关的。这项工作的目的是评估土壤和水评估工具 (SWAT) 模型在充分模拟以巴西塞拉多生物群落为主的流域中蒸散的能力。对位于联邦区的 Gama 流域进行了水文建模，该区总面积的 57.5% 被原始的 Cerrado 覆盖。分别在气象站和涡流协方差 (EC) 塔中监测了水文气象和湍流变量。对潜在的蒸散方法进行了 SWAT 模拟：Hargreaves (H)、Priestley-Taylor (PT) 和 Penman-Monteith (PM)。还测试了 Strauch 和 Volk (2013) (SV) 和 Arroio Junior (2016) (AR) 用于估计实际 (ET) 的修改版 SWAT。SWAT 模型在日流量方面的校准和验证使用粒子群优化算法进行，所有评估方法都获得了公平的结果。使用 PM、PT、H、SV 和 AR 方法对 Cerrado 水文响应单元 (HRU) 使用 SWAT (ETsim) 模拟的实际蒸散量 (ET) 进行评估，并与使用湍流（涡流协方差）方法获得的 ET 进行比较(ETobs)。比较 ETobs 和 ETsim 结果，PM 方法显示出最好的适合度，H 和 PT 方法分别显示出更适合旱季和雨季。虽然代表了 ET 建模的进步，