Comparison of some evapotranspiration models using lysimeter measurements in arid climate conditions

AbstractAccurate calculation of evapotranspiration (ET) for all crops plays an important role. This study was conducted to determine the most accurate reference evapotranspiration (ETr) estimation model for arid climatic conditions using the decision support system (DSS) program for alfalfa plants in south‐east Anatolia, Turkey, in 2019 and 2020. The evapotranspiration of 12 mathematical models (ETr‐m) and the evapotranspiration of a lysimeter (ETr‐l) were used to estimate ETr. In 2 experimental years, 1133 and 1270 mm of irrigation water were applied to alfalfa plants, respectively. The actual total ET was calculated as 1288 and 1294 mm in 2019 and 2020, respectively. The root mean square error (RMSE), mean absolute error (MAE), ETr‐m/ETr‐l, and index of agreement (d) were calculated separately for each mathematical model. The RMSE, MAE, ETr‐m/ETr‐l and d values for the mathematical models had a range of 1.25–3.57 mm day−1, 0.91–1.98 mm day−1, 0.64–1.04 and 0.56–0.94, respectively. According to the results of the regression analysis with the RMSE, MAE, ETr/ETr‐m and d values obtained from the models, the Businger–Van Bavel model was the most accurate prediction model. The others were the FAO PPP‐17 Penman and the 1982 Kimberly Penman models, respectively.