| Summary: | Rubber (<i>Hevea brasiliensis</i>) plantations have high water consumption through evapotranspiration, which can contribute to water scarcity. In addition, there is a lack of spatial observation data and estimation methods for evapotranspiration (<i>ET</i>) for rubber plantations. To alleviate the water stress of expanding rubber plantations caused by seasonal drought in Xishuangbanna, Southwest China, an up to 7 days crop evapotranspiration (<i>ET<sub>c</sub></i>) forecast method, “<i>K<sub>c</sub></i>-<i>ET</i><sub>0</sub>” for rubber plantations with limited meteorological data, was proposed by using rubber crop coefficient <i>K<sub>c</sub></i> and public weather forecasts. The results showed that the average absolute error (MAE) of forecasted <i>ET<sub>c</sub></i> was 0.68 mm d<sup>−1</sup>, the root mean square error (RMSE) was 0.85 mm d<sup>−1</sup>, and the average correlation coefficient (R) was 0.69 during the rainy season, while during the dry season these metrics were 0.52 mm d<sup>−1</sup>, 0.68 mm d<sup>−1</sup>, and 0.85, respectively. The accuracy of <i>ET<sub>c</sub></i> forecast in the dry season was higher. Additionally, <i>K<sub>c</sub></i> was the main factor influencing the accuracy of rubber plantations <i>ET<sub>c</sub></i> forecast, while the accuracy of the temperature forecast and the chosen Hargreaves-Samani (HS) model were also considerable. Our results suggested that the “<i>K<sub>c</sub></i>-<i>ET</i><sub>0</sub>” short-term rubber plantation <i>ET<sub>c</sub></i> forecasting method shows good performance and acceptable accuracy, especially in the dry season. The study provides an important basis for creating ET-based irrigation scheduling for improving regional-scale water management in high water consumption rubber plantations.
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