Irrigation & Drainage Systems Engineering

Comparison of Measured and Estimated Sugarcane Water Requirement under Arid and Semi-Arid Climatic Condition: The Case of Wonji Shoa Sugarcane Plantation, Ethiopia

Abstract

Belay Yadeta*, Mekonen Ayana, Muluneh Yitayew and Tilahun Hordofa

Sugarcane is one of the most important commercial crops cultivated mostly on the large scale basis all over the world from arid to semi-arid climate condition like Ethiopia. Wonji shoa sugarcane plantation was the first large scale irrigation in Ethiopia. But sugarcane crop is the most water intensive crop that requires critical determination of its evapotranspiration. Determination of crop evapotranspiration is more accurate through experiment but experiment was not mostly undertaken due to high cost, lack of instruments and laboratory facilities, and time it required. But to overcome those problems, some models were developed as an option in determining the crop evapotranspiration. In line with this, the current study focused on the performance evaluation of sugarcane evapotranspiration determined by different models as compared to the lysimeter experiment under study area. The main objective of this study was to analysis the variation of sugarcane evapotranspiration measured from the lysimeter experiment and that determined using different models under the current study climatic condition. In the current study, Blaney-Criddle, Drooger and Allen, Hargreaves, Irmak, Tabari and Thornthwaite were selected. The selected models were required only few climatic parameters. After reference evapotranspiration was determined by each selected models, the sugarcane evapotranspiration was determined by multiplying those reference evapotranspiration by crop coefficient recommended by FAO-56. The performances of those models were evaluated using the most commonly used statistical indices. Those statistical indices used were RMSE, MBE, t-test, R² and IA. After all the data computed by each selected models the analysed, Blaney-Criddle model was the best model in determining the sugarcane evapotranspiration as compared to the lysimeter experiment followed by Irmak models. Therefore, from the current findings, it can be concluded that Blaney- Criddle model can be used to determine sugarcane evapotranspiration under current study climatic condition.