ETmax ETact BF Ef Rain

Figure 11: Water balance components in a sugarbeet irrigated plot at current and 2025 climate conditions.

The water balance analysis comprises the Priestley and Taylor maximum evapotranspiration, as well as the simulated sugarbeet actual evapotranspiration, the simulated bottom flux under the 1-m soil layer considered for simulations and the effective rain.

As can be seen in the figure, the considered irrigation management is able to cover the sugarbeet irrigation management at current conditions, since the crop actual evapotranspiration is almost equal to the maximum evapotranspiration. The irrigation watermanagement was correct from the crop water-use point of view, since soil water contents were over or close to field capacity as can be seen in Figure 8. However, water use efficiency is low, since the simulated bottom flux is very large. The considered irrigation management could still be improved, changing the irrigation frequency and the water depth in order to minimize water looses keeping soil water contents close to filed capacity. Playan and Mateos

(2005) pointed out also that despite irrigation managements in Spain are generally able to fulfil crop water requirements; water use efficiency can still be largely improved.

The maximum evapotranspiration in 2025 is higher and the effective rain is lower than in current conditions, which agrees with the Climate Change assessments. However, the considered irrigation management is still able to fulfil the sugarbeet water requirements, in average. Accordingly, the water use efficiency is higher since the water looses by percolation are lower.

Besides the average results shown in Figure 11, Figure 12 depicts the simulated actual sugarbeet evapotranspiration under the irrigation period for the current and the 2025 climate conditions.

Figure 12: Sugarbeet actual evapotranspiration (ETc) during the crop irrigation period at current and 2025 climate conditions. Vertical bars indicate ETc variability.

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