Rhine

In contrast to other basins and crops, sugarbeet yield is not highest in the period 2070-2099, but peaks in 2010-2039. The main reason is the projected lower precipitation, but especially the shift in precipitation patterns. Annual average precipitation will be reduced by less than 10% in 2070-2099, but rainfall in the sugarbeet growing season will reduce by 412, 386 and 231 mm/year for the periods 1961-1990, 2010-2039 and 2070-2099, respectively. At the same time, crop water requirements are higher due to increased temperatures.

In case of low groundwater tables, these effects are even more profound and sugarbeet yields will be lower as capillary rise, an important water source during dry periods, will be reduced. Also interesting is the enormous increase in expected yield variation for the 2010-2039 and 2070-2099 periods. A possible option to reduce these negative impacts of climate change might be to reduce the length of the growing period, providing suitable varieties exist. Although less water will be consumed and water productivity is similar, crop yields are lower and this option is not really solving the problem. In addition, prices for sugarbeet are related to sugar content of the beets, which is normally negatively affected by shorter seasons.

The wheat crop shows a pattern similar to sugarbeet, although the increase in yield for the period 2010-2039 is less profound (Fig. 3.7). The crop is also less sensitive to lower groundwater levels. Changing the growing season would not increase crop yields or water productivity (Fig. 3.11).

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