Evaluation of Different Crop Models for Estimating the Potentials to Increase the Water Use Efficiency under Climate Variability Évaluation Des Modeles De Cultures Differentes Pour Estimer Le Potentiel D'augmenter L'efficacite D'utilisation De L'eau En Vertu De La Variabilite Du Climat

The interest in techniques to improve water use efficiency (WUE) such as controlled deficit irrigation is rising due to the emergence of strong competition for fresh water in order to comply with the increased demand for food worldwide. Additionally, the use of crop models in conjunction with complex decision support systems becomes more and more widespread making it essential to reliably predict WUE as ratio of water consumption and yield. The objective of this paper is the assessment of the problems that occur when certain crop models are applied to maximize the WUE. The crop models FAO-33, DAISY, and APSIM were used to calculate the risk in yield reduction in view of different sources of uncertainty, such as climate, while a stochastic framework for decision support for the planning of water supply in irrigation was employed. The stochastic framework consists of: (i) a weather generator for simulating regional impacts of climate change; (ii) a new tailor-made evolutionary optimization algorithm for optimal irrigation scheduling with limited water supply; and (iii) the above mentioned models for simulating water transport and crop growth in a sound manner. The results present stochastic crop water production functions (SCWPF) for different crops which can be used as basic tool to assess the impact of climate variability on the risk for the potential yield. Case studies from India, Oman, Malawi, and France are provided to evaluate the differences in modeling water stress and yield response for the different crop models.