Waterbeschikbaarheid (kwantiteit en kwaliteit) (KB-24-003-020)

Water scarcity is likely to increase due to climate change, and farmers have different adaption measures to consider. Therefore, it is important to assess the impact of water scarcity on agriculture and the effect of potentially efficient adaptation measures and adverse effects. Various approaches are developed to estimate these effects, all with their advantages and disadvantages, e.g. hydrological models, and computable general equilibrium (CGE) models. Generally, if adaptation is excluded, water use is likely to be overestimated and food production underestimated. Accurate estimations of food production and agricultural water use is important to target the Sustainable Development Goals on the “Zero hunger” (SDG2) and the ”Clean water and sanitation” (SDG6) objectives. CGE models applied at the national, river basin or global level include water and the trade-off between agriculture and other sectors; adaptation however is included exogenously. The behaviour of farmers for adapting to water scarcity was poorly incorporated in the models considered. This paper proposes a methodology to improve on the accuracy of impacts of agricultural water use and food production. We elaborate on the use of CGE models for determining the impact of water scarcity, as we analyse the agricultural impact of less water availability and micro adaptation measures. Different ways to incorporate these features in CGE models were evaluated. More elaborate production structures in the CGE models improve the incorporation of farmers’ adaptation with focus on substitution of inputs (and outputs). We provided challenges to improve CGE models to better estimate the impact of increasing water scarcity while taking into account adaptation at farm level. This approach better links the results of plot-level adaptation measures to CGE models and provide more accurate estimates of the impacts or future water availability and food production.