Exploring the impact of seasonal water variability on agricultural planning: a water-energy-food nexus perspective

Abstract Increased global warming is projected to alter rainfall patterns, intensifying pressure on water availability. The already acknowledged 2.3 – 2.5◦C temperature increase under current policies calls for progress in adaptation planning. We developed a Climate, Land, Energy, and Water systems (CLEWs) model with explicit seasonal crop growing stages and seasonal hydrological cycles. We applied the method to the case study of Ethiopia and used it to explore the impact of seasonal water variability on agricultural planning and investigate the impact of agricultural adaptation on water stress. We compared standardised IPCC scenarios with historical trends and observed that seasonal differences in precipitation increase by 9.5% and 20% on a national scale for medium (RCP4.5) and high (RCP8.5) impact climate trajectories. We found that integrated resource models that do not account for seasonal hydrological variability overestimate available renewable water by 50% for groundwater recharge and 105% for surface water during dry seasons. We also found that representing seasonal crop water requirements for irrigation has a direct impact on the unit cost of water. The presence of seasonal variability can catalyse the adoption of mechanisation and irrigation in least-cost solutions, leading to an increase of up to 42% in irrigated area and reducing electricity demand by up to 5% during the dry season, when less water is required. This study enhances the representation of the water sub-system in an integrated resource model, enabling a more detailed assessment of the implications of climate change and irrigation scenarios on agricultural planning.