Setting up water-saving irrigation strategies is a major challenge farmer’s face, in order to adapt to climate change and to improve water-use efficiency in crop productions. However, there is an increasing need to strategize and plan irrigation systems under varied climatic conditions to support efficient irrigation practices while maintaining and improving the sustainability of ground- water systems. To guide the allocation of water resources in the region, it is beneficial to ascertain the effects of changing the crop planting pattern on water saving and farmland water productivity for irrigation water management. Modelling crop evapotranspiration (ET) response to different planting scenarios irrigation water management in a subtropical climate plays significant role in optimizing crop planting patterns, resolving agricultural water scarcity and facilitating the sustainable use of water resources. We evaluated the changes in water savings in irrigation water management projects and resources, the irrigation water productivity and the net income water productivity under different planting scenarios. Crop production can increase if irrigated areas are expanded or irrigation is intensified, but these may increase the rate of environmental degradation. Since climate change impacts on soil water balance will lead to changes of soil evaporation and plant transpiration, consequently, the crop growth period may shorten in the future impacting on water productivity. Crop yields affected by climate change are projected to be different in various areas, in some areas crop yields will increase, and for other areas it will decrease depending on the latitude of the area and irrigation application. Existing modelling results show that an increase in precipitation will increase crop yield, and what is more, crop yield is more sensitive to the precipitation than temperature. If water availability is reduced in the future, soils of high water holding capacity will be better to reduce the impact of drought while maintaining crop yield. With the temperature increasing and precipitation fluctuations, water availability and crop production are likely to decrease in the future. If the irrigated areas are expanded, the total crop production will increase; however, food and environmental quality may degrade. The results indicate that the efficiency of irrigation has increased by 15~20%, while considering drainage, as compared with conventional irrigation efficiency. Additionally, the adjustment of crop planting scenario can reduce regional evapotranspiration by 14.9%, reduce the regional irrigation volume by 30%, and increase the net income of each regional water area by 16%. The irrigation scenario analysis suggested that deficit irrigation is a “silver bullet” water saving strategy that can save 20–60% of water compared to full irrigation scenarios in the conditions of this review study.

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