Land suitability and sustainable expansion potential for irrigation in Northwest China drylands under climate change

Climate change is widely recognized as a significant challenge to sustainable food production, particularly in drylands where water resources are limited and agriculture heavily relies on irrigation. Exploring potential pathways for irrigation expansion is crucial for balancing food security and ecosystem stability in drylands under a warming climate. In this study, we focused on a climate-sensitive hotspot in the arid regions of North west China, where irrigated agriculture has expanded rapidly under a warming climate and increasing water demand. A GIS-based Multi-Criteria Evaluation (MCE) framework was applied to assess land suitability for irrigation across a baseline period (from 2004 to 2023) and projected future periods (from 2041 to 2060 and from 2081 to 2100) by integrating biophysical and socio-economic factors. For future periods, this study focused on climate-driven changes in potential land suitability for irrigation through projected precipitation and potential evapotranspiration, while other conditions were held constant. In addition, the discrepancy between land suitability for irrigation areas and existing irrigated areas was examined. The results indicated that during the baseline period (2004–2023), approximately 8166.12 kha (5.01%) of the area was identified as highly suitable for irrigation, primarily concentrated in the oasis regions of the Tianshan Mountains. Meanwhile, only about 8.37% of existing irrigated land was located in highly suitable for irrigation land, which was predominantly occupied by grassland rather than cropland. However, this spatial mismatch does not imply that the current distribution of irrigation is inefficient, as the actual development of irrigation is also shaped by historical reclamation, irrigation infrastructure, water allocation policies and socio-economic factors. Future projections indicated that under the SSP245 scenario by the end of the 21st century, increased precipitation will partially offset the rise in potential evapotranspiration, resulting in a slight increase of highly suitable for irrigation land compared with the baseline level. However, under other climate scenarios, the area of highly suitable for irrigation land will generally decrease. Therefore, to ensure water security and sustainable agricultural development in arid regions, the adoption of water-saving irrigation technologies and improvements in crop productivity will be essential.