Long-term irrigation as a double-edged sword: staged ecological stabilization and salinization-risk amplification in...

Long-term irrigation may overcome ecological barrenness caused by water shortage in arid desert regions, yet process-based evidence remains limited as to how irrigation-driven vegetation recovery, groundwater salinization, soil salt accumulation, and ecological risk interact across different stages of long-term irrigation, and whether its ecological effects shift over time from a stabilizing force to a risk amplifier. Taking the Jingdian Irrigation District, a large power lift-irrigated artificial oasis developed in Northwest China since the 1970s, as a pilot area, and using the cloud model, risk-change mapping, geographical detector, and structural equation modeling as analytical solutions, this study integrated remote sensing, ground monitoring, and spatial data from 1985, 2000, 2010, and 2022 to systematically identify the staged evolution of salinization risk, ecological risk, and their driving pathways under long-term irrigation. The results show that long-term irrigation induced a pronounced asynchronous evolution between salinization risk and ecological risk. Salinization risk increased rapidly, with the proportion of severe and extremely severe salinization-risk areas rising from 10.94% in 1985 to 55.09% in 2010 and still accounting for 46.45% in 2022, and ecological risk, by contrast, decreased markedly, with severe and extremely severe ecological-risk areas declining from 28.95% in 1985 to 5.36% in 2022, although a slight rebound occurred during 2000-2010. Furthermore, ecological risk decreased mainly in the early stage of irrigation-area development, with the early-stage change type accounting for 57.62% of the study area, but water-salt-stressed salinization remained prominent in the later stage of irrigation-area development. The driving mechanisms was supposed that the dominant pathway of ecological risk shifted from an early pattern in which water resources promoted vegetation restoration and reduced ecological risk to a later pattern in which water resources induced water-salt stress and amplified potential risk. These findings indicate that long-term irrigation in arid regions can drive surface oasis expansion but also subsurface salinization, revealing a stage-dependent double-edged process that first acts as a stabilizing force and later becomes a potential risk amplifier. Therefore, irrigation management in arid regions should shift from water-supply expansion toward water-salt threshold regulation to maintain ecological stability and prevent hidden salinization risks.