Climate change constrains suitable cropland area and spatial reconfiguration in a glacier-fed arid oasis

Climate change is intensifying hydrothermal constraints on irrigated agriculture in glacier-fed arid oases, yet its implications for suitable cropland extent and spatial reconfiguration remain insufficiently quantified. We developed an integrated framework combining climate-scenario analysis, degree-day-based glacier runoff simulation, multilayer perceptron projection of total water resources, hydrothermal balance estimation of suitable cropland area (SCA), and ant-colony optimization for cropland spatial allocation to assess future land–water responses in the Weiku Oasis, northwestern China, under SSP1–1.9, SSP2–4.5, and SSP5–8.5. Future hydrothermal conditions were characterized mainly by rising temperature and potential evapotranspiration, whereas precipitation changed little. Glacier runoff and total water resources followed nonlinear increase-then-decrease trajectories; by 2081–2100, they declined by 52.9%–65.5% and 41.0%–45.7%, respectively. Rising crop water demand widened the irrigation supply–demand gap, causing SCA to increase by 8.3%–17.5% in 2021–2040 but decline by 46.7%–47.7% in 2081–2100. Current cropland already exceeds the water-supported carrying capacity by 12.4%. Spatial optimization yielded a pattern of core consolidation with peripheral retirement and increased mean cropland suitability by 12.0%–29.7%. Water-saving scenarios showed that 10%–30% reductions in conventional irrigation demand increased future SCA by 5.2%–23.1%, yet even under WS30, long-term SCA remained 35.0%–36.3% below the historical baseline. These findings identify near-term meltwater enhancement as a temporary window for stage-adaptive adjustment, while long-term adaptation requires coordinated water saving, crop restructuring, and cropland reconfiguration. The proposed framework provides decision support for climate-change adaptation and land–water resource allocation in glacier-fed arid oases.