Accelerated disappearance of desert oases: The impact of climate warming and farmland expansion

Abstract

Climate warming and intensified human activities threaten the stability of oasis ecosystems in arid regions, increasing water resource pressure and vegetation degradation. Existing methods fail to fully capture hydrological-vegetation interactions, and research on groundwater depth thresholds remains limited. The Keriya River, which extends deep into the heart of the Taklamakan Desert, serves as a crucial window into the water balance between humans and oases. This study, using multi-temporal Sentinel-2 remote sensing imagery, water resource observation data, and ground survey data from 2016–2024, extracted data on farmland area and watershed area in the middle and lower reaches of the Keriya River over multiple years. An analytical framework integrating remote sensing monitoring, machine learning, and groundwater modeling was constructed to systematically assess the impact of regional farmland expansion on groundwater dynamics and desert riparian forests. Results revealed farmland increased by 31.17 km² year⁻¹. Due to the increase in human water use in the middle reaches, decreasing groundwater levels by 0.04–0.05 m year⁻¹ and straining ecological water supplies. Populus euphratica forest decreased by 4.04 km² year⁻¹, while drought-resistant Tamarix chinensis communities expanded by 3.67 km² year⁻¹, indicating a shift to secondary vegetation. Spatial variations in the fractional vegetation cover indicated a significant decline in vegetation health along the oasis peripheries, with pronounced degradation trends in areas with insufficient surface water supply. Model projections indicate that, if current trends persist, 34.5 % of the total oasis area will have groundwater levels shallower than 6 m by 2120, i.e., below the groundwater level suitable for the growth of desert riparian forests. This would put the oasis ecosystem at risk of large-scale degradation, resulting in long-term and irreversible impacts on protected areas. The methodology improved spatiotemporal resolution, quantitative simulation, and multi-source process integration and provides a novel pathway for investigating hydrological-ecological dynamics in arid regions and scientific evidence for water resource management and ecological conservation. Controlled farmland expansion, improve the legal and regulatory standards system, optimized water usage, and a long-term ecological water supplementation mechanism are recommended to sustain the oasis ecosystem.