Study region The Manas River Basin in Northwest China represents a typical arid endorheic basin characterized by a distinct mountain-Gobi-oasis-desert continuum. However, the regulatory mechanisms of ETa spatial differentiation across this complex hydrogeological gradient have rarely been systematically analyzed. Research focus In this study, we employed a hydrogeological gradient perspective, integrating multi-source data (2000-2023) with Shapley Additive Explanations (SHAP) to disentangle the natural and anthropogenic controls on ETa along the mountain-Gobi-oasis-desert continuum. New hydrological insights ETa controls systematically shift along the hydrogeological gradient, with annual ETa peaking in the oasis (132-192 mm) and minimizing in the desert (16-60 mm). Alpine headwaters operate under an energy-limited regime, while the Gobi and desert zones are restricted by wind-driven advection and severe moisture deficits. Within the oasis zone, ETa is strictly governed by a similar to 4 m water table depth threshold for natural ecosystems, beyond which fluxes precipitously decline by 30%-50%. Conversely, intensive irrigation supplants this natural constraint by maintaining soil moisture within an optimal range of 14%-16%, leading to a decoupling of crop ETa from local groundwater dynamics. This anthropogenic decoupling sustains high transpiration but incurs a severe hydrological deficit, driving progressive aquifer depletion. Synthesizing these findings, we propose a spatially partitioned conceptual model of ETa regulatory regimes that replaces generic multi-factor frameworks, thereby providing a precise physical basis for sustainable water management in arid regions.