Ecozone-dependent reorganization of multifactor interactions controls actual evapotranspiration across arid mountain-basin systemsOA

Actual evapotranspiration(ETa)is a key regulator of land-atmosphere water and energy exchanges in arid regions.However,the coupled effects of its controlling factors along mountain-basin gradients remain poorly quantified,limiting precise water resource management.Based on multi-source data(2001-2022)from Xinjiang Uygur Autonomous Region,China,this study analyzed the spatiotemporal patterns of ETa across five eco-zones:the Altay Mountains,Junggar Basin,Tianshan Mountains,Tarim Basin,and Kunlun Mountains.Using Mann-Kendall and Theil-Sen trend analyses,GeoDetector,and Random Forest model,we quantified the contributions and interactions of seven environmental drivers:air temperature,precipitation,soil moisture,wind speed,net radiation,vapour pressure deficit,and leaf area index.The multi-year mean ETa over Xinjiang was 193.15(±21.16)mm/a,showing a distinct"high in mountains and low in basins"spatial pattern.A significant increasing trend of 1.60 mm/a was observed regionally,yet with clear spatial divergence,i.e.,ETa increased in the major mountain ranges but decreases or stabilized in the hyper-arid Tarim Basin and transitional Junggar Basin.Water-supply factors(precipitation and soil moisture)explained about 40%of the spatial variance individually,while factor interactions enhanced the explanatory power substantially(maximum interaction gain(Δ_(q))=0.18),indicating that bivariate and nonlinear combinations captured ETa patterns more effectively than single driver.Interaction regimes were strongly ecozone-dependent and varied between wet and dry years.Through comparing the wet year(2003)with the dry year(2022),we found a reorganization of dominant interaction pairs:the hyper-arid Tarim Basin shifted from hydrothermal control to vegetation-water-stress coupling;the Junggar Basin maintained persistent vegetation-energy coupling;the Altay and Tianshan Mountains strengthened vegetation-mediated interactions during drought;and the Kunlun Mountains transition from hydrothermal to moisture-aerodynamic control.These results clarify how complex topography and vegetation physiology modulate macroclimatic forcing in this arid mountain-basin system.These findings offer a process-based foundation for ecohydrological zoning,and provide critical insights for adaptive water ecosystem management and sustainable development in response to the"warming and wetting"trend in global drylands.