阿克苏河流域农田水分利用效率时空格局研究OA

Quantitative assessment of the long-term variations in cropland water use efficiency(WUEc)is crucial for optimizing water resource utilization and achieving high yields as well aseffective water-saving in irrigated ag-riculture in arid regions.This research integrates gross primary productivity of crops(GPPc),grop evapotranspira-tion(ETc),WUEc,and meteorological as well as vegetation data in the Aksu River Basin from 2002 to 2022,a typical arid region,and systematically identifies the spatiotemporal patterns of WUEc and the synergistic effects of multiple driving factorsby applying Sen's slope,the Mann-Kendall trend test,seasonal and trend decomposi-tion using loess,partial correlation analysis,and path analysis.The results indicate the following:(1)Temporal characteristics:GPPc and ETc in the basin increased significantly at rates of 0.6 g C·m-2·a-1 and 0.3 mm·a-1,re-spectively,while WUEc declined at a rate of 0.02 g C·mm-1·m-2·a-1.Intraannual dynamics showed a unimodal pattern for GPPc and ETc(peaking in August),and a bimodal pattern for WUEc(with peaks in April and Octo-ber).(2)Spatial patterns:Regions with declining WUEc accounted for 60.3%of the area under consideration,while those with increasing GPPc and ETc covered 97.1%and 94.8%,respectively,highlighting a widespread phenomenon of"increased production without efficiency gains"in the basin.(3)Driving factor analysis:WUEc was significantly negatively correlated with temperature(T),vapor pressure deficit,and leaf area index(LAI),with the negatively correlated areas corresponding to 77%-89%,and positively correlated with precipitation(Pre),corresponding to 87%of the total area.(4)Path analysis:T and Pre primarily influenced WUEc by regulat-ing GPPc,whereas LAI affected WUEc via ETc.Normalized difference vegetation index and enhanced vegeta-tion index impacted WUEc through the combined regulation of both ETc and GPPc.T and LAI were identified as dominant drivers,suggesting a dual-stress mechanism acting on agroecosystems in arid regions.This study eluci-dates the multi-scale evolution patterns of WUEc in arid regions and its nonlinear driving mechanisms,providing a scientific basis for optimizing agricultural water resource management under climate change.