Study region: Northern China's agro-pastoral ecotone (APE), a semi-arid to semi-humid transitional zone encompassing five major watersheds: Songhua River Basin (SHB), Liaohe River Basin (LB), Haihe River Basin (HB), Yellow River Basin (YB), and Inner Mongolia Endorheic Basin (EB). Study focus: We integrated high-resolution surface water datasets with hydro-meteorological products and land use records to assess impacts on net water yield (NWY). Analysis of surface water dynamics (areas > 1 ha) was conducted using Theil-Sen slope estimation and structural equation modeling. New hydrological insights: The APE experienced marginally significant hydrological aridification during 1986-2020, characterized by net surface water loss (-4140 ha yr(-1), p = 0.052) and declining water body numbers (-158.7 yr(-1), p = 0.092). Watershed trends exhibited pronounced divergence, with the most severe depletion in the LB (-1523 ha yr(-1) and -55.7 water bodies yr(-1)) and moderate declines in the EB (-716 ha yr(-1) and -7.2 yr(-1)), contrasting sharply with significant expansion in the YB (1169 ha yr(-1) and 46.2 yr(-1), p < 0.001). Major lakes/reservoirs underwent a significant shrinkage, with relative water area (RWA) declining at -1.22 % yr(-1) (p < 0.05) and the maximum shrinkage rate in the LB (-3.29 % yr(-1), p < 0.001). A declining aridity index and intensified land use, particularly irrigation expansion and revegetation, amplified evapotranspiration (ET), with cropland areas since 2000 showing average ET increases of 1.9 +/- 2.6 mm yr(-1) (GLEAM) and 6.5 +/- 2.5 mm yr(-1) (MODIS), thereby diminishing NWY across the APE. These divergent watershed trajectories demonstrate that anthropogenic interventions have outweighed climatic drivers to reconfigure surface water distribution. This human-mediated redistribution of water resources necessitates watershed-specific allocation frameworks to secure regional water sustainability.